METHOD OF MAKING LARGE SPRING INDEX ARTIFICIAL MUSCLES

Abstract

Methods for fabricating coiled polymer fibers and yarns (high-spring-index coiled fibers and yarns). Methods include inserting twist separately into individual fibers or yarns, plying the fibers or yarns by inserting plying twist, setting the ply structure without permanently binding together the fibers or yarns of different plies so that the ply structure is substantially stable against untwist when torsionally untethered, and then unwrapping the plied fibers or yarns so that a high-spring-index fiber or yarn can be obtained. In some embodiments, the unwrapped fibers or yarns are further set so that these are further stabilized. The methods can eliminate the need for a mandrel, and can be quickly applied for applications where high-spring-index thermally-driven artificial muscles are presently employed, such as for presently commercialized comfort-adjusting jackets.

Description

FIELD OF THE INVENTION

The mandrel-free fabrication of high-spring-index yarns and fibers.

BACKGROUND OF INVENTION

Very large spring index coiled artificial muscles are needed for many applications, because a large spring index increases muscle stroke. The coiled muscles can optionally be made from either a single fiber or a yarn that potentially comprises many fibers. Hence, when the term “yarn” or “fiber” is referenced, this reference can be applied to either yarns or fibers, unless otherwise indicated. The known method for making these large spring index coiled polymer muscles is by coiling twisted fibers around a large cylindrical or quasi-cylindrical mandrel, since increasing the mandrel's diameter to substantially above the yarn's diameter increases the spring index of the muscle. However, this method of coiling around a mandrel is expensive to realize and can introduce imperfections. This is because it involves either obtaining a high-spring-index product fiber by rotating a precursor fiber around a stationary cylindrical mandrel or rotating the mandrel as the input fiber is translated along the mandrel's length. Thereafter, a large spring index mandrel-free fiber can be obtained by removing the coiled fiber from the mandrel. However, there are important problems. First, the need to remove the coiled fiber from the mandrel by withdrawing the mandrel limits the length of mandrel and correspondingly limits the length of the coiled fiber that can be produced. Second, the described use of a rotating mandrel and a translating fiber input can introduce defects in the coiled yarn because of imprecise control of mandrel rotation versus input fiber translation.

It is known in the prior-art that high-spring-index yarns or fibers can be thermally set by thermal annealing the mandrel-coiled yarn while it is on the mandrel. This mandrel-wrapped yarn or fiber can then be completely freed from the mandrel by using a liquid to dissolve the mandrel [Ridley '979 patent] or exposing the mandrel-wrapped yarn or fiber to thermal or chemical reaction conditions that eliminates the mandrel without adversely affecting the initially surrounding polymer fiber or yarn. However, such processes for eliminating the mandrel are wasteful, since they waste the material used for the mandrel and unnecessarily create a corresponding waste stream. Thus, improved large spring index artificial muscles and methods of making same are needed.

SUMMARY OF INVENTION

In general, in one embodiment, the invention features a method for making a high-spring-index coiled fiber or yarn without using a sacrificial core material whose diameter approximately defines the inner-coil diameter. The method includes inserting twist separately into two or more individual fibers and/or yarns. The method further includes plying the two or more individual fibers and/or yarns by inserting plying twist to form a multi-ply structure. The method further includes setting the multi-ply structure without permanently binding together the two or more individual fibers and/or yarns of different plies in the multi-ply structure so that the multi-ply structure is substantially stable against untwist when torsionally untethered. The method further includes, after the step of setting, unwrapping the two or more individual fibers and/or yarns of different plies in the multi-ply structure to obtain the high-spring-index fiber or yarn.

Implementations of the invention can include one or more of the following features:

The step of setting can include a process selected from the group consisting of thermal annealing, exposure to actinic radiation, exposure of the two or more individual fibers and/or yarns to an absorbed liquid, infiltration of a binding agent into the two or more individual fibers and/or yarns, and combinations thereof.

The step of setting can include a thermal annealing process.

The two or more individual fibers and/or yarns can include a carbon nanotube yarn. The step of setting can include thermal setting comprising an incandescent tensile annealing process.

The two or more individual fibers and/or yarns can include an individual fiber and an individual yarn. At least one of the individual fiber and the individual yarn can be selected from the group consisting of elastomeric polymers, non-elastomeric polymers, metal wires, metal yarns, carbon fibers, carbon yarns, carbon nanotube yarns, and combinations thereof.

The two or more individual fibers and/or yarns can include at least one individual fiber or yarn that has different characteristic to at least one other individual fiber or yarn. The different characteristic can be selected from the group consisting of a different diameter, a different amount of twist, an opposite chirality of twist, and combinations thereof.

All of the two or more individual fibers and/or yarns can have a same diameter, a same amount of twist, and a same chirality of twist to each of the other two or more individual fibers.

The two or more individual fibers and/or yarns can include a metal wire or yarn.

The metal wire can be a shape-memory metal wire or yarn.

The step of unwrapping the two or more individual fibers and/or yarns can obtain two or more high-spring-index fibers and/or yarns. The two or more individual fibers and/or yarns used in the method can become the two or more high-spring-index fibers and/or yarns extracted from the multi-ply structure.

The two or more individual fibers and/or yarns can include at least one polymer fiber or polymer yarn. The at least one polymer fiber or polymer yarn can include a polymer. The step of setting can include subjecting the at least one polymer fiber or yarn to a first thermal annealing process. The thermal annealing process can be conducted at a temperature above glass transition temperature of the polymer and below melting point of the polymer. The thermal annealing process can be conducted while the multi-plied structure is tethered.

The method can further include, after the step of unwrapping, performing a second thermal annealing process in which the high-spring-index coiled fiber is thermally annealed when not torsionally or positionally tethered.

The second thermal annealing process can be performed at a temperature that is above the glass transition temperature of the polymer, below the melting point of the polymer, and above the temperature of the first thermally annealing process.

Each of the two or more individual fibers and/or yarns can include polymers. Each of two or more individual fibers and/or yarns can be unwrapped from the multi-ply structure as high-spring-index fibers and/or yarns.

The two or more individual fibers and/or yarns can include three or more individual fibers and/or yarns. The step of unwrapping can include that at least two, but not all, of the three or more individual fibers and/or yarns are unwrapped from the multi-ply structure without unwrapping them from one another to obtain the high-spring-index fiber or yarn.

The setting of the multi-ply structure can be region specific, such that different regions of the multi-ply structure are differently set.

The setting can include a region-selected thermal treatment process.

The high-spring-index fiber and/or yarn can have a spring index of at least 2.

The spring index can be at least 2.5.

In general, in another embodiment, the invention features a method that includes selecting a plurality of high-spring-index coiled fibers and/or yarns. Each high-spring-index coiled fiber and/or yarn in the plurality is made by one of the above-described methods. The method further includes fabricating a two-layer textile by incorporating the plurality of high-spring-index coiled fibers and/or yarns into the two-layer textile. The two-layer textile changes insulation when ambient temperature changes.

Implementations of the invention can include one or more of the following features:

The two-layer textile can have a first layer and a second layer. The first layer can have a first-layer inner face and a first-layer outer face. The second layer can have a second-layer inner face and a second-layer outer face. The first-layer inner face and the second-layer inner face can be facing toward one another. The first-layer outer face and the second-layer outer face can be facing away from one another. The incorporating of the plurality of high-spring-index coiled fibers and/or yarns into the two-layer textile can include a tailoring process selected from the group consisting of sewing, stitching, embroidering, weaving, and combinations thereof. A first portion of the high-spring-index coiled fibers and/or yarns can be on or outside the first-layer outer face and a second portion of the high-spring-index coiled fibers and/or yarns can be on or outside the second-layer outer face, such that the high-spring-index coiled fibers and/or yarns can be incorporated as artificial muscles on or outside the first layer and the second layer. The artificial muscles can be either (i) homochiral to increase the insulation of the two-layer textile when the ambient temperature gets colder than a desired temperature or (ii) heterochiral to increase the insulation of the two-layer textile when the ambient temperature gets warmer than the desired temperature.

The two-layer textile can have a first layer and a second layer. The first layer can have a first-layer inner face and a first-layer outer face. The second layer can have a second-layer inner face and a second-layer outer face. The first-layer inner face and the second-layer inner face can be facing toward one another. The first-layer outer face and the second-layer outer face can be facing away from one another. A first portion of the high-spring-index coiled fibers and/or yarns can be on or inside the first-layer inner face and a second portion of the high-spring-index coiled fibers and/or yarns can be on or inside the second-layer inner face, such that the high-spring-index coiled fibers and/or yarns can be incorporated as artificial muscles on or between the first layer and the second layer. The artificial muscles can be either (i) homochiral to increase the insulation of the two-layer textile when the ambient temperature gets warmer than a desired temperature or (ii) heterochiral to increase the insulation when the ambient temperature gets colder than the desired temperature.

In general, in another embodiment, the invention features a method including selecting a first plurality of first two-layer textiles and a second plurality of second two-layer textiles. Each first two-layer textile in the first plurality of two-layer textiles is made by a first method of the above-described methods. Each second two-layer textile in the second plurality of two-layer textiles is made by a second method of the above-described methods. The method further includes fabricating an assembly by incorporating the first plurality of two-layer textiles and the second plurality of two-layer textiles into the assembly. One of the first plurality of two-layer textiles of the assembly and the second plurality of two-layer textiles of the assembly increases insulation of the assembly when ambient temperature gets colder than a desired lower temperature. The other of the first plurality of two-layer textiles of the assembly and second plurality of two-layer textiles of the assembly increases insulation of the assembly when ambient temperature gets warmer than a desired upper temperature.

Implementations of the invention can include one or more of the following features:

The first plurality of two-layer textiles of the assembly can increase insulation of the assembly when ambient temperature gets colder than a desired lower temperature. The second portion of plurality of two-layer textiles of the assembly can increase insulation of the assembly when ambient temperature gets warmer than a desired upper temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a 2-ply polymer yarn immediately before the onset of plied yarn coiling. The scale bar shown here is 1 mm long.

FIG. 2 shows a 2-ply polymer yarn immediately before the onset of plied yarn buckling.

FIGS. 3A-3C show fabrication of a high-spring-index polymer fiber from a 3-ply polymer yarn. FIG. 3A shows the 3-ply polymer yarn immediately before the onset of plied yarn buckling or snarling. FIG. 3B shows an individual polymer fiber from the 3-ply polymer yarn shown in FIG. 3A after stabilizing by a first thermal annealing and unplying. FIG. 3C shows the unplied individual polymer fiber of FIG. 3B after a second thermal annealing (the high-spring-index polymer fiber).

FIG. 4 shows the performance of the high-spring-index polymer fiber shown in FIG. 3C as a thermally driven artificial muscle. FIG. 4 shows the dependence of the contractile stroke and gravimetric work capacity on the tensile stress for the high-spring-index polymer fiber.

FIGS. 5A-5D show fabrication of a high-spring-index polymer fiber from a 4-ply polymer yarn. FIG. 5A shows the 4-ply polymer yarn immediately before the onset of plied yarn buckling or snarling. FIG. 5B shows the 4-ply polymer yarn after stabilizing by a first thermal annealing with partial unplying. FIG. 5C shows a magnified view of an individual polymer fiber from the 4-ply polymer yarn shown in FIG. 5B. FIG. 5D shows the unplied individual polymer fiber of FIG. 5C after a second thermal annealing (the high-spring-index polymer fiber).

FIGS. 6A-6B show the performance of the high-spring-index polymer fiber shown in FIG. 5D as a thermally-driven artificial muscle. FIG. 6A shows the muscle length change of the high-spring-index polymer fiber. FIG. 6B shows that the high-spring-index polymer fiber provides a contractile stroke when the temperature is increased and an elongational stroke when the temperature is decreased.

FIG. 7 shows the performance of the high-spring-index polymer fiber shown in FIG. 5D as a thermally driven artificial muscle. FIG. 7 shows the dependence of the contractile stroke and gravimetric work capacity on the actuation temperature for an applied tensile load of 1.13 MPa for the high-spring-index polymer fiber.

FIGS. 8A-8B shows the actuation performance of ply-extracted high-spring-index polymer fibers when the temperature was increased from room temperature to 105° C. FIG. 8A shows the dependence of the contractile stroke on the tensile stress for the high-spring-index polymer fibers derived using different stresses during plying. FIG. 8B shows the dependence of the work capacity on the tensile stress for the high-spring-index polymer fibers derived using different stresses during plying.

FIG. 9 shows actuation cycles for ply-extracted high-spring-index polymer fibers made using different applied fiber twist load during twist insertion when the temperature was increased from room temperature to 105° C. to provide a contraction and decreased from room temperature to −15° C. to provide an elongation.

FIGS. 10A-10B shows the actuation performance of ply-extracted high-spring-index polymer fibers made from a 4-ply yarn in which different stresses were applied during twist insertion but the same stress was applied during plying. The temperature was increased from room temperature to 105° C. to provide a contraction. FIG. 10A shows the dependence of the contractile stroke on the tensile stress for the high-spring-index polymer fibers. FIG. 10B shows the dependence of the work capacity on the tensile stress for the high-spring-index polymer fibers.

FIGS. 11A-11B shows actuation for ply-extracted high-spring-index polymer fibers at different twist densities of the initial twist. FIG. 11A shows the magnitude of the contractile stroke and elongational stroke for different twist densities of the initial twist. FIG. 11B shows the dependence of the contractile stroke and elongational stroke when the twist density of the initial twist was increased.

FIG. 12 shows actuation cycles for ply-extracted high-spring-index polymer fibers annealed at different second annealing temperatures.

FIG. 13 shows actuation temperature dependence of the non-loaded contractile stroke of ply-extracted high-spring-index polymer fibers during actuation for fibers exposed to a second thermal setting temperature of either 115 or 150° C.

FIGS. 14A-14B show the tensile stress dependence of the contractile stroke and contractile work capacity, respectively, of ply-extracted high-spring-index polymer fibers during actuation for different second annealing temperatures or different driven temperatures.

FIGS. 15A-15C show fabrication of a high-spring-index CNT yarn from a 3-ply CNT yarn.

FIG. 15A shows incandescent tension anneal process (ITAP) treated 3-ply CNT yarn immediately before the onset of plied yarn coiling. FIG. 15B shows the ITAP-treated, 3-ply CNT yarn of FIG. 15A after anneal with a slight untwist (beginning of unplying). FIG. 15C shows the three unplied individual CNT yarn of FIG. 15B after being unplied (the extracted high-spring-index coiled CNT yarn).

FIG. 16 shows the dependence of the contractile stroke and gravimetric work capacity on the tensile stress for adsorption-driven actuation performance of the ply-extracted high-spring-index CNT yarn shown in FIG. 15C when methanol was adsorbed and desorbed from the yarn during its use as a methanol-adsorption-powered muscle.

FIGS. 17A-17B show the performance of the high-spring-index CNT yarn shown in FIG. 15C as an electrochemical-driven artificial muscle in an electrolyte. FIG. 17A shows the stress-free contractile stroke of the ply-extracted CNT yarn muscle for increasing applied inter-electrode voltage. FIG. 17B shows the dependence of the contractile stroke and gravimetric work capacity on the tensile stress.

FIGS. 18A-18B show fabrication of a high-spring-index polymer fiber from a 2-ply polyurethane yarn. FIG. 18A shows the 2-ply polyurethane yarn after thermal anneal when partially unplied. FIG. 18B shows one of the individual coiled fibers after thermal anneal and extraction.

FIG. 19 shows the dependence of the contractile stroke and gravimetric work capacity on the tensile stress for the high-spring-index polymer fiber shown in FIG. 18B as a thermally driven artificial muscle.

FIG. 20 shows the effect of a second high-temperature thermal annealing time on the performance of the polymer fiber shown in FIG. 18B. FIG. 20 shows the dependence of the tensile stroke and gravimetric work capacity on the tensile stress.

FIGS. 21A-21D show the dependence of actuation on the length of the second high-temperature thermal annealing time. FIGS. 21A-21B show tensile stroke and work capacity, respectively, by applying a second anneal for durations of 0, 0.5, 1, 2, 3.4, and 5 hours to ply-extracted fibers. FIG. 21C shows the change in length by applying the second anneal for durations of 0, 0.5, 1, 2, 3.4, and 5 hours to the ply-extracted fibers. FIG. 21D shows a comparison of the work capacity of the ply-extracted fibers after the second anneal to the ply-extracted fibers before the second anneal.

FIG. 22 shows the dependencies of spring index, coil bias angle, and length per coil of two-ply ply-extracted coiled nylon fibers on the temperature during the second thermal annealing.

FIG. 23 shows the magnitudes of actuation stroke (contraction and elongation) for ply-extracted high-spring-index polymer fibers for different second anneal temperatures.

FIG. 24 shows the temperature dependence of the second-anneal-temperature-optimized contractile stroke for a high-spring-index polymer fiber.

FIG. 25 shows the performance of a high-spring-index polymer fiber as a thermally driven artificial muscle. FIG. 25 shows the dependence of the contractile stroke and gravimetric work capacity on the tensile stress.

FIGS. 26A-26B show, respectively, each of the two individual polymer fibers that was extracted from a fabricated 2-ply heterochiral polymer yarn.

FIG. 27 shows the dependence of spring index of ply-extracted coiled fibers on the twist load for the initial twist.

FIGS. 28A-28B shows the dependence of spring index of ply-extracted coiled fibers on the twist load for the plying twist (with twist loads of 18.5 MPa and 73.8 MPa, for FIGS. 28A-28B, respectively).

FIG. 29 shows the measurement of the bias angle of a twisted nylon fiber.

FIG. 30 shows the effect of the second thermal annealing on the spring index of a self-coiled nylon fiber.

FIG. 31 shows the dependencies of spring index, bias angle, and length per coil of thermally-annealed self-coiled fibers on the temperature during the second thermal annealing.

FIGS. 32A-32B show the dependence of contractile stroke and work capacity, respectively, of coiled fibers with different spring indices on the applied tensile stress during actuation.

FIG. 33 shows a multi-spring index coiled fiber fabricated by utilizing a region-selected thermal treatment method.

FIGS. 34A-34D show application of ply-extracted high-spring-index coiled muscles in bilayer textiles. FIG. 34A shows a homochiral ply-extracted high-spring-index coiled muscle.

FIGS. 34B-34C show the morphing of a bilayer textile as the temperature decreases. FIG. 34D shows the cross-sectional area of the buckling of the bilayer textile as a function of temperature.

FIG. 35 shows a two-layer intelligent textile that increases insulation when ply-extracted coiled muscles are used between the two textile layers.

DETAILED DESCRIPTION

A method for fabricating coiled polymer fibers that is less expensive to practice, results in a higher perfection product, and can equally well be extended to coiled nanotube fiber yarns that need not include an agent that adhesively binds together the nanofibers in the yarn, so that the yarn does not untwist or uncoil when removed from the mandrel and untethered. This improved method, which eliminates the need for a mandrel, can be quickly applied for applications where high-spring-index thermally-driven artificial muscles are presently employed, such as for presently commercialized comfort-adjusting jackets. [Ralph Lauren January 2022; Bolder Creative 2022].

Instead of using a mandrel to produce high-spring-index fiber muscles, a method for producing these high-spring-index fiber muscles has been discovered that involves fiber or yarn plying and thermal annealing while in the plied state and demonstrate that a related plying method can be used to make large spring index carbon nanotube yarns that either contain a guest or are guest-free. Additionally, this mandrel-free method can be used to provide high-spring-index yarns and fibers of other materials, such as nickel titanium shape-memory wires.

The methods of embodiments of the present invention for fabricating large-spring-index coiled fiber muscles without use of a mandrel can be applied for any of the many polymers that have sufficiently large volume expansion during actuation for use as a fiber muscle. In addition, the fabrication method for embodiments of the present invention can be used for obtaining large spring index fiber muscles for various electrochemically-driven muscles that need not contain a guest. One good example of this is a carbon nanotube (CNT) yarn that is operated electrochemically by using the volume expansion resulting from electrochemical charge insertion in the electrochemical double layers that form upon applying a potential to a coiled CNT yarn. While small spring index CNT yarns can be conveniently made by inserting sufficient twist to produce coiling in a CNT yarn, this will result in a low spring index yarn whose low spring index limits muscle stroke. On the other hand, twist inserted CNT yarns can be conveniently fabricated as plied yarns. While this is a convenient way to obtain coiled yarns having a high-spring-index because of plying, there are no previously known methods for unplying these yarns without collapse of the high-spring-index coiled structure.

Herein, mandrel-free fabrication of high-spring-index polymer fiber yarns are first described and taught, whether or not these yarns contain a single fiber or a multiplicity of fibers. Before plying, each individual polymer fiber or polymer fiber yarn can optionally be twisted to a desired twist density. Unless otherwise mentioned herein, tensile stresses are normalized to the fiber's or yarn's cross-sectional area at the end of twist insertion, or to N-times this area when N fibers or yarns are plied. During the process of plying together N twisted yarns (or N twisted fibers), these typically one-end-tethered yarns (or fibers) are twisted together by adding plying twist. During the practice of this invention, it is typically very useful to thermally anneal the plied yarn before pulling the individual coiled fibers from the plied yarn.

In some embodiments, this thermal annealing can have import for CNT yarns, in order to avoid the collapse of the high-spring-index structure by causing a degree of binding between individual coiled fibers within the plied yarn, but without causing high binding between different coiled yarns within the plied structure. This thermal annealing process for thermally setting plied CNT yarns can use the incandescent tension anneal process (ITAP) that has previously been deployed for twisted and for coiled CNT yarns. [Di 2016; Di '130 patent]. For some yarn compositions and fabrication methods, it is useful to thermally anneal the ply-extracted yarns one or more times while either non-tethered, tethered torsionally, or tethered both torsionally and in the length direction.

The yarns plied together need not have the same diameter before plying or even contain the same component polymer or nanofiber compositions. In fact, some of the jointly plied yarns can be nanofiber yarns and others can be polymer yarns that need not be nanofiber yarns. Also, the yarns that are plied together can either have the same chirality of inserted twist as the chirality of plying (so they are homochiral) or an opposite chirality of twist (so they are heterochiral). This chirality of plying is identical to the chirality of coiling of the ply-extracted yarn. Also, instead of using thermal setting to retain the coiled structure within the plied structure after yarn extraction from the plied yarn, alternatively, an overcoating structure can be used on the yarns within the ply to retain the coiled structure. Further, alternatively, a combination of an overcoating structure and thermal annealing can be used on the yarns.

Additionally, instead of extracting individual coiled yarns from the plied yarn, more than one yarn can be alternatively extracted from the plied structure, which can have either the same composition and chirality or a different composition or chirality. This use of more than one type of yarn in the plied yarn can enable the simultaneous fabrication of different coiled fiber yarns. Also, extracting two or more neighboring yarns from the plied yarn can provide otherwise unobtainable structures in which polymer coils are well separated by the space originally occupied by presently unextracted yarns.

These coiled yarns that are produced by extraction from the plied yarns can be used for diverse purposes, including as thermally, electrochemically, or material absorption based artificial muscles, as twistocaloric coolers [Wang 2019], and as twistron [Kim 2017] mechanical energy harvesters. These twistocaloric coolers use mechanically-induced entropy changes for refrigeration and these twistron mechanical energy harvesters use stretch-induced, torsionally-induced, or lateral compression-induced changes in the capacitance of conducting nanofibers for converting mechanical energy to electricity.

Again, herein, the discussions and teaching regarding “yarns” and “fibers” related to the present invention can be applied to either yarns or fibers, unless otherwise indicated. When the yarn or fiber is made from a polymer, these can be referred to as a “polymer yarn” or a “polymer fiber.”

As for the term “sacrificial core material” (also referred to as a “sacrificial mandrel”), that is a fiber or other material whose only function is to enable the coiling of another yarn/fiber so that it is usually sacrificial in the sense that it is typically removed by such processes, such as by dissolution in a solvent or thermal depolymerization. [Ridley '979 patent]. This includes that the sacrificial core material/sacrificial mandrel is as a material/mandrel for coiled fiber wrapping that substantially defines the size of the hole within the coiled fiber, but which is sacrificial in the sense that it is not used in the high-spring-index product and is typically removed. In the normal fabrication of a high-spring-index fiber, called mandrel-coiling, the central fiber is usually non-twisted or has a different twist than the fibers being plied.

When the term “tethered” is used, this refers to that both ends of the yarn/fiber are both positionally and torsionally tethered. The term “torsionally tethered” means that opposite fiber ends cannot rotate with respect to each other. The term “positionally tethered” means that opposite fiber ends cannot change their relative position.

The term “spring index” refers to the tightness of the spring's coils. The way to calculate spring index is by dividing (a) the mean diameter of the coils in the spring (outer diameter of the spring minus fiber/yarn diameter or inner diameter of the spring plus fiber/yarn diameter) by (b) the diameter of the fiber/yarn of the spring. A spring with a “high-spring-index” can be more open, with a larger diameter, while a spring with a “low-spring-index” can more closely resemble a tight coil with a small diameter. Generally, having a high-spring-index indicates that the spring index obtained is higher than can obtained by the usual self-coil process wherein a coiled fiber or yarn is produced by inserting twist under a fixed load until the fiber or yarn becomes completely coiled. High-spring-index fibers or yarns generally have a high-spring-index of at least 2, and can have high-spring-index of at least 2.5.

In embodiments of the present invention, the method is for making a high-spring-index fiber or yarn without using a sacrificial core material whose diameter approximately defines the inner-coil diameter. This method includes inserting twist separately into individual fibers or yarns, plying the fibers or yarns by inserting plying twist, setting the ply structure without permanently binding together the fibers or yarns of different plies so that the ply structure is substantially stable against untwist when torsionally untethered, and then unwrapping the plied fibers or yarns so that a high-spring-index fiber or yarn can be obtained. In some embodiments, the unwrapped fibers or yarns are further set so that these are further stabilized.

Improved methods for fabricating coiled polymer fibers and yarns (high-spring-index coiled fiber or yarn) of the present invention are less expensive to practice, result in a higher perfection product, and can equally well be extended to coiled nanotube fiber yarns that need not include an agent that adhesively binds together nanofibers in a yarn, so that the yarn does not untwist or uncoil when removed from the mandrel and untethered. Embodiments of the invention can eliminate the need for a mandrel, and can be quickly applied for applications where high-spring-index thermally-driven artificial muscles are presently employed, such as for presently commercialized comfort-adjusting jackets.

EXAMPLES

The examples provided herein are to illustrate more fully some of the embodiments of the present invention. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the Applicant to function well in the practice of the invention, and thus can be considered to constitute exemplary modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments that are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Example 1

EXAMPLE 1 describes the fabrication of a two-ply polymer yarn in which two fibers have the same diameter and the same chirality. The diameter for these two polymer fibers (nylon-6, fishing line, Eagle Claw Fishing Tackle, Inc.) is 0.28 mm. Unless otherwise mentioned in the examples, the used polymer fiber is nylon-6. Initially, each individual polymer fiber was twist inserted under a tensile load of 18.5 MPa until just below the twist that initiates fiber coiling. These two individual fibers (having the same twist density of 4.4 turns/cm) were torsionally tethered before plying. Here and elsewhere, except when referring to the twist of plying (which is normalized to the twisted fiber's length before plying), the normalizing length corresponds to the length of the non-twisted, non-plied fiber. These fibers were then plied together in the same twist direction as the initial twist to make a 2-ply yarn by using the same tensile load (18.5 MPa), until immediately before the onset of plied yarn coiling (FIG. 1, scale bar: 0.3 mm). To stabilize the plied configuration, this two-end-tethered, 2-ply polymer yarn (having a plying twist density of 4.0 turns/cm) was thermally annealed at ˜160° C. in inert atmosphere or vacuum for 2 hours while fully tethered (positionally and torsionally). By unplying the individual polymer fibers through their end rotation from the opposite-end-tethered two-ply thermally annealed polymer yarn, two individual high-spring-index coiled polymer fibers were obtained. Each polymer fiber had a spring index of 1.52 and a coil bias angle of 59.2° and provided a maximum non-loaded contractile stroke of 7.7% when the temperature was increased from room temperature (22° C.) to 98° C., while the coiled fibers were solely torsionally-tethered. For many samples, the size of this contractile stroke can be dramatically increased by actuating at loads that separates the coils of the high-spring-index yarn, so that coil-coil interference does not prematurely interfere with contraction.

Example 2

EXAMPLE 2 describes the fabrication of a two-ply nylon-6 yarn in which the two fibers have different diameters. Initially, both the thin fiber (diameter: 0.28 mm) and the thick fiber (diameter: 0.90 mm) were twisted in the same direction until just below the twist that initiates fiber coiling. The applied load during pre-plying twisting for the thin and thick polymer fibers were 18.5 MPa and 7.7 MPa, respectively, and the corresponding twist densities were 4.4 turns/cm and 2.4 turns/cm, respectively. For plying, the applied tensile load for each polymer fiber was the same as that for initial twist. In this case, they were plied together in the same twist direction as initial twist until immediately before the onset of plied yarn buckling (FIG. 2). After thermal annealing at ˜160° C. in inert atmosphere or vacuum for 2 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the stabilized 2-ply polymer yarn. This unplying of the individual polymer fibers was through the end rotation of the individual fibers from the opposite-end-tethered two-ply thermally annealed polymer yarn, so two individual high-spring-index coiled polymer fibers were obtained. The thin polymer fiber had a high-spring-index of 7.46 and a coil bias angle of 77.8°, and provides a maximum non-loaded contractile stroke of 57.4% when the temperature was increased from room temperature (22° C.) to 70° C. The thick polymer fiber had a spring index of 2.2 and a coil bias angle of 74.6°, and provides a maximum non-loaded contractile stroke of 10% when the temperature was increased from room temperature (22° C.) to 70° C.

Example 3

EXAMPLE 3 describes the fabrication of a three-ply nylon-6 yarn in which all fibers have the same diameter (0.28 mm) and the same chirality as the chirality of plying. Prior to plying, each of these fibers were isobarically twisted, meaning twisted under the same load, until just below the twist that initiates fiber coiling. The tensile load and twist density for each individual polymer fiber were 18.5 MPa and 4.4 turns/cm. Then, they were plied together under a tensile load of 47.8 MPa in the same twist direction as the initial twist until immediately before the onset of plied yarn buckling or snarling (FIG. 3A). The two-end-tethered plied polymer yarn (having a plying twist density of 6.2 turn/cm) was stabilized by thermal annealing at ˜110° C. in vacuum for 1.5 hours (FIG. 3B). By unplying the individual polymer fibers through their end rotation from the opposite-end-tethered three-ply thermally annealed polymer yarn, three individual high-spring-index coiled polymer fibers were obtained, which were free-standing since they were neither torsionally nor positionally tethered. Since a large ply number typically increases the separation between coils in an individual fiber, a second thermal annealing step was applied while the plied yarn or fiber was non-tethered to decrease this coil separation and enable the fiber to provide reversable muscle actuation. After the first thermal annealing, the non-tethered ply-extracted fibers were annealed at 115° C. in air for 20 seconds (FIG. 3C). The room-temperature length of each of the final ply-extracted fibers decreased by about 60% (relative to the coiled fiber length before the second thermal annealing). Each individual fiber had a high-spring-index of 5.04 and a coil bias angle of 65.7°, and provided a maximum non-loaded contractile stroke of 26.2% when the temperature was increased from room temperature (22° C.) to 105° C.

Example 4

EXAMPLE 4 shows that the performance of a high-spring-index polymer fiber of EXAMPLE 3 as a thermally driven artificial muscle. FIG. 4 shows the dependence of the contractile stroke and gravimetric work capacity on the tensile stress when the temperature was increased from 22 to 105° C. While the contractile stroke of the high-spring-index polymer fiber monotonically decreases with increasing tensile stress (plot 401), the contractile work capacity reached a peak of 13.9 J/kg when a tensile stress of 0.81 MPa was applied during actuation (plot 402).

Example 5

EXAMPLE 5 describes the fabrication of a four-ply nylon-6 yarn in which all fibers have the same diameter (0.28 mm) and the same chirality as the chirality of plying, as well as the use of this 4-ply yarn for making 4 high-spring-index coiled fibers that are not plied. Prior to plying, each of these fibers were isobarically twisted until just below the twist that initiates fiber coiling. The tensile load and twist density for each individual polymer fiber were 18.5 MPa and 4.4 turns/cm. Then, these fibers were plied together under a tensile load of 46.2 MPa in the same twist direction as their initial twist until immediately before the onset of plied yarn buckling or snarling (FIG. 5A). The two-end-tethered plied polymer yarn (having a plying twist density of 4.0 turn/cm) was stabilized by a thermal anneal in vacuum at ˜110° C. for 1.5 hours (FIG. 5B-5C). After this first thermal anneal, the non-tethered ply-extracted fibers were annealed at 115° C. in air for 20 seconds. The room-temperature-length of each of the final ply-extracted fibers decreased by about 60% (relative to the coiled fiber length before the second thermal annealing) (FIG. 5D). Each individual fiber had a high-spring-index of 6.96 and a coil bias angle of 74.2°.

Example 6

EXAMPLE 6 shows the performance of a high-spring-index polymer fiber of EXAMPLE 5 as a thermally-driven artificial muscle. FIG. 6A shows the muscle length change of a coiled fiber that had been extracted from a thermally annealed 4-ply yarn, during a process that first involves a second annealing process at 115° C. in air for 20 seconds and then involves reversible actuation between −15 and 22° C. and between 22 and 105° C. for 10 cycles. The length of the ply-extracted fiber decreased from 68.1 to 18.0 mm during the second thermal annealing, and then elongated to 30.4 mm when the temperature fell to room temperature (22° C.). This thermally-annealed, ply-extracted fiber is a torsionally-stable free-standing muscle, which undergoes reversible tensile thermal actuation without the need for torsional tethering. FIG. 6B shows that the non-loaded, thermally-annealed, ply-extracted fiber provides a contractile stroke of 59.3% when the temperature increased from 22° C. to 105° C., and provides an elongational stroke of 16.1% when the temperature decreased from 22° C. to −15° C.

Example 7

EXAMPLE 7 shows the performance of a high-spring-index polymer fiber of EXAMPLE 5 as a thermally-driven artificial muscle. FIG. 7 shows that both the contractile stroke (plot 702) and the work capacity (plot 702) of the thermally-annealed, ply-extracted fiber of EXAMPLE 5 increases with increasing actuation temperature, and approach plateaus when the actuation temperature exceeds 100° C., due to inter-coil contact. For these tests, a tensile stress of 1.13 MPa was applied to this fiber muscle during actuation. The maximum contractile work capacity of this high-spring-index fiber muscle was about 30 J/kg.

Example 8

EXAMPLE 8 describes the fabrication of four-ply polymer yarns by applying different tensile loads for plying. The diameter for each individual polymer fiber is 0.28 mm. Before plying, all polymer fibers had the same diameter, the same twist density, and the same chirality, and were fabricated by using the method of EXAMPLE 5. Here, a tensile load of either 18.5, 32.3, 46.2, or 60.0 MPa was applied to the polymer yarns during plying. Then, the same first thermal annealing for the plied yarns (which had the same plying twist density of 4.0 turns/cm) and the same second thermal annealing for the ply-extracted fibers of EXAMPLE 5 was used for these polymer yarns. The spring indices (and coil bias angles) for these thermally-annealed ply-extracted fiber muscles were 6.46 (74.6°), 6.73 (74.8°), 6.96 (74.2°) and 8.02 (74.8°), when the plying twist load was 18.5, 32.3, 46.2 and 60.0 MPa, respectively.

Example 9

EXAMPLE 9 shows the actuation performance of the ply-extracted high-spring-index polymer fibers of EXAMPLE 5 and EXAMPLE 8 when the temperature was increased from room temperature (22° C.) to 105° C. FIG. 8A shows that the magnitude of the contractile stroke of these polymer fiber muscles decreases monotonically when the tensile stress during actuation increases from 0 to 1.4 MPa, and approaches zero when the tensile stress exceeds 1.5 MPa. Correspondingly, FIG. 8B shows the dependence of work capacity on tensile stress for the above investigated tensile stress range. When a tensile stress of 0.81 MPa was applied during actuation, the thermally-annealed ply-extracted fiber muscle fabricated using a plying load of 32.3 MPa provided the maximum contractile work capacity (38 J/kg).

Example 10

EXAMPLE 10 describes the fabrication of four-ply polymer yarns by applying different tensile loads for the initial pre-plying twist. The diameter for each individual polymer fiber before twisting was 0.28 mm. Here, tensile loads of 18.5, 36.9, 73.9, and 110.8 MPa were applied on the polymer fiber during this initial twist. All these polymer fibers had the same twist density of 4.4 turns/cm and the same chirality before plying. Then, the same method of EXAMPLE 10 was used for polymer fibers plying, thermal annealing of the plied yarns, and for extracting coiled polymer fibers from the plies. Before thermal annealing, these plied polymer yarns were plied to a twist density of 4.0 turns/cm under a plying tensile load of 32.3 MPa. The spring indices (and coil bias angles) for these thermally-annealed ply-extracted fiber muscles were 6.73 (74.8°), 6.31 (78.87°), 5.18 (81.05°) and 5.0 (85.3°), when the initial twist load was 18.5, 36.9, 73.9 and 110.8 MPa, respectively.

Example 11

EXAMPLE 11 shows the magnitude of actuation for the ply-extracted high-spring-index polymer fibers of EXAMPLE 10 when the temperature was increased from room temperature (22° C.) to 105° C. to provide a contraction and decreased from room temperature (22° C.) to −15° C. to provide an elongation. When the applied twist load for initial twist increased from 18.5 to 73.9 MPa, the elongational stroke of the ply-extracted muscles on going from 22° C. to −15° C. increased by a factor of 2.47, while the contractile stroke on going from 22° C. to 105° C. decreased by a factor of 2.25 (FIG. 9). Therefore, the applied twist load for initial twist can be used to control the maximum actuation strokes of the ply-extracted polymer muscles. However, when much higher tensile loads are used for twist insertion, the sensitivity of stroke to this load and on this temperature change become small. For a load during twist of 73.9 MPa, the ply-extracted muscle provided almost the same elongational stroke (30.4% for this 37° C. temperature decrease) as the contractile stroke (29.6% for this 83° C. temperature increase) for a much larger temperature change. Also, when using an even higher load during twist of 110.8 MPa, the elongational stroke (30.4% for this 37° C. temperature decrease) and the contractile stroke (32.2% for this 83° C. temperature increase) of the ply-extracted muscle were nearly the same as for a twist load of 73.9 MPa.

Example 12

EXAMPLE 12 compares the tensile stress dependence of the actuator performance of the high-spring-index coiled muscles that were made in EXAMPLE 10 for a temperature change from 22 to 105° C. This comparison is for coiled polymer muscles that were made from 4-ply yarn that had the same stress applied during plying (32.3 MPa) and a quite different stress during twist insertion (18.5 and 110.8 MPa) (FIGS. 10A-10B). The muscle made from the 4-ply yarn that had an 18.5 MPa stress during twisting had a contractile stroke (plot 1001) that monotonically decreased with increasing tensile stress from 68% at zero stress to nearly 0% at 1.7 MPa and a maximum contractile work capacity (plot 1011) of 40 J/kg that peaked for a 0.85 MPa tensile stress during actuation. In contrast, the coiled polymer muscle that was made from the 4-ply yarn that had a 110.8 MPa stress during twisting had a maximum contractile stroke (plot 1002) of 41% that peaked at 0.85 MPa tensile stress during actuation and a maximum contractile work capacity (plot 1012) of 68.6 J/kg that peaked at 2.7 MPa tensile stress during actuation.

Example 13

EXAMPLE 13 describes the fabrication of four-ply polymer yarns by applying different twist densities for the initial pre-plying twist. The diameter for each individual polymer fiber before twisting was 0.28 mm. Here, twist densities of 0.16, 1.56, 3.12, 4.0, 4.40, 5.31, and 6.25 turns/cm were applied on the polymer fiber during this initial twist. All these polymer fibers had the same twist load of 110.8 MPa and the same chirality before plying. Then, these polymer yarns with the same twist density were plied to a plying twist density of 4.0 turns/cm under a plying tensile load of 32.3 MPa. Here, the method of EXAMPLE 5 was used for thermal annealing the plied yarns and for extracting coiled polymer fibers from the plies.

Example 14

EXAMPLE 14 shows the magnitude of actuation (when no load was applied) for the ply-extracted high-spring-index polymer fibers of EXAMPLE 13 when the temperature was increased from room temperature (22° C.) to 105° C. to provide a contraction and decreased from room temperature (22° C.) to −15° C. to provide an elongation. When the twist density for initial twist was increased from 0.16 to 6.25 turns/cm, the elongational stroke of the ply-extracted muscles on going from 22° C. to −15° C. increased from 0.6 to 30.4%, while the contractile stroke on going from 22° C. to 105° C. reached a peak of 46.7% at a twist density of 5.31 turns/cm (FIGS. 11A-11B). Therefore, the applied twist density for initial twist can be used to maximize the actuation stroke of the ply-extracted polymer muscles. When much higher fiber twist densities (>6.25 turns/cm) were used for twist insertion, one or more individual highly twisted polymer fibers fractured during plying. Therefore, a twist density of 6.25 turns/cm was used as the maximum twist density during twist insertion for these polymer fibers under the fabrication conditions of EXAMPLE 13.

Example 15

EXAMPLE 15 describes the effect of varying the second annealing temperature on the performance of a four-ply-extracted coiled fiber. The diameter of each individual polymer fiber before twisting was 0.28 mm. For initial pre-plying twist insertion, each individual polymer fiber was twisted to a twist density of 3.12 turns/cm under a tensile load of 110.8 MPa. Then, these twisted polymer fibers were plied to a plying twist density of 4.0 turns/cm under a plying tensile load of 32.3 MPa. After the first thermal annealing in vacuum at ˜110° C. for 1.5 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the stabilized 4-ply polymer yarn. Then, the non-tethered ply-extracted fibers were divided into two parts, one part were annealed in air at 115° C. for 20 seconds and the other part were annealed in air at 150° C. for 20 seconds. The ply-extracted coiled fibers undergoing a second anneal at 115° C. had a high-spring-index of 6.31 and a coil bias angle of 62.0°, while the other ply-extracted coiled fibers undergoing a second anneal at 150° C. had a high-spring-index of 8.69 and a coil bias angle of 72.7°.

Example 16

EXAMPLE 16 shows the magnitude of actuation for the ply-extracted high-spring-index polymer fibers of EXAMPLE 15 when the temperature was increased from room temperature (22° C.) to 105° C. to provide a contraction and decreased from room temperature (22° C.) to −15° C. to provide an elongation. The ply-extracted coiled fiber undergoing a second anneal at 150° C. provided a reversible contractile stroke of 42.5% for a temperature increase from 22° C. to 105° C., which was 2.5 times that of ply-extracted coiled fibers undergoing a second anneal at 115° C. In addition, the maximum elongational stroke of the ply-extracted coiled fiber undergoing a second anneal at 150° C. was 10.0% for a temperature decrease from 22° C. to −15° C., while the maximum elongational stroke of the ply-extracted coiled fiber undergoing a second anneal at 115° C. was 4.4% (FIG. 12).

Example 17

EXAMPLE 17 shows the temperature dependence of the non-loaded contractile stroke of the ply-extracted high-spring-index polymer fibers of EXAMPLE 15 during actuation. The contractile stroke of both coiled polymer fibers increased monotonically with increasing actuation temperature. The ply-extracted coiled fiber undergoing a second anneal at 115° C. (plot 1301) provided a maximum reversible contractile stroke of 17.0% at 105° C., while the ply-extracted coiled fiber undergoing a second anneal at 150° C. (plot 1302) provided a contractile stroke of 42.5% at the same actuation temperature and a maximum contractile stroke of 81.2% when temperature was increased from 22 to 143° C. (FIG. 13). This result indicates that an optimized temperature during thermal annealing can be used to maximize the actuation stroke of the ply-extracted polymer muscles.

Example 18

EXAMPLE 18 shows the tensile stress dependence of the contractile stroke and contractile work capacity of the ply-extracted high-spring-index polymer fibers of EXAMPLE 15 during actuation. The contractile stroke of these coiled polymer fibers which undergo either a second anneal at 115° C. or at 150° C. decreased monotonically with increasing tensile stress. In this case, the temperature was increased from 22 to 105° C. for the ply-extracted coiled fibers undergoing either a second anneal at 115° C. (plot 1401) or at 150° C. (plot 1402) (FIG. 14A). In addition, the temperature was increased from 22 to 143° C. for the ply-extracted coiled fiber undergoing a second anneal at 150° C. (plot 1403). When a tensile stress of 0.81 MPa was applied, the ply-extracted coiled fiber undergoing a second anneal at 115° C. provided a maximum contractile work capacity of 18.0 J/kg at 105° C. (plot 1411), while the ply-extracted coiled fiber undergoing a second anneal at 150° C. (plot 1412) provided a contractile work capacity of 22.1 J/kg for the same actuation temperature and a maximum contractile work capacity of 31.7 J/kg when temperature is increased from 22 to 143° C. (plot 1413) (FIG. 14B).

Example 19

EXAMPLE 19 describes the fabrication of a three-ply CNT yarn in which all individual yarns have the same diameter (about 100 μm after twist insertion but before plying) and the same chirality as the chirality of plying. Prior to plying, each of these individual yarns were isobarically twisted until just below the twist that initiates yarn coiling. The tensile load and twist density for each individual CNT yarn was 38 MPa and 30 turns/cm. Then, these yarns were plied together under the same tensile load of 38 MPa in the same twist direction as the initial twist until immediately before the onset of plied yarn coiling (FIG. 15A). The two-end-tethered plied CNT yarn (having a plying twist density of 17 turn/cm) was stabilized by using the incandescent tension anneal process (ITAP) for electrothermal pulse annealing under tension (about 3000° C. for 120 s under 38 MPa). By unplying the individual CNT yarns, through their end rotation from the opposite-end-tethered three-ply ITAP annealed CNT yarn, three individual high-spring-index coiled CNT yarns were obtained, which were free-standing since they were neither torsionally nor positionally tethered (FIGS. 15B-15C). Each individual coiled yarn had a high-spring-index of 1.67.

Example 20

EXAMPLE 20 shows the adsorption-driven actuation performance of the ply-extracted high-spring-index CNT yarn of EXAMPLE 19 when methanol was adsorbed and desorbed from the yarn during its use as a methanol-adsorption-powered muscle. FIG. 16 shows the dependence of the contractile stroke (plot 1601) and gravimetric work capacity (plot 1602) on the tensile stress. While the magnitude of the contractile stroke of the CNT yarn muscle decreases monotonically from 21.4% to 1.2% when the tensile stress during actuation increased from 0 to 2.3 MPa, the contractile work capacity reached a peak of 55 J/kg when a tensile stress of 1.1 MPa was applied during actuation.

Example 21

EXAMPLE 21 shows the performance of a high-spring-index CNT yarn of EXAMPLE 19 as an electrochemical-driven artificial muscle in an electrolyte of 0.2 M tetrabutylammonium hexafluorophosphate (TBA·PF₆) in propylene carbonate (PC). FIG. 17A shows that the stress-free contractile stroke of the ply-extracted CNT yarn muscle increases with increasing applied inter-electrode voltage, and reaches a maximum stroke of 18.5% for an applied voltage of −3.25 V (plot 1701). FIG. 17B shows the dependence of the contractile stroke (plot 1711) and gravimetric work capacity (plot 1712) on the tensile stress when the applied inter-electrode voltage was −3.25 V. While the contractile stroke of the high-spring-index CNT yarn monotonically decreases with increasing tensile stress, the contractile work capacity reached a peak of 44.8 J/kg when a 1.2 MPa tensile stress was applied during actuation.

Example 22

EXAMPLE 22 describes the fabrication of a 2-ply polyurethane yarn in which all individual yarns have the same diameter (about 398 μm after twist insertion but before plying) and the same chirality as the chirality of plying. Prior to plying, each of these individual yarns were isobarically twisted until just below the twist that initiates yarn coiling. The tensile load and twist density for each individual polyurethane yarn was 4.73 MPa and 9 turns/cm. Then, these fibers were plied together under a tensile load of 4.73 MPa in the same twist direction as their initial twist until immediately before the onset of plied yarn buckling or snarling. The two-end-tethered plied polymer yarn (having a plying twist density of 8 turns/cm) was stabilized by a thermal anneal in vacuum at ˜160° C. for 1.5 hours (FIG. 18A). After this thermal anneal and extraction of the individual coiled fibers, each individual fiber had a spring index of 1.85 and a coil bias angle of 30.2° (FIG. 18B).

Example 23

EXAMPLE 23 shows the performance of a coiled fiber of EXAMPLE 22 as a thermally driven artificial muscle. FIG. 19 shows the dependence of the tensile stroke (plot 1901) and gravimetric work capacity (plot 1902) on the applied tensile stress when the temperature was decreased from 25 to −30° C. While the tensile stroke of the polymer fiber monotonically decreases with increasing tensile stress, from a maximum value of 39%, the tensile work capacity reached a peak of 53.48 J/kg when a tensile stress of 0.29 MPa was applied during actuation.

Example 24

EXAMPLE 24 describes the effect of a second high-temperature thermal annealing time on the performance of the polymer fiber prepared in EXAMPLE 22. After the first thermal annealing in vacuum at ˜160° C. for 1.5 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the thereby stabilized 2-ply polymer yarn. Then, the retethered ply-extracted fiber was annealed in air at 160° C. for 0.5 to 5 hours. FIG. 20 shows the dependence of the tensile stroke (plot 2001) and gravimetric work capacity (plot 2002) on the tensile stress when the temperature was decreased from 25 to −30° C. after a second annealing of 1 hour. While the tensile stroke of the polymer fiber monotonically decreases with increasing tensile stress, from a maximum value of 61%, the tensile work capacity reached a peak of 69.22 J/kg when a tensile stress of 0.37 MPa was applied during actuation.

Example 25

EXAMPLE 25 shows the dependence of actuation, for a temperature change from 25 to −30° C., on the length of the second high-temperature thermal annealing time. Both tensile stroke and work capacity were maximized by applying 1 hour of anneal at ˜160° C. to the ply-extracted fibers (FIGS. 21A-21B). However, as shown, there was little change in either tensile stroke or work capacity when the anneal time at ˜160° C. was increased from 1.5 hours to 2 hours. The second annealing decreased the initial length of the polymer yarn (FIG. 21C), resulting in improved actuation performance. Compared to the polymer yarn before the second annealing, the work capacity increased by about 30% (FIG. 21D).

Example 26

EXAMPLE 26 describes the effect of varying the second annealing temperature on the performance of a two-ply extracted coiled nylon-6 fiber. The diameter of each individual polymer fiber before twisting was 0.28 mm. For initial pre-plying twist insertion, each individual polymer fiber was twisted to a twist density of 5.0 turns/cm under a tensile load of 73.9 MPa. Then, these twisted polymer fibers were plied to a plying twist density of 5.4 turns/cm under a plying tensile load of 64.6 MPa. After the first thermal annealing in vacuum at ˜110° C. for 1.5 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the stabilized 2-ply polymer yarn. Then, the non-tethered ply-extracted fibers were divided into seven parts, which were thermally annealed in air for 20 seconds at 115° C., 132° C., 150° C., 166° C., 182° C., 193° C. and 205° C., respectively.

Example 27

EXAMPLE 27 shows the dependencies of spring index, coil bias angle, and length per coil of ply-extracted coiled fibers of EXAMPLE 26 on the second annealing temperature. Here, the length per coil is defined as the fiber length between neighboring coils. When the second annealing temperature was increased from 115 to 193° C., both the spring index (plot 2201) and the coil bias angle (plot 2202) of the ply-extracted coiled fibers increased and reached the following peaks (spring index: 5.89; coiled bias angle: 75.1°) for an annealing temperature of 193° C. (FIG. 22). A higher annealing temperature of 205° C. decreased the spring index and the coiled bias angle. In contrast, the coil-to-coil separation distance of these ply-extracted coiled fiber (plot 2203) showed only small variations within the above annealing temperature range.

Example 28

EXAMPLE 28 shows the magnitudes of actuation stroke for the ply-extracted high-spring-index polymer fibers of EXAMPLE 26 when the temperature was increased from room temperature (22° C.) to 105° C. to provide a contraction and decreased from room temperature (22° C.) to −15° C. to provide an elongation. The ply-extracted coiled fiber that underwent a second anneal at 193° C. provided a maximum reversible contractile stroke of 45.2% for a temperature increase from 22° C. to 105° C., which was larger than that for other second annealing temperatures and was over 6 times that of ply-extracted coiled fibers that underwent a second anneal at 115° C. (FIG. 23, plot 2301). In addition, the maximum elongational stroke of the ply-extracted coiled fiber undergoing a second anneal at 193° C. was 12.8% for a temperature decrease from 22° C. to −15° C., while the maximum elongational stroke of the ply-extracted coiled fiber undergoing a second anneal at 115° C. was 1.9%, and all other second annealing temperatures provided a smaller stroke than did the sample having a second annealing temperature of 193° C. (FIG. 23, plot 2302). Hence, the sample having a second annealing temperature of 193° C. provided both a larger magnitude stroke than for samples having a different second annealing temperature for both temperature increases from room temperature (22° C.) to 105° C. and for temperature decreases from room temperature (22° C.) to −15° C. As shown in FIG. 23, the stroke magnitude increases in going from a second annealing temperature of 115° C. to 193° C. is quite large (a factor of about 6.1 increase in muscle length in going from 22 to −15° C. (plot 2302) and a factor of about 6.5 decrease in muscle length in going from 22 to 105° C. (plot 2301)). Furthermore, increase of the annealing times (from 1 min. to 10 min.) at the second anneal temperature had little effect on the actuation strokes for these two temperature ranges.

Example 29

EXAMPLE 29 shows in FIG. 24 the temperature dependence second-anneal-temperature-optimized contractile stroke of a high-spring-index polymer fiber of EXAMPLE 26. The second annealing temperature for this 2-ply extracted polymer fiber was 193° C. FIG. 24 shows that the contractile stroke of the thermally-annealed, ply-extracted fiber increases with increasing actuation temperature, and approaches a plateau when the actuation temperature exceeds 166° C. This plateau is due to inter-coil contact.

Example 30

EXAMPLE 30 describes the performance of a high-spring-index polymer fiber of EXAMPLE 26 as a thermally driven artificial muscle. The performance-optimized second annealing temperature for this ply-extracted polymer fiber is 193° C. FIG. 25 shows the dependence of the contractile stroke (plot 2501) and gravimetric work capacity (plot 2501) on the tensile stress when the temperature was increased from 22 to 182° C. While the contractile stroke of the high-spring-index polymer fiber monotonically decreases with increasing tensile stress, the contractile work capacity reached a peak of 133.2 J/kg when a tensile stress of 1.92 MPa was applied during actuation.

Example 31

EXAMPLE 31 describes the fabrication of two-ply heterochiral polymer yarns in which two fibers have the same diameter and the same chirality. The initial diameter for these two polymer fibers was 0.28 mm. Initially, each individual polymer fiber was twisted to a twist density of 5.0 turns/cm under a tensile load of 73.9 MPa. These fibers were then plied together to a twist density of 7.1 and 10.0 turns/cm, respectively, in the opposite twist direction as the initial twist to make 2-ply heterochiral yarns by using a tensile load of 64.6 MPa during plying. To stabilize the plied configuration, these two-end-tethered, 2-ply heterochiral polymer yarns were thermally annealed at ˜120° C. in vacuum for 2 hours while fully tethered (positionally and torsionally). Then, each individual polymer fiber was extracted from the 2-ply heterochiral polymer yarns (FIGS. 26A-26B). The ply-extracted coiled fiber made by inserting a plying twist density of 10.0 turns/cm provided a maximum reversible elongational stroke of 3.4% for a temperature increase from 22° C. to 105° C., which was over 4 times that of ply-extracted coiled fibers made by inserting a plying twist density of 7.1 turns/cm. However, the maximum contractile stroke for these ply-extracted coiled polymer fibers was below 1% for a temperature decrease from 22° C. to −15° C., for any value of the plying twist density between 7.1 and 10.0 turns/cm.

Example 32

EXAMPLE 33 describes the fabrication of two-ply polymer yarns by applying different tensile loads for the initial twist. The diameter for each individual polymer fiber before twisting was 0.28 mm. Here, tensile loads of 18.5, 36.9, 55.4, 73.9, 110.8 and 129.3 MPa were applied on the polymer fiber during this initial twist. All these polymer fibers had the same twist density of 5.0 turns/cm and the same chirality before plying. During plying, the twist density and twist load were 5.4 turns/cm and 64.6 MPa. After the first thermal annealing in vacuum at ˜110° C. for 1.5 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the stabilized 2-ply polymer yarns. Then, the non-tethered ply-extracted fibers derived from different twist loads were thermally annealed in air for 20 seconds at 115° C. and 193° C., respectively.

Example 33

EXAMPLE 33 shows the dependence of spring index of ply-extracted coiled fibers of EXAMPLE 32 on the twist load for the initial twist. For the ply-extracted coiled fibers treated by either second thermal annealing (plots 2701-2701 for, respectively, 193° C. and 115° C. thermal annealing) or not (plot 2701), the spring index of these ply-extracted coiled fibers monotonically decreased when the twist load increased from 18.5 to 129.3 MPa (FIG. 27). By applying the lowest twist load of 18.5 MPa during initial twist, the ply-extracted coiled fiber provided a maximum spring index of 5.5 after thermal annealing at 193° C. for 20 seconds.

Example 34

EXAMPLE 34 describes the fabrication of two-ply polymer yarns by applying different tensile loads for plying twist. The diameter for each individual polymer fiber before twisting was 0.28 mm. Before plying, the individual fibers were inserted twist to a twist density of 5.0 turns/cm under a tensile load of 18.5 MPa. All these polymer fibers had the same chirality. Then, these fibers were plied to a twist density of 5.4 turns/cm under tensile loads of 18.5, 27.7, 36.9, 46.2, 55.4 and 64.6 MPa, respectively. After the first thermal annealing in vacuum at ˜110° C. for 1.5 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the stabilized 2-ply polymer yarns. Then, the non-tethered ply-extracted fibers derived from different twist loads were thermally annealed in air for 20 seconds at 115° C. Similarly, a tensile load of 73.8 MPa for initial twist was applied to the individual fibers for making two-ply polymer yarns by using the same parameters shown above.

Example 35

EXAMPLE 35 shows the dependence of spring index of ply-extracted coiled fibers of EXAMPLE 34 on the twist load for the plying twist. For the twist loads of 18.5 (FIG. 28A with plots 2801-2802 for after 115° C. thermal annealing and no second thermal annealing, respectively) and 73.8 MPa (FIG. 28B with plots 2811-2812 for after 115° C. thermal annealing and no second thermal annealing, respectively) for initial twist, the spring index of the ply-extracted coiled fibers was little affected by varying the plying tensile load within the investigated range. These results indicated that the spring index of the ply-extracted coiled fibers is mainly dominated by the twist load for initial twist rather than the twist load for plying twist.

Example 36

EXAMPLE 36 shows the measurement of the bias angle of a twisted nylon fiber. Before twist insertion, a nylon fiber 2901 was marked by a red line (shaded line) 2902 along the fiber direction. (FIG. 29). Segment 2903 of a nylon fiber 2901 is shown in magnified view. For a given twist, the red line (shaded line) 2902 on the nylon fiber 2701 would reflect the bias angle 2907 change. By inserting twist to a twist density of 5.0 turns/cm under a tensile load of 73.8 MPa, the nylon fiber provided a bias angle of 23.2° (FIG. 29).

Example 37

EXAMPLE 37 describes the effect of the second thermal annealing on the spring index of a self-coiled nylon fiber. The diameter for the individual polymer fiber before twisting was 0.28 mm. The single fiber was inserted twist to a twist density of 13.3 turns/cm under a tensile load of 18.5 MPa to obtain a fully self-coiled fiber. After the first thermal annealing in vacuum at ˜110° C. for 1.5 hours, the tethering for this self-coiled fiber was completely removed. This free-standing self-coiled nylon fiber 3001 (with cross-section 3002) provided a small spring index of 1.69 (FIG. 30). By applying a second thermal annealing at 193° C. for 20 seconds, the spring index of this coiled fiber 3011 (with cross-section 3012) increased to 2.62, and each coil still fully contacted the neighboring coils (FIG. 30).

Example 37

EXAMPLE 38 shows the dependence of spring index, bias angle and length per coil of the thermal-annealed self-coiled fibers on the temperature during second thermal annealing. Here, the length per coil is the fiber length between neighboring coils, which is calculated from Eq.(1):

$\begin{array}{cc}{L}_{coil}=\frac{\pi d\left(\mathrm{SI}\right)}{\sin \left(\alpha \right)}& \left(1\right)\end{array}$

where d is the fiber diameter, SI is the coil spring index, and the a is the coiled bias angle.

With increasing the temperature, the spring index (plot 3101), bias angle (plot 3102), and length per coil (plot 3103) monotonically increased and reached a maximum at the temperature at 193° C. (FIG. 31). This result indicates that additional thermal treatment also can be used to increase the spring index for a self-coiled fiber.

Example 39

EXAMPLE 39 shows the dependence of contractile stroke and work capacity of coiled fibers on the applied tensile stress during actuation. Here, the temperature was increased from room temperature (22° C.) to 105° C. to provide a contraction for these coiled nylon fibers. From the results shown in FIGS. 32A-32B, the fully self-coiled fiber with the smallest spring index of 1.69 provided a maximum work capacity of 588.1 J/kg when a tensile stress of 29.6 MPa was applied, which produce a contractile stroke of 10.4%. The maximum contractile stroke of 12.9% for this self-coiled fiber was obtained at a tensile stress of 18.5 MPa. In contrast, the ply-extracted fiber with a spring index of 8.02 provided a maximum non-loaded stroke of 81.1% and a large load stroke of 69.1% for a very small tensile stress of 0.07 MPa. While this high-spring index coiled fiber provided a maximum tensile stress-optimized work capacity of 16.4 J/kg when a tensile stress of 0.44 MPa was applied. This work capacity is much smaller than for the self-coiled fiber. As indicated from the curves, larger spring index would decrease the work capacity but dramatically increase the contractile stroke that is very important for the applications that need large strokes.

Example 40

EXAMPLE 40 describes the fabrication of a multi-spring index coiled fiber by utilizing a region-selected thermal treatment method. The diameter for each individual polymer fiber is 0.28 mm. Initially, individual fiber was twist inserted to a twist density of 5.0 turns/cm under a tensile load of 73.8 MPa. Then, these individual polymer fibers were plied to a twist density of 5.4 turns/cm under a tensile load of 64.6 MPa for making a two-ply polymer fiber. After the first thermal annealing in vacuum at ˜110° C. for 1.5 hours, the tethering was completely removed, and the individual coiled fibers were extracted from the stabilized two-ply polymer yarns. Then, three different temperatures of 115° C., 193° C. and 127° C. were used to thermally treat the different regions in the coiled fiber direction, respectively, which results in multi-spring indices of 2.31, 5.88, and 2.92 in this coiled fiber at regions (or segments) 3301-3303, respectively (FIG. 33). During thermal treatment on a selected region, the other regions of the coiled fiber were torsionally and positionally tethered.

Example 41

EXAMPLE 41 describes the application of the ply-extracted high-spring-index coiled muscles of the present invention in bilayer textiles that are used for comfort-adjusting jackets, which become increasingly insulating when the temperature decreases, but do not morph to change the insulation when it becomes hot. Such bilayer comfort-adjusting textile can also be used for many other applications, such as quilts, sleeping bags, tent fabrics, and trousers. This increased insulation results in the simplest case since the large spring index muscles are sewn in the outer faces of a two-layer textile, so the expansion of these artificial muscles during cooling causes these two layers to separate and thereby open up insulating air voids in the textile.

As used herein, in a two-layer textile, each of the layers has a face that is facing the other layer (which are referred to as the “inner faces” of the two layers) and each of the layers has an opposite face that is facing away from the other layer (which are referred to as the “outer faces” of the two layers). Being on or between the inner faces of the two layers is referred to as being on or between the two layers. Being on or outside the outer faces of the two layers is referred to as being on or outside the two layers. Again, in this EXAMPLE 41, the large spring index muscles are sewn in the outer faces of a two-layer textile such that the large spring index muscles are on or outside the two layers.

The actuation of this textile that deploys the ply-extracted high-spring-index coiled muscles is shown in FIGS. 34A-34D. FIG. 34A shows one of the used homochiral ply-extracted polymer muscles. FIGS. 34B-34C show planar textile 3401 and the morphing to morphed textile 3402 to increase insulation as the temperature decreases from 24 to −11° C. FIG. 34D shows the cross-sectional area of the buckling (which opens the insulating air voids, such as in morphing textile 3402) as a function of temperature. The specific geometry that has been previously used for jackets that deploy mandrel-coiled polymer muscles [Ridley '979 patent] is described in a Ridley '188 Application. This homochiral geometry can be used for the less-expensive produced mandrel-free-fabricated ply-extracted coiled muscles of the present invention to make a textile that become more thermally insulating when temperature decreases. Also, the mandrel-free-fabricated ply-extracted coiled heterochiral muscles (such as shown in EXAMPLE 31) can be deployed in the previously used weave of Ridley '188 application to make an actuating textile that becomes more insulating when heated.

As used herein, unless otherwise indicated, insulation is referring to thermal insulation, i.e., the resistance to conductive heat flow, which is measured in terms of thermal resistance or R-value. R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux between the warmer surface and colder surface of a barrier (such as a bi-layer textile) under steady-state conditions. The higher the R-value, the greater the insulating effectiveness. A change of the R-value is a change of insulation. I.e., an increase of the R-value is an increase of insulation, and a decrease of the R-value is a decrease of insulation. In some embodiments, the change of insulation is a change of at least 5% of the R-value. In further embodiments, the change of insulation is a change of at least 10% of the R-value.

Example 42

EXAMPLE 42 describes the configuration of the present invention for a two-layer intelligent textile that increases insulation during heating when homochiral ply-extracted coiled muscles are used on and between these two layers and increases insulation during cooling when heterochiral ply-extracted coiled muscles are used between these two layers. FIG. 35 provides images taken of the planar sheet structure 3501 at room temperature and the highly morphed sheet structure 3502 at −7° C. Stacks of these new configurations containing alternating two-layer textiles having these different chiral structures can provide a stack that could be used to provide intelligent insulation for a building by increasing insulation when either it becomes too hot or it becomes too cold outside.

While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described and the examples provided herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Accordingly, other embodiments are within the scope of the following claims. The scope of protection is not limited by the description set out above.

The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated herein by reference in their entirety, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

Amounts and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly recited limits of 1 to approximately 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than approximately 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described. The symbol “˜” is the same as “approximately”.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

Following long-standing patent law convention, the terms “a” and “an” mean “one or more” when used in this application, including the claims.

Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

As used herein, the term “and/or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and/or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.

REFERENCES

• U.S. Pat. No. 10,837,130, entitled “Incandescent Tension Annealing Processes For Strong, Twisted-Stable Carbon Nanotube Yarns And Muscles,” issued Oct. 28, 2020, to J. Di, et al. (“Di '130 patent”)
• U.S. Pat. No. 10,793,979, entitled “Coiled Actuator System And Method,” issued Sep. 16, 2020, to B. Ridley, et al. (“Ridley '979 patent”)
• U.S. Patent Appl. Publ. No. 2019/0269188, entitled “Thermally Adaptive Fabrics A filed Mar. 5, 2019, to B. Ridley, et al. (“Ridley '188 application”).
• Bolder Creative article/advertisement, “Ralph Lauren ‘Insulation’ 2022 Winter Olympics, Jan. 25, 2022, available at website “www.Ibbonline.com” on webpage “work/61727” (“Bolder Creative 2022”).
• Di, J., et al., “Strong, Twist-Stable Carbon Nanotube Yarns And Muscles By Tension Annealing At Extreme Temperatures,” Advanced Materials, 2016, 28, 6598-6605 (“Di 2016”).
• Kim, S. K., et al., “Harvesting Electrical Energy From Carbon Nanotube Yarn Twist,” Science, 2017, 357, 773-778 (“Kim 2017”).
• Ralph Lauren press Rrelease, “Ralph Lauren Debuts ‘Intelligent Insulation’ Technology, A Pioneering Apparel Innovation Developed For Team Usa's Opening Ceremony Parade Uniform,” Jan. 20, 2022, available at website “www.corporate.ralphlauren.com” on webpage “pr_220120_BeijingOlympics.html” (“Ralph Lauren January 2022”).
• Wang, R., et al., “Torsional Refrigeration By Twisted, Coiled, And Supercoiled Fibers,” Science, 2019, 366, 216-221 (“Wang 2019”).

Claims

1. A method for making a high-spring-index coiled fiber or yarn without using a sacrificial core material whose diameter approximately defines the inner-coil diameter, wherein the method comprises: (a) inserting twist separately into two or more individual fibers and/or yarns;(b) plying the two or more individual fibers and/or yarns by inserting plying twist to form a multi-ply structure;(c) setting the multi-ply structure without permanently binding together the two or more individual fibers and/or yarns of different plies in the multi-ply structure so that the multi-ply structure is substantially stable against untwist when torsionally untethered, and(d) after the step of setting, unwrapping the two or more individual fibers and/or yarns of different plies in the multi-ply structure to obtain the high-spring-index fiber or yarn.

2. The method of claim 1, wherein the step of setting comprises a process selected from the group consisting of thermal annealing, exposure to actinic radiation, exposure of the two or more individual fibers and/or yarns to an absorbed liquid, infiltration of a binding agent into the two or more individual fibers and/or yarns, and combinations thereof.

3. The method of claim 1, wherein the step of setting comprises a thermal annealing process.

4. The method of claim 1, wherein (a) the two or more individual fibers and/or yarns comprise a carbon nanotube yarn; and(b) the step of setting comprises thermal setting comprising an incandescent tensile annealing process.

5. The method of claim 1, wherein (a) the two or more individual fibers and/or yarns comprises an individual fiber and an individual yarn;(b) at least one of the individual fiber and the individual yarn is selected from the group consisting of elastomeric polymers, non-elastomeric polymers, metal wires, metal yarns, carbon fibers, carbon yarns, carbon nanotube yarns, and combinations thereof.

6. The method of claim 1, wherein (a) the two or more individual fibers and/or yarns comprise at least one individual fiber or yarn that has different characteristic to at least one other individual fiber or yarn; and(b) the different characteristic is selected from the group consisting of a different diameter, a different amount of twist, an opposite chirality of twist, and combinations thereof.

7. The method of claim 1, wherein all of the two or more individual fibers and/or yarns have a same diameter, a same amount of twist, and a same chirality of twist to each of the other two or more individual fibers.

8. The method of claim 1, wherein the two or more individual fibers and/or yarns comprise a metal wire or yarn.

9. The method of claim 8, wherein the metal wire is a shape-memory metal wire or yarn.

10. The method of claim 1, wherein (a) the step of unwrapping the two or more individual fibers and/or yarns obtains two or more high-spring-index fibers and/or yarns,(b) the two or more individual fibers and/or yarns used in the method become the two or more high-spring-index fibers and/or yarns extracted from the multi-ply structure.

11. The method of claim 1, wherein (a) the two or more individual fibers and/or yarns comprises at least one polymer fiber or polymer yam;(b) the at least one polymer fiber or polymer yarn comprises a polymer;(c) the step of setting comprises subjecting the at least one polymer fiber or yarn to a first thermal annealing process;(d) the thermal annealing process is conducted at a temperature above glass transition temperature of the polymer and below melting point of the polymer; and(e) the thermal annealing process is conducted while the multi-plied structure is tethered.

12. The method of claim 11 further comprising, after the step of unwrapping, performing a second thermal annealing process in which the high-spring-index coiled fiber is thermally annealed when not torsionally or positionally tethered.

13. The method of claim 12, wherein the second thermal annealing process is performed at a temperature that is above the glass transition temperature of the polymer, below the melting point of the polymer, and above the temperature of the first thermally annealing process.

14. The method of claim 1, wherein (a) each of the two or more individual fibers and/or yarns comprise polymers, and(b) each of two or more individual fibers and/or yarns are unwrapped from the multi-ply structure as high-spring-index fibers and/or yarns.

15. The method of claim 1, wherein (a) the two or more individual fibers and/or yarns comprises three or more individual fibers and/or yarns;(b) the step of unwrapping comprises that at least two, but not all, of the three or more individual fibers and/or yarns are unwrapped from the multi-ply structure without unwrapping them from one another to obtain the high-spring-index fiber or yarn.

16. The method of claim 1, wherein the setting of the multi-ply structure is region specific, such that different regions of the multi-ply structure are differently set.

17. The method of claim 16, where the setting comprises a region-selected thermal treatment process.

18. The method of claim 1, wherein the high-spring-index fiber and/or yarn has a spring index of at least 2.

19. The method of claim 18, wherein the spring index is at least 2.5.

20. A method comprising: (a) selecting a plurality of high-spring-index coiled fibers and/or yarns, wherein each high-spring-index coiled fiber and/or yarn in the plurality is made by the method of claim 1; and(b) fabricating a two-layer textile by incorporating the plurality of high-spring-index coiled fibers and/or yarns into the two-layer textile, wherein the two-layer textile changes insulation when ambient temperature changes.

21. The method of claim 20, wherein, (a) the two-layer textile has a first layer and a second layer, wherein (i) the first layer has a first-layer inner face and a first-layer outer face,(ii) the second layer has a second-layer inner face and a second-layer outer face,(iii) the first-layer inner face and the second-layer inner face are facing toward one another, and(iv) the first-layer outer face and the second-layer outer face are facing away from one another;(b) the incorporating of the plurality of high-spring-index coiled fibers and/or yarns into the two-layer textile comprises a tailoring process selected from the group consisting of sewing, stitching, embroidering, weaving, and combinations thereof;(c) a first portion of the high-spring-index coiled fibers and/or yarns are on or outside the first-layer outer face and a second portion of the high-spring-index coiled fibers and/or yarns are on or outside the second-layer outer face, such that the high-spring-index coiled fibers and/or yarns are incorporated as artificial muscles on or outside the first layer and the second layer; and (d) the artificial muscles are either (i) homochiral to increase the insulation of the two-layer textile when the ambient temperature gets colder than a desired temperature or (ii) heterochiral to increase the insulation of the two-layer textile when the ambient temperature gets warmer than the desired temperature.

22. The method of claim 20, wherein, (a) the two-layer textile has a first layer and a second layer, wherein (i) the first layer has a first-layer inner face and a first-layer outer face,(ii) the second layer has a second-layer inner face and a second-layer outer face,(iii) the first-layer inner face and the second-layer inner face are facing toward one another, and(iv) the first-layer outer face and the second-layer outer face are facing away from one another;(b) a first portion of the high-spring-index coiled fibers and/or yarns are on or inside the first-layer inner face and a second portion of the high-spring-index coiled fibers and/or yarns are on or inside the second-layer inner face, such that the high-spring-index coiled fibers and/or yarns are incorporated as artificial muscles on or between the first layer and the second layer; and(c) the artificial muscles are either (i) homochiral to increase the insulation of the two-layer textile when the ambient temperature gets warmer than a desired temperature or (ii) heterochiral to increase the insulation when the ambient temperature gets colder than the desired temperature.

23. A method comprising: (a) selecting a first plurality of first two-layer textiles and a second plurality of second two-layer textiles, wherein (i) each first two-layer textile in the first plurality of two-layer textiles is made by the method of claim 21;(ii) each second two-layer textile in the second plurality of two-layer textiles is made by the method of claim 22;(b) fabricating an assembly by incorporating the first plurality of two-layer textiles and the second plurality of two-layer textiles into the assembly, wherein (i) one of the first plurality of two-layer textiles of the assembly and the second plurality of two-layer textiles of the assembly increases insulation of the assembly when ambient temperature gets colder than a desired lower temperature, and(i) the other of the first plurality of two-layer textiles of the assembly and second plurality of two-layer textiles of the assembly increases insulation of the assembly when ambient temperature gets warmer than a desired upper temperature.

24. The method of claim 23, wherein (i) the first plurality of two-layer textiles of the assembly increases insulation of the assembly when ambient temperature gets colder than a desired lower temperature, and(i) the second portion of plurality of two-layer textiles of the assembly increases insulation of the assembly when ambient temperature gets warmer than a desired upper temperature.