It is known that many plastic and glass subjects is in contact with moist air under different conditions (e.g., higher or lower temperature), micrometer-scale water (fogging) or ice droplets (frost) may form during the first few seconds of contact. In recent years, needs for improving antifogging properties of a plastic and glass surface have been ever-increasing.
Many antifogging coatings have recently been developed to mitigate fogging problems for a variety of applications such as eyeglasses, goggles, lenses, mirrors, and displaying devices in analytical and medical instruments.1-11 Most of the antifogging coatings are hydrophilic or supehydrophilic coatings, primarily due to their ability to significantly reduce light scattering by only allowing water to condensate in a thin-film-like form. Superhydrophilic coatings with water contact angles smaller than 5° demonstrate good antifogging property, but generally require complicated procedures to fabricate surface texture,7,12-15 which is the prerequisite to obtain superhydrophilicity (except superhydrophilic TiO2 coatings,5,6 which however require UV illumination). In addition, many coatings of this type may not resist frost formation.
It is therefore an object of the invention to provide compositions that possess antifogging characteristics.
It is also an object of the invention to provide an antifogging coating composition particularly applicable to a high-temperature high-humidity environment, and/or a low-temperature high-humidity environment.
It is a further object of the invention to provide an article comprising the antifogging composition, for example, mask, eye glasses, advertising box, displaying windows including freezer/fridge door, pick-up lens, and testing equipment.
As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that when a value is disclosed that “less than or equal to” the value, “greater than or equal to the value” and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value “10” is disclosed the “less than or equal to 10” as well as “greater than or equal to 10” is also disclosed. It is also understood that throughout the application, data is provided in a number of different formats, and that this data represents endpoints and starting points, and ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point 15 are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.
Throughout the description and claims of this specification the word “comprise” and other forms of the word, such as “comprising” and “comprises,” means including but not limited to, and is not intended to exclude, for example, other additives, components, integers, or steps.
The term “copolymer” as used herein generally means any polymer comprising the reaction product of two or more monomers wherein the polymer is derived from at least two monomeric species. For example, a copolymer may be derived from amino alkyl (meth)acrylate monomer and alkyl (meth)acrylate monomer.
The term “interpenetrating polymer network” or “IPN” refers to a spatial arrangement of two or more polymers, wherein the polymers are at least partially interlaced on a polymer scale, but not covalently bonded to each other. Interpenetrating polymer networks are occasionally used to improve the physical properties of the antifogging compositions. Different kinds of IPNs and the ways in which they may be made are available from a number of sources in the literature, such as, for example, in Advances in Interpenetrating Polymer Networks, Volume 4, by Frisch & Klempner, and in Interpenetrating Polymer Networks by Klempner, Sperling, & Utracki. In addition, many patents describe compositions and methods for synthesizing various types of IPNs containing various components.
The term “about” as used herein means greater or lesser than the value or range of values stated by 1/10 of the stated values, but is not intended to limit any value or range of values to only this broader definition. For instance, a molar ratio of amino alkyl (meth)acrylate to alkyl acrylate of about 70:30 means a molar ratio between 63:37 and 77:23. Each value or range of values preceded by the term “about” is also intended to encompass the embodiment of the stated absolute value or range of values.
References in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound. As used herein, a “wt. %” or “weight percent” or “percent by weight” of a component, unless specifically stated to the contrary, refers to the ratio of the weight of the component to the total weight of the composition in which the component is included, expressed as a percentage.
“Alkyl”, as used herein, refers to saturated or unsaturated aliphatic groups, including straight-chain alkyl, branched-chain alkyl, cycloalkyl, alkyl substituted cycloalkyl, and cycloalkyl substituted alkyl. Unless otherwise indicated, a straight chain or branched chain alkyl has 30 or fewer carbon atoms in its backbone (e.g., C1-C30 for straight chain, C3-C30 for branched chain), more preferably 20 or fewer carbon atoms, more preferably 12 or fewer carbon atoms, and most preferably 8 or fewer carbon atoms. In some embodiments, the chain has 1-6 carbons. Likewise, preferred cycloalkyls have from 3-10 carbon atoms in their ring structure, and more preferably have 5, 6 or 7 carbons in the ring structure. The ranges provided above are inclusive of all values between the minimum value and the maximum value.
The term “alkyl” includes both “unsubstituted alkyls” and “substituted alkyls”, the latter of which refers to alkyl moieties having one or more substituents replacing a hydrogen on one or more carbons of the hydrocarbon backbone.
Unless the number of carbons is otherwise specified, “lower alkyl” as used herein means an alkyl group, as defined above, but having from one to ten carbons, more preferably from one to six carbon atoms in its backbone structure. Preferred alkyl groups are lower alkyls.
The alkyl groups may also contain one or more heteroatoms within the carbon backbone. Examples include oxygen, nitrogen, sulfur, and combinations thereof. In certain embodiments, the alkyl group contains between one and four heteroatoms.
In general, the antifogging compositions contain an acrylic copolymer and a crosslinked polymer network derived from an alkylene oxide di(meth)acrylate polymer. The copolymer and the crosslinked polymer network form an interpenetrating polymer network. Typically, the copolymer and the crosslinked polymer network form a semi-interpenetrating polymer network.
i. Copolymer
The acrylic copolymer is typically formed from hydrophilic monomers such as amino alkyl (meth)acrylate and a more hydrophobic monomer such as alkyl (meth)acrylate. The copolymer may be a binary copolymer. Examples of suitable amino alkyl (meth)acrylate monomers include, but are not limited to, 2-(dimethylamino) ethyl (meth)acrylate, 2-(diethylamino) ethyl (meth)acrylate, 2-aminoethyl(meth)acrylate, 2-N-morpholinoethyl(meth)acrylate, and combinations thereof.
Examples of suitable alkyl (meth)acrylate monomers include, but are not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, and combinations thereof. Other suitable (meth)acrylate monomer include esters of α,β-monoethylenically unsaturated monocarboxylic and dicarboxylic acids having 3 to 6 carbon atoms with alkanols having 1 to 20 carbon atoms (e.g., esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid, or itaconic acid, with C1-C20, C1-C12, C1-C8, or C1-C4 alkanols). Exemplary (meth)acrylate monomers include, but are not limited to, methyl acrylate, methyl (meth)acrylate, ethyl acrylate, butyl acrylate, isobutyl (meth)acrylate, ethyl (meth)acrylate, glycidyl (meth)acrylate, vinyl acetate, acetoacetoxyethyl (meth)acrylate, acetoacetoxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxy (meth)acrylate, 2 (2 ethoxyethoxy)ethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, caprolactone (meth)acrylate, polypropyleneglycol mono(meth)acrylate, polyethyleneglycol (meth)acrylate, benzyl (meth)acrylate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, hydroxypropyl (meth)acrylate, methylpolyglycol (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and combinations thereof. In one embodiment, the acrylic copolymer is formed from 2-(dimethylamino) ethyl (meth)acrylate and methyl (meth)acrylate.
The molar ratio of the amino alkyl (meth)acrylate and alkyl (meth)acrylate monomers are varied to tailor the hydrophilic-hydrophobic balance of the copolymer, which would enable water to diffuse through the coating, but remains insoluble in water. Typically, the ratio of hydrophilic monomer units to hydrophobic monomer units in the copolymer ranges from about 4:1 to 1:1.5. Generally, the molar ratio of the amino alkyl (meth)acrylate and alkyl (meth)acrylate monomers in the copolymer can vary between about 2:3 to about 4:1, respectively. For example, the copolymer may comprise amino alkyl (meth)acrylate and alkyl (meth)acrylate monomers with molar ratios of 50:50, 60:40, 70:30, and 80:20, respectively. In one embodiment, the molar ratio of amino alkyl (meth)acrylate and alkyl (meth)acrylate monomers in the copolymer is about 70:30, respectively.
The copolymer may be a terpolymer. For example, the copolymer may contain a N-vinyl amide monomer in addition to the amino alkyl (meth)acrylate and/or the alkyl (meth)acrylate monomers. Both acyclic and cyclic constructs of N-vinyl amide monomer may be used. Cyclic N-vinyl amides, also known as N-vinyl lactams, may be used, either alone or in combination with acyclic N-vinyl amides. Generally, the cyclic N-vinyl amide contain from 4 to 13 total carbon atoms. Examples of cyclic vinyl amides include, but are not limited to, N-vinyl-2-pyrrolidone; N-vinyl piperidone; N-vinyl-2-caprolactam; N-vinyl-3-methyl pyrrolidone; N-vinyl-4-methyl pyrrolidone; N-vinyl-5-methyl pyrrolidone; N-vinyl-3-ethyl pyrrolidone; N-vinyl-3-butyl pyrrolidone; N-vinyl-3,3-dimethyl pyrrolidone; N-vinyl-4,5-dimethyl pyrrolidone; N-vinyl-5,5-dimethyl pyrrolidone; N-vinyl-3,3,5-trimethyl pyrrolidone; N-vinyl-5-methyl-5-ethyl pyrrolidone; N-vinyl-3,5-trimethyl-3-ethyl pyrrolidone; N-vinyl-6-methyl-2-piperidone; N-vinyl-6-ethyl-2-piperidone; N-vinyl-3,5-dimethyl-2-piperidone; N-vinyl-4,4-dimethyl-2-piperidone; N-vinyl-6-propyl-2-piperidone; N-vinyl-3-methyl-2-caprolactam; N-vinyl-4-methyl-2-caprolactam; N-vinyl-7-methyl-2-caprolactam; N-vinyl-3,5-dimethyl-2-caprolactam; N-vinyl-3,7-dimethyl-2-caprolactam; N-vinyl-4, 6-dimethyl-2-caprolactam, N-vinyl-3,5,7-trimethyl-2-caprolactam, N-vinyl-7-ethyl-2-caprolactam; N-vinyl-4-isopropyl-2-caprolactam; N-vinyl-5-isopropyl-2-caprolactam; N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-butyl-2-caprolactam; N-vinyl-4-butyl-2-caprolactam; N-vinyl-5-tert-butyl-2-caprolactam; N-vinyl-2-methyl-4-isopropyl-2-caprolactam; N-vinyl-5-isopropyl-7-methyl-2-caprolactam; and blends thereof. Other examples of suitable N-vinyl amide monomers include, but are not limited to, N-vinyl-propiolactam, N-vinyl-valerolactam, N-vinyl-formamide, N-vinyl-acetamide, N-Methyl-N-vinylacetamide, and combinations thereof. In one embodiment, the copolymer is formed from 2-(dimethylamino) ethyl (meth)acrylate, methyl (meth)acrylate, and N-vinyl-2-pyrrolidone (NVP). Acrylamide and acrylamide derivatives are also suitable monomers that can be used in the copolymer.
The molar ratio of the amino alkyl (meth)acrylate, alkyl (meth)acrylate, and N-vinyl amide monomers in the terpolymer ranges from about 1:1:1 to about 2.5:1:1.5, respectively. For example, the terpolymer may comprise amino alkyl (meth)acrylate, alkyl (meth)acrylate, and N-vinyl amide monomers with molar ratios of about 30:30:40, 40:30:30, or 50:30:20, respectively. In one embodiment, the terpolymer contains 2-(dimethylamino) ethyl (meth)acrylate, methyl (meth)acrylate, and N-vinyl-2-pyrrolidone with a molar ratio of about 50:30:20, respectively.
The molecular weight of the copolymers is not limited. In one embodiment, the molecular weight is in the range of from about 10,000 g/mol to about 500,000 g/mol. Typically, the molecular weight is in the range of from about 10,000 g/mol to about 200,000 g/mol.
a. Types of Copolymers
The copolymer may be branched or linear. Typically, the copolymer is linear. The monomers in the copolymer can be random, or alternating depending on the amino alkyl (meth)acrylate, alkyl (meth)acrylate, and N-vinyl amide monomers used to produce the copolymer. There may be a gradient or a statistical ordering of the monomer units into the copolymer.
ii. Crosslinked Polymer Network
The alkylene oxide di(meth)acrylate crosslinked polymer network prevents the copolymer from being overswollen by water, thus ensuring coating stability. Examples of suitable alkylene oxide di(meth)acrylate monomers that may be used to form the crosslinked polymer network include, but are not limited to, ethylene glycol dimethacylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, propylene glycol di(meth)acrylate, glycerol di(meth)acrylate, and combinations thereof. In one embodiment, the alkylene oxide di(meth)acrylate polymer is ethylene glycol dimethacylate.
The alkylene oxide di(meth)acrylate polymer is between about 0.1 and 2.0 wt % relative to the copolymer. Typically, the alkylene oxide di(meth)acrylate polymer is about 0.5 wt % relative to the copolymer.
iv. Interpenetrating Polymer Network
Typically, the composition contains an interpenetrating network (IPN) between the copolymer and the alkylene oxide crosslinked polymer network. A suitable interpenetrating polymer network can encompass any one or more of the different types of IPNs listed and described below:
Sequential interpenetrating polymer networks, in which monomers or prepolymers for synthesizing the copolymer or the crosslinked polymer network are polymerized in the presence of the copolymer or crosslinked polymer network. These networks may have been synthesized in the presence of monomers or prepolymers of the copolymer or crosslinked polymer network, which may have been interspersed with the copolymer or crosslinked polymer network after its formation or cross-linking;
Simultaneous interpenetrating polymer networks, in which monomers or prepolymers of two or more polymers or polymer networks are mixed together and polymerized and/or crosslinked simultaneously, such that the reactions of the two polymer networks do not substantially interfere with each other;
Grafted interpenetrating polymer networks, in which the two or more polymers or polymer networks are formed such that elements of the one polymer or polymer network are occasionally attached or covalently or ionically bonded to elements of an/the other polymer(s) or polymer network(s);
Semi-IPNs, in which one polymer is cross-linked to form a network while another polymer is not; the polymerization or crosslinking reactions of the one polymer may occur in the presence of one or more sets of other monomers, prepolymers, or polymers, or the composition may be formed by introducing the one or more sets of other monomers, prepolymers, or polymers to the one polymer or polymer network, for example, by simple mixing, by solublizing the mixture, e.g., in the presence of a removable solvent, or by swelling the other in the one;
Full, or “true,” interpenetrating polymer networks, in which two or more polymers or sets of prepolymers or monomers are crosslinked (and thus polymerized) to form two or more interpenetrating crosslinked networks made, for example, either simultaneously or sequentially, such that the reactions of the two polymer networks do not substantially interfere with each other;
Homo-IPNs, in which one set of prepolymers or polymers can be further polymerized, if necessary, and simultaneously or subsequently crosslinked with two or more different, independent crosslinking agents, which do not react with each other, in order to form two or more interpenetrating polymer networks;
Gradient interpenetrating polymer networks, in which either some aspect of the composition, frequently the functionality, the copolymer content, or the crosslink density of one or more other polymer networks gradually vary from location to location within some, or each, other interpenetrating polymer network(s), especially on a macroscopic level; and
Thermoplastic interpenetrating polymer networks, in which the crosslinks in at least one of the polymer systems involve physical crosslinks, e.g., such as very strong hydrogen-bonding or the presence of crystalline or glassy regions or phases within the network or system, instead of chemical or covalent bonds or crosslinks.
The antifogging compositions increase the scope of applications where antifogging of subject surface in contact with moist air under different conditions (e.g., higher or lower temperature), micrometer-scale water (fogging) or ice droplets (frost) would be desirable. Example of subjects which fogs following changes in environmental conditions include, but are not limited to, mask, eyeglasses, goggles, lenses, mirrors, advertising box, display windows, diagnostic test strip, pick-up lens, displaying devices in analytical and medical instruments.
Articles can be prepared by coating the antifogging coating composition onto at least a part of at least one surface of a substrate by utilizing a conventional coating method, such as, wire rod coating, roll coating, curtain coating, rotogravure coating, spray coating, dip coating, air knife coating, spin coating, slit coating, flow coating, or the like. Coating can take place in any standard coating machine known to the person skilled in the art.
In order to ensure uniform coating, it may be desirable to treat the substrate surface prior to coating by rinsing or cleaning the surface, or performing a plasma, corona discharge or flame treatment methods. For example, glass surfaces may be washed or rinsed prior to coating while polymer surfaces may be pretreated with plasma or corona discharge prior to coating.
The antifogging coating composition of the invention can be prepared by using conventional methods and the invention has no limitation on the preparation method thereof. For example, the antifogging coating composition of the invention can be prepared by co-dissolving the dimethacrylate monomer with the copolymer in a suitable solvent, for example toluene. A UV initiator, such as 2-hydroxy-4′-(2-hydroxyethoxy)-2-methyl propiophenone may then be added. The solution can then be coated on the clean substrate. The coating is then cured under UV irradiation for a period of time then dried in a vacuum oven overnight.
Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this pertains. The references disclosed are also individually and specifically incorporated by reference herein for the material contained in them that is discussed in the sentence in which the reference is relied upon.
The poly(MMA-co-DMAEMA) copolymers were synthesized by free radical solution polymerization. Methyl (meth)acrylate (MMA) and 2-(dimethylamino)ethyl (meth)acrylate (DMAEMA), with different DMAEMA contents (50, 60, 70, and 80 mol %), were first dissolved in ethanol (10 wt %) in a 250-mL flask, followed by the addition of AIBN (the initiator, 0.5 wt % with respect to the total monomer mass). The reaction solution was then purged by argon for 20 minutes, and the polymerization was carried out at 70° C. for 24 hours. After polymerization, the product was precipitated and washed in hexane to remove possible unreacted monomer. The resultant copolymer was dried at 50° C. for 48 hours in a vacuum oven. The molar content of the DMAEMA unit in the purified copolymers was determined by 1H-NMR to be 50%, 58%, 67% and 76%, respectively, which agreed with the theoretical values (50, 60, 70, and 80 mol %) quite well. Typical properties of the copolymers are listed below.
Ethylene glycol di(meth)acrylate (EGDMA, at 0.1, 0.5, 1.0 and 2 wt % relative to the copolymer) was co-dissolved with a random copolymer described in Example 1 in toluene (10 wt %), followed by the addition of a UV initiator, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methyl propiophenone (1 wt % relative to EGDMA). The final coatings were labeled as SIPN-B50, SIPN-B60, SIPN-B70, and SIPN-B80, respectively, depending on the molar content of the DMAEMA content.
Control Glass
Glass slides (1.5 cm×1.5 cm) were cleaned ultrasonically for 5 minutes, and then placed in a freshly prepared solution of concentrated H2SO4 and 30 vol % H2O2 (7/3, v/v) at 80° C. for 1 hour to remove organic contaminants and generate free hydroxyl groups on the surface. The glass slides were then rinsed with ultrapure water and ethanol, and dried with airflow.
Rf-Modified Glass
To render glass slides hydrophobic, the cleaned slide was chemically modified with 1H,1H,2H,2H-perfluorodecyl trichlorosilane via the chemical vapor deposition at 100° C. for 20 minutes in sealed vials. At the end of reaction, the treated slides were rinsed with anhydrous toluene, sonicated for 5 minutes to remove residue, and then dried in an oven at 100° C. for 30 minutes. The hydrophobic glass slide was labeled as Rf-modified glass.
Results of Treatment
The SIPN-B50, SIPN-B60, SIPN-B70, and SIPN-B80 compositions (referred to in
Various samples of the coated glass slides were first stored in a freezer at −20° C. for 30 minutes, and photographs were taken after the sample was exposed to ambient conditions for 5 seconds. The control, a hydrophilic glass, fogged severely (
To evaluate the antifogging performance more quantitatively, light transmission over the 400-700 nm range was collected on an Agilent 8453 UV-vis spectrophotometer. Prior to fogging tests, SIPN-B70 and SIPN-B60 coatings on glass exhibited light transmission as high as the control glass (approximately 92%,
After being subjected to the same frosting/fogging test as above, the light transmission was again monitored. In the case of the control glass and Rf-modified glass, the light transmission decreased to below 20% (
To optimize transmission and coating stability, the EGDMA content was varied (0.1-2 wt % against the copolymer content) in SIPN-B70 and the samples were subjected to a similar fogging test. The light transmission for the samples with high EGDMA contents (1 and 2 wt %) was significantly lower than their counterparts with lower EGDMA contents (
To reveal the origin of the antifogging/frost-resisting property of the copolymer coatings, the water contact angle (CA) change was monitored on these surfaces under ambient conditions. During the 600-s period, the water CAs all decreased (
The change in the diameter of the water contact area on the surface (
The SIPN-B70 coating was also exposed to boiling water steam. When the time of exposure was less than 5 seconds, no fogging occurred, but the surface did fog after longer periods of exposure. A possible cause for the poor antifogging behavior at high temperatures is the low critical solution temperature (LCST) of DMAEMA-based polymers. Pure PDMAEMA has a LCST of 38 to 40° C. in water [Burillo, E. Bucio, E. Arenas, G. P. Lopez, Macromol. Mater. Eng., 2007, 292, 214] so the copolymer with 70% DMAEMA was expected to have a slightly higher LCST. When the SIPN-B coating was exposed to boiling water steam, the temperature of the coating would increase to be above its LCST, making the copolymer no longer hydrophilic. As a consequence, water molecules could not diffuse into the polymer layer, leading to poor antifogging performance.
A possible antifogging mechanism for this new type of antifogging coatings is as follows. When molecular water in moist air from either a warmer or colder environment starts to condensate on the antifogging surface, the water molecules are immediately and rapidly absorbed into the hydrophilic segments of the copolymer (
Poly(DMAEMA-co-NVP-co-MMA) terpolymers were synthesized by free radical polymerization, similar to that of poly(MMA-co-DMAEMA) copolymers. A typical example is given as follows. Three monomers, DMAEMA, NVP (N-vinyl-2-pyrrolidone), and MMA with the molar percentage of 30% DMAEMA, 40% NVP, and 30% MMA were first dissolved in DMF (10 wt %) in a 250-mL flask, followed by the addition of AIBN as the initiator (0.5 wt % with respect to the total monomer mass). The reaction solution was then purged by argon for 20 minutes, and the polymerization was carried out at 70° C. for 24 hours. After polymerization, the product was precipitated and washed in cyclohexane to remove possible unreacted monomer. The resultant copolymer was dried at 50° C. for 48 hours in a vacuum oven. The final terpolymer was labeled Ter-30. Similarly, two other terpolymers were obtained with the following molar ratio: Ter-40 (40% DMAEMA, 30% NVP, and 30% MMA), and Ter-50 (50% DMAEMA, 20% NVP, and 30% MMA). The contents of the three monomer units in the terpolymers were confirmed by 1H-NMR.
Ethylene glycol di(meth)acrylate (EGDMA, at 0.5 wt % relative to the terpolymer) was co-dissolved with a terpolymer in toluene (10 wt %), followed by the addition of a UV initiator, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methyl propiophenone (1 wt % relative to EGDMA). The solution was then spin-coated on clean glass slides (1.5 cm×1.5 cm) at 800 rpm for 15 seconds. The coating was cured under UV irradiation in a UVP CL-1000 Ultraviolet Crosslinker apparatus (365 nm, 15 w) for 90 minutes, and dried in a vacuum oven overnight. The final coatings on the basis of Ter-30, Ter-40, and Ter-50 were labeled as SIPN-T30, SIPN-T40, and SIPN-T50, respectively, depending on the molar content of the DMAEMA unit. The coating SIPN-T40 demonstrated the best antifogging (against both cold moist air and hot water vapor) and frost-resisting performance.
Upon much longer-time exposure (60 s) to boiling water steam, no fogging was observed for the sample covered with the terpolymer-based coating 6), and excellent optical clarity was maintained. In the meantime, the terpolymer-based coating also maintained excellent frost-resisting property.
Number | Date | Country | |
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61942353 | Feb 2014 | US |