Patent Application
20100068434
Numerous techniques of making water-repellent (superhydrophobic) surfaces, which mimic natural self cleaning surfaces such as the lotus leaf, have been demonstrated in literature. Water repellency has been accomplished by the generation of rough surfaces coated with low surface energy molecules, roughening the surface of hydrophobic materials, and creating well-ordered structures using micromachining and etching and laser ablation methods. Most of these techniques are based on physical and chemical surface modification of a single material system except for creating well-ordered structures such as aligned carbon nanotubes on various substrates. These techniques are generally limited by the amount of area that can be coated or treated at a time, and superhydrophobicity can be lost in time or as a result of mechanical rubbing of the surfaces. In addition to these techniques, nanocomposite film surfaces have been very recently considered to be an alternative platform for water-repellency. Nanocomposites are unique in the sense that otherwise incompatible material properties can be combined at the nano-scale effectively.
Although nanocomposites were initially developed for their superior mechanical, optical and transport bulk properties over conventional composites, it is now possible to fabricate superhydrophobic nanocomposite coatings as an additional benefit. The main challenge associated with superhydrophobic nanocomposite surfaces is the creation of hydrophobic surface roughness in which micro and nano-scale surface asperities are co-existent by using cost-effective single step processes. Recent studies have demonstrated that by attaching hydrophobic molecules such as fluorosilanes on the rough surface of a nanocomposite which is not water repellent, superhydrophobicity can be produced.
Superoleophobic surfaces have been achieved by only a handful of researchers to date, all of whom used either substrate limited or uneconomically scalable methods. However, superoleophobic coatings have many potential applications including fluid transfer, fluid power systems, stain resistant materials, and microfluidics. Thus, an economic superoleophobic coating with an easy application method could have a large impact in many industries. It is currently well known that the degree to which a solid surface repels a liquid mainly depends upon two factors: surface energy and surface morphology. The surface energy affects the liquid-solid surface interface by influencing the attractive forces between the liquid and solid at the molecular scale. Surface morphology alteration, on the other hand, at the micro- and/or nano-scale has been shown in numerous studies to allow for an air layer to be maintained in the space between the asperities, effectively reducing the solid-liquid surface contact area and increasing the apparent contact angle (i.e. the liquid repellency).
This distinction between surfaces that have a completely wetted contact area and surfaces that have an air layer with a fractional contact area are commonly explained by two independently developed models derived from the classical Young's equation (1): the Wenzel model given in equation (2) and the Cassie-Baxter model given in equation (3)
Where γ is the surface tension; s, l, and v refer to the solid, liquid, and vapor phases, respectively; θ is the equilibrium contact angle; θ* is the apparent contact angle on the textured surface; r is the surface roughness; and φs is the fraction of solid-liquid contact. An oil droplet that is known to completely wet a surface is termed in the “Wenzel state” and tends to leave a stain as it slides and spreads. An oil droplet with a composite interface on a textured surface is termed in the “Cassie state” and may have substantially less surface adhesion.
Only a handful of synthetic superoleophobic surfaces have been created primarily due to the extreme difficulty in creating superoleophobic surfaces because oils and alkanes (such as decane and octane) have an equilibrium contact angle less than 90° on all currently known natural and artificial surfaces. The lowest surface energy end-groups in monolayer films that are currently known are —CH2>—CH3>—CF2>—CF2H>—CF3 in decreasing order (—CF3 has the lowest surface energy). The techniques that have been used to create superoleophobic surfaces to date include silicon etching with fluorosilane functionalization and anodically oxidized aluminum with fluorinated monoalkyl phosphate functionalization. A variety of other synthetic surfaces have been created that have shown high repellency to other liquids with mildly low surface tensions such as diiodomethane, but not for liquids with low surface tensions such as oils and alkanes. Fabrication methods for these surfaces include plasma modification of benzoxazine films, electrodeposition processes, silicone nanofilament growth and fluorosilane functionalization, and plasma polymer layers deposited on micro-rough PTFE substrates. Few polymer or nanocomposite coating methods have shown reasonable oleophobicity with no superoleophobicity reported to date.
Clay-based nanocomposites have had a wide impact on composite research due to vast applications of these nanocomposites ranging from mechanically tough products to barrier materials. Properties associated with clay-based nanocomposites originate from the high aspect ratio single clay platelets provided that the clay platelets are dispersed and exfoliated effectively in the polymer matrix. In its natural form, clay particles are vermicular stacks of several individual nano-platelets. Although many different nanocomposites with well exfoliated clay nano-platelets have been developed and commercialized, superhydrophobic clay-based nanocomposites are yet to appear. Polymer-based organic/inorganic nanocomposites in which the polymer matrix is a biopolymer (natural polymer) are generally known as bionanocomposites. Biocompatibility and biodegradability open new prospects for these hybrid materials with potential applications in regenerative medicine and in environmentally friendly materials (green nanocomposites). Biomedical applications such as wound dressing composites with tunable adhesion, self-cleaning properties as well as composite adhesives and coatings for bone surgery are particularly attractive applications. Cellulose nitrate has been used in making membranes for immunological and biochemical molecule analyses. In addition, when cellulose nitrate is dissolved in ether/alcohol solvent, the solution has been used as a surgical wound dressing.
Highly water repellent bionanocomposites were originally obtained from cellulose fibers by chemically attaching hydrophobic macromolecules on their surfaces using vapor/plasma or wet chemical deposition techniques. Surface topology of cellulosic micro-fiber networks decorated with such hydrophobic nanostructures satisfies the Cassie-Baxter wetting mode for durable superhydrophobicity and hence in all of these approaches an intrinsically rough cellulose based template was used as the substrate such as cotton fabric or paper. One of the major drawbacks in using bio-based polymers for conventional applications is their relatively poor mechanical stability and high temperature performance compared to conventional polymers. However, due to their biodegradability and biocompatibility as well as recent progress in designing biomaterial composites with properties comparable to conventional polymers, bio-based polymers have been finding increasing use in many applications such as food packaging, biomedical materials and coatings, surgical implants and even computer technologies. In addition to such conventional applications, design and fabrication of functional composite materials from bio-based polymers have also been explored. For instance, fabrication of highly water repellent composite coatings from hydrophilic biopolymers containing various antibacterial additives has been demonstrated recently.
A promising approach towards designing biopolymer composites with enhanced properties is to reinforce biopolymers with conventional polymers such as epoxy resins and natural and synthetic rubber as long as the polymer miscibility is thermodynamically feasible and a favorable polymer-polymer interfacial adhesion is maintained. For instance, polylactic acid (PLA) biopolymer samples toughened using rubber prepared from trimethyl carbonate showed 250% improvement in impact properties. Moreover, various techniques are available to tune surface and bulk morphology of biopolymers, for instance, solution inversion is used in polymer membrane fabrication to cast nano- and micro-porous hydrophilic (i.e., cellulose nitrate) and hydrophobic (i.e., polyvinylidine fluoride) polymer films. Introduction of a non-solvent into well dispersed polymer solutions can induce phase separation of the polymer. The phase inverted polymer morphology can be controlled by adjusting the type and the concentration of the non-solvent.
Here, simple and cost-effective solution-based techniques of fabricating robust nanocomposite and/or biocomposite coatings are disclosed.
Compositions are provided that can include a substrate having a layer thereover, with the layer including a fluoropolymer and a nanofiller. Compositions are also provided than can include a substrate having a layer thereover, with the layer including a fluoropolymer and a clay material.
Methods of preparing a composite coating material solution are provided with the methods including preparing a first solution comprising a fluoropolymer and an acetate; preparing a second solution comprising a clay material and a nanofiller suspension; and mixing the first and second solutions to form a composite coating material solution.
Methods can also provide for: preparing a first solution comprising a fluoropolymer, a silicone material, and a clay-based metalworking fluid; preparing a second solution comprising a rosin solution and a nanofiller suspension; and mixing the first and second solutions to form a composite coating material solution.
Methods of applying a composite material layer to a substrate are also provided that can include depositing a solution onto a substrate, wherein the solution comprises a clay material and fluoropolymer.
Other methods can provide for applying a composite material layer to a substrate, with the applying comprising depositing a solution onto a substrate, wherein the solution comprises a fluoropolymer and a nanofiller.
Embodiments of the disclosure are described below with reference to the following accompanying drawings.
This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).
The coating materials and methods of the present disclosure are described with reference to
Referring first to
According to an embodiment of this aspect, the first solution can include a fluoropolymer and an acetate. The first solution can further include a carboxylic acid. According to specific implementations, the first solution can include an acrylic fluoropolymer, ethyl acetate, and formic acid, for example. In accordance with
In accordance with this embodiment of this aspect, the second solution can include a clay material and a nanofiller suspension. The second solution can also include a carboxylic acid. According to specific implementations, the second solution can include a clay-in-gum rosin, a metal oxide suspension, and trifluoroacetic acid (TFA, Sigma-Aldrich, USA). The clay material ((kaolinite) (1:1 type clay (Zeng Q H, Yu A B, Lu G Q, and Paul D R 2005, J. Nanosci. Nanotech. 5(10) 1574, hereby incorporated by reference)) filled gum rosin based thixotropic gasket sealant (clay-in-rosin composite) can be obtained from ITW Polymers, USA. Table 1 below lists the compositional details of the sealant. The sealant can be found to be dispersible in various solvents such as alcohols and ethyl acetate but not in water.
With reference to
In accordance with another embodiment of this aspect, the second solution can further include a silicone material. According to specific implementations the second solution can include a clay-in-gum rosin; a metal oxide suspension, and a quaternary silicone such as silicone quaternary compounds. This embodiment is similar to the previous, except an about 15 wt % ethanol solution of the quaternary silicone liquid replaced TFA in
Embodiments of the deposition methods can provide for the removal of solvent from one or both of the mixture that can be deposited upon the substrate to form the composition. According to an implementation, the composition can be cured to remove solvents of the mixture. The curing can be performed at room temperature or at higher temperatures including the use of pressure differential chambers such as vacuum chambers, for example. According to other implementations, the solvent of the mixture may be substantially removed during deposition through the utilization of atomizing spray techniques. The deposited composite mixture can be substantially free of solvent upon providing curing. As an example, mixtures having an sufficient content of solvent may be substantially free of this content upon providing curing. Remaining in the composition, for example, can be the fluoropolymer and nanofiller according to example embodiments. As an example, each slurry solution can be spray coated on substrates such as glass slides and cured in an oven at 80° C. for three hours.
In accordance with yet another embodiment of this aspect of the disclosure, the second solution can include an anhydride such trifluoroacetic anhydride (TFAn, Sigma-Aldrich, USA). According to specific implementations, the second solution can include a tall oil fatty acid/montmorillonite and/or a nanofiller such as carbon nanotubes (nanotubes can have an average OD of 120 nm and length of 7μ and can be obtained from Sigma-Aldrich, USA). As an example of this embodiment, Zonyl 8740 can be blended with a water-based montmorillonite (2:1 type bentonite) filled tall oil fatty acid (TOFA) or reduced rosin dispersion. The bentonite filled thixotropic TOFA paste can be obtained from Sherwin-Williams Co., USA. Common solvents such as acetone, acetates and chlorohydrocarbons cannot be used to adjust viscosity without disturbing the stability of clay dispersion. Compatibilization of the paste with Zonyl 8740 fluoropolymer suspension can be achieved by mixing equal volumes of TFAn and the paste slowly while cooling to form a mixture. Upon the mixture cooling to room temperature, a stable suspension can be formed. Heat release can be observed and can be mainly due to reaction of TFAn with water to form TFA. After stabilization of the suspension, an equal volume of Zonyl 8740 can be added and diluted with ethanol to form a final slurry. The final slurry can be spray casted upon substrates surfaces to form layers which can be cured in an oven at 80° C. for three hours. To obtain coatings with carbon nanotubes, the carbon nanotubes can be mixed with the TFAn treated dispersion before blending with Zonyl 8740. A good degree of dispersion can be achieved.
In accordance with another aspect of the disclosure and with reference to
The method can further provide for preparing a second solution that includes a rosin solution and a nanofiller suspension. According to an example aspect, the second solution can further include an anhydride and an ester. In accordance with specific implementations, the second solution can include a rosin gasket sealant, trifluoroacetic anhydride, ethyl acetate, and a metal oxide suspension.
As an example of this aspect and with reference to
In accordance with another aspect of the present disclosure and with reference to
Referring again to
In combination substrate 32 and composite material layer 38 can be considered a composition. This composition can include a fluoropolymer and a clay material. The clay material can be a clay-in-rosin material, a clay-in-gum rosin, a tall oil fatty acid, and/or thixotropic clay-based metal working fluid. The composition can further comprise a nanofiller such as one or both of a metal oxide and/or a nanotube with a specific example metal oxide being TiO2 and the nanotubes being multiwall carbon nanotubes.
Surface wettability of individual blends of TiO2 suspension and Zonyl 8740 can be studied. Blending of the two incompatible suspensions can be done by diluting the TiO2 suspension with TFA and Zonyl 8740 with Acetone/Ethyl acetate co-solvent (˜20 wt %). TFA modified TiO2 suspension can then be slowly added to the modified Zonyl 8740 solution to form a final slurry.
When the clay-in-rosin sealant is modified with a silicone quaternary compound instead of TFA (according to the method of
Coatings fabricated by utilizing an industrial cutting fluid which is a waterborne reduced rosin dispersion filled with quartz silica and bentonite clay were studied, and it can be found that TFAn shows effective viscosity reduction while maintaining dispersion stability of the fillers, clay and quartz. Part of TFAn was converted to TFA with moderate heat release due to presence of water as the main solvent in the metalworking fluid. It can also be found that due to the formation of TFA, proper dispersion of nanotubes in the suspension upon mixing was also possible. Surface morphology of the superhydrophobic surfaces obtained from procedure this formulation is presented in
Referring to
Referring to
Surface morphology of coatings fabricated by the procedure of
Referring to
In
In accordance with example implementations, a simple and one step deposition technique to fabricate superhydrophobic clay-based nanocomposite coatings filled with TiO2 and nanotubes from stable suspensions is provided. The use of hydrophobic molecules may not be necessary to treat the fabricated nanocomposite surfaces and render them superhydrophobic. The fabrication technique can be presented as three separate procedures which may differ due to the source of rosin-in-clay component used. The nanocomposites can be prepared from a blend of a waterborne perfluoro acrylic polymer emulsion (Zonyl 8740) and the aforementioned clay-in-rosin compounds. Coatings can be obtained by spray casting from multi-component solution-based slurries on glass slide substrates; however, additional substrates may be utilized. It can be found that trifluoroacetic acid (TFA), trifluoroacetic anhydride (TFAn) and silicone quaternary compounds can be effective co-solvents providing compatibilization of the water insoluble clay-in-rosin and the waterborne perfluoroacrylic polymer. Typically, clay may be in the form of layered clay (conventional form) in the nanocomposites fabricated by
Regardless of the form of clay in the nanocomposites, superhydrophobicity can be observed in all coatings. This may be attributed to the formation of hydrophobic micro- and nano-structured self-similar surface roughness which is required for superhydrophobicity. Nanocomposite coatings fabricated from in accordance with
In accordance with yet another aspect of the present disclosure, methods for applying a composite material layer to substrate are provided that includes depositing a solution onto a substrate with the solution including a fluoropolymer and a nanofiller. The solution can include a solvent and this solvent may be polar for example. The solvent can be one or more of an alcohol, ketone, and/or water. In accordance with example implementations and with reference to
The deposited composite materials and substrate can represent a composition that includes the substrate having a layer thereover, with the layer comprising a fluoropolymer and a nanofiller. The nanofiller can be a nanoscale particle configured to disperse within the layer. Example nanofillers include metal oxides such as ZnO. The nanofiller can include a metal from Groups III through VIII and IB and IIB of the periodic table of elements as well as transition metals and alkaline earth metals such as those in groups IA and IIA. The fluoropolymer can be a copolymer, it can be water-based, and/or a fluoroacrylic polymer such as perfluoroalkyl methacrylic copolymer.
Referring to FIG. 13((A) 50 μm scale bar and (B) 1 μm scale bar) as well as FIG. 14((A) 2 μm scale bar and (B) 100 μm scale bar), an SEM of the composition is provided. The composition can be prepared from a wet chemical solution composed of a nanofiller suspension such as ZnO nanoparticles (Alfa Aesar: Nanoguard), perfluoroalkyl methacrylic copolymer (PMC) (Zonyl 8740, Dupont), and acetone cosolvent (Table 4). To prepare the final hierarchically textured surfaces, the solution can be sprayed onto a substrate such as glass using a Paasche Model VL-SET double action airbrush, for example. The substrate can be coated one time from a distance of approximately 30 cm and then air dried for approximately 12 hours. Both the hydrophobicity and the oleophobicity can be tested using distilled water and hydraulic oil (Mobil DTE 11M), respectively.
Hydrophobicity and oleophobicity of the nanocomposite surfaces can be quantified by measuring the apparent contact angle (static, θ*stat; advancing, θ*adv, and receding, θ*rec) and sliding angle (i.e. roll-off or tilt angle) of 10 μL water and oil droplets on each surface using a KSV Instruments Model CAM 200 goniometer to measure the static contact angle and a Red Lake Motion Pro X high speed digital camera for capturing images of advancing and receding contact angles. By slowly rotating a pivoting platform having the substrate and composite thereon, until droplets began sliding or rolling, the droplet sliding angle can be measured utilizing a Macklanburg-Duncan SmartTool Digital Level/Inclinometer with an accuracy of one tenth of a degree. The surface morphology can be characterized using a Philips XL30 environmental scanning electron microscope (ESEM)
Co-solvents can be selected having a boiling point much lower than water. This may facilitate a substantial portion of the solvent within the spray mist evaporating before impacting the substrate. In some implementations, the solvent can evaporate mainly on the substrate and can lead to non-uniform coverage through mechanisms described as the “coffee stain” effect which can cause the water solvent contact line to pin on the substrate during evaporation, transporting nanocomposite material to the edges and forming multiple rings on the coating surface. The co-solvent acetone may be utilized and can provide a counter to the coffee stain effect and provide for more uniform curing as well as producing nanocomposite slurries that self-assemble to form hierarchical surface morphology upon curing.
The acetone cosolvent concentration of the solution can be varied, and it can be determined that using acetone instead of water as in previous literature can generate a higher degree of non-wettability (
A slow solvent evaporation rate can produce a thick and wet coating, whereas if most of the solvent evaporates before the spray mist reaches the substrate, it can produce a “dry” coating. In the case of a wet coating, the solvent evaporated mainly on the substrate and led to inhomogeneous wettability through mechanisms described by the coffee stain effect. Therefore, direct spraying of nanoparticle laden, waterborne emulsions can result in undesired inhomogeneous surface morphology due to the solvent contact line pinning on the substrate and transporting nanocomposite material to the edges during solvent evaporation. This effect may cause the formation of multiple rings on the coating surface and inhomogeneous coverage. In the case of a “dry” coating, most of the acetone cosolvent can evaporate in the distance between the spray nozzle and the substrate. This effect can allow the leftover nanocomposite material to form into a spherical shape in the air before contacting and adhering to the substrate.
By varying the nanofiller concentration such as the zinc oxide nanoparticle concentration, the amount of PMC exposure on the surface may also be controlled (
A nanofiller such as a zinc oxide nanoparticle to PMC mass fraction between 0.8 and 3.3 can be optimal for both superhydrophobicity and superoleophobicity (
Referring to
This result may reveal the ideal mass fraction for superoleophobicity. This minimum hysteresis value of 4° can indicate the ability of an oil droplet to roll freely on the surface without leaving a trailing stain, which is a rare property due to the extremely low surface tension of oil. Water droplets may show low hysteresis values at all positive zinc oxide nanoparticle mass fractions indicating superhydrophobicity for the entire range.
Referring to
The wettability results can be compared to the Cassie-Baxter model (eq. 3) for a contact area fraction θs=0.07 as well as the Wenzel model (eq. 2) for a high and low roughness factor of r=2.96 and r=1.07, respectively (
The compositions and methods can provide a robust superhydrophobic and superoleophobic nanocomposite coating that can be applied to any substrate by spray and/or brush application in much the same manner as paint is applied. The coating can be applied in large surface area applications with no more equipment than a typical spray applicator. By controlling the solvent evaporation rate in the spray system and the nanocomposite material mass fraction, the nanocomposite coatings can be transitioned from showing inhomogeneous superhydrophobic properties to both robust and homogeneous superhydrophobicity and superoleophobicity.
In accordance with embodiments of the present disclosure, cellulose-based nanocomposite coatings can be fabricated by spray casting (Internal mix atomizer, Paasche, USA) polymer dispersed modified Pickering emulsions on smooth aluminum surfaces. The polymer matrix of the composites can be prepared by compatibilizing cellulose nitrate (as collodion) with a waterborne fluoroacrylic dispersion in solution. The matrix can be a self-cleaning coating with satisfactory durability and low contact angle hysteresis. Sprayed polymer dispersed emulsions cured into porous films can demonstrate measured contact angles as high as 160°. These coatings can be supplemented with fine solid particles such as silica, carbon black and clay, and when adsorbed at liquid-liquid interfaces can act as stabilizers for emulsions, foams, and water droplets replacing surfactants. Emulsions stabilized with such surface active particles can be referred to as “Pickering emulsions” and they have been used in various food and cosmetic products as well as templates for functional composite materials. Particularly, layered silicate stabilized emulsions may be utilized for consumer and pharmaceutical products. Table 5 demonstrates example ingredients and composition of the cyclomethicone-based Pickering emulsion stabilized by layered silicate particles.
Layered silicate particle concentration of 8% wt. can be sufficient to stabilize the emulsion. The Pickering emulsion can be used to compatibilize otherwise incompatible collodion (8% wt. CN; Sigma-Aldrich, USA) and the waterborne fluoroacrylic polymer (Zonyl 8740, DuPont, USA) solutions. To obtain highly water repellent coatings, the Pickering emulsion can be modified by blending with a zinc oxide (ZnO) nanofluid (50% wt. colloidal dispersion in acetate, Alfa Aesar, USA). Before dispersing the polymers, the nanofluid modified emulsion can be sprayed onto a smooth aluminum foil by reducing its viscosity with ethanol. After annealing at 100° C. for half an hour, a hydrophobic and porous film with hierarchical surface roughness features formed as seen in
Wetting characteristics of nanocomposites fabricated from Silquat/Zonyl 8740 (Zonyl-based) dispersions in the modified emulsion can be used as a model for comparisons with cellulose nitrate and cellulose nitrate/Zonyl-based bionanocomposites. Measured static contact angles on the Zonly-based coatings were close to 165° with considerably reduced CAH as compared to cellulose nitrate-based coatings at the ideal [ZnO/emulsion] ratio as seen in
Cyclomethicone-based Pickering emulsion enabled highly water repellent and self-cleaning bionanocomposites were fabricated by spray atomization. This polymer matrix can be a blend of cellulose nitrate and waterborne fluoroacrylic polymer dispersion compatibilized with a silicone quaternary compound. The polymer blend can be dispersible in the ZnO nanofluid modified silicone oil/water Pickering emulsions. Up to 2% organic antiseptic crystals could be embedded into the bionanocomposites without effecting superhydrophobicity. In accordance with another embodiment of the disclosure, rubber reinforced biopolymer nanocomposites can be fabricated that can display sticky and/or self-cleaning superhydrophobicity. A biolubricant can be used as the non-solvent to induce phase inversion of cellulose nitrate from its diluted collodion solution upon spray casting. The biolubricant can be a blend of cosmetics grade cyclomethicone/dimethiconol oils with fruit kernel oils. Table VI shows the constituents of the biolubricant formulation. A secondary function of the biolubricant can be to introduce fatty acids mostly oleic acid) from fruit kernel oils into the nanocomposites. Oleic acid is known to self-polymerize on montmorillonite clay surfaces helping deiaminate layered structures. Three different rubber resins can be blended into the biopolymer nanocomposites i.e., hydrophobic styrene-butadiene-styrene (SBS) rubber, natural rubber (NR) and fluoroacrylic rubber latex (Zonyl 8740, DuPont, USA). Rubber compounding can enhance hydrophobicity and adhesion strength to the substrates.
A collodion cellulose nitrate solution (in equal parts) with the biolubricant (non-solvent) can be blended to form a low viscosity gel. The gel can be diluted with ethyl acetate (co-solvent) to enable atomization of the cellulose nitrate/solvent/biolubricant ternary system. Upon spray casting onto aluminum surfaces and thermosetting at 80° C., remarkably different cellulose nitrate polymer film morphology emerged as shown in
The ternary system may also be converted into rubber-toughened nanocomposites. For this purpose, surface functionalized (35-45 wt. % dimethyl dialkyl C14-018 amine) montmorillonite clay particles (Nanoclay, Nanocor Inc., USA) can be used. When tethered with fatty amine quaternary salts, montmorillonite platelets can self-aggregate to form hydrophobic surfaces showing Cassie-Baxter type wetting mode.
These montmorillonite particles can be dispersed in ethyl acetate at a concentration of 0.1 g; ml forming a stable suspension. SBS rubber cement (20 wt. % in ethyl acetate) can be dispersed in the clay suspension before blending with the ternary cellulose nitrate system. The SBS dispersed clay suspension and the ternary cellulose nitrate system can be miscible and hence, different SBS/cellulose nitrate weight ratios in the blends were prepared to analyze effect of hydrophobic rubber additive on composite superhydrophobicity and adhesion strength. Montmorillonite clay can be dispersible in hydrophobic SBS rubber. In
Replacing SBS rubber with natural rubber may also form highly water repellent coatings. Fabrication of the composites can be similar to the previous method. Vulcanites-free NR latex (30 wt. % hexane) can be further diluted with ethyl acetate to 10 wt % and dispersed in the 0.1 g/ml organoclay suspension. NR dispersed suspension was then blended into the ternary cellulose nitrate system.
Self-cleaning superhydrophobic biopolymer/rubber/organoclay coatings with strong adhesion to aluminum can be obtained from (Zonyl 8740). Equal volumes of biolubricant and Zonyl 8740 can be emulsified by mixing continuously and diluted with ethyl acetate. Ten ml cellulose nitrate collodion solution can be dispersed in the 0.1 g/ml organoclay nanofluid. Diluted biolubricant/Zonyl and biopolymer/clay dispersions can be mixed in equal volumes for spray coating. Morphology of the coatings is shown in
In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.
This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application Ser. No. 61/087,578 entitled “Composite Material Compositions and Methods”, which was filed on filed Aug. 8, 2008, as well as U.S. Provisional Patent Application Ser. No. 61/138,393 entitled “Composite Material Compositions and Methods”, which was filed Dec. 17, 2008, the entirety of each of which is incorporated by reference herein
This invention was made with Government support under Grant Number 917-SBC.MINN T5306692501 awarded by the U.S. National Science Foundation Center for Compact and Efficient Fluid Power. The Government has certain rights in the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61087578 | Aug 2008 | US | |
| 61138393 | Dec 2008 | US |
