Fabrication of Super Water Repellent Silver Flake/Copolymer Blend Films and Their Potential as Smart Fabrics

A facile technique is demonstrated for the fabrication of super water repellent co-polymer blend-silver composite films from fatty acid surface functionalized fine silver flakes. Initially, high concentrations of surface functionalized silver flakes were dispersed in poly(vinyl chloride-co-vinyl acetate-co-vinyl alcohol) copolymer in solution to form electrically conducting adhesives/paints (ECAs) with a bulk resistivity of similar to 3 x 10(-5) Omega cm. The solvent-borne ECAs were then blended with a water-dispersed perfluoromethacrylate copolymer (Zonyl 8740) using a simple solvent-inversion process to obtain super water-repellent colloidal copolymer blend-silver emulsions. The colloidal emulsions could be spray-deposited on a number of fibrous substrates including fabrics and paper. A particular example is demonstrated herein by spray-depositing these emulsions onto molten paraffin wax-based laminates (60 degrees C), which were partially impregnated into fabrics to fabricate highly water repellent, flexible, and thermoresponsive fabrics. A paraffin wax/polyolefin blend base film was used for the purpose. The surface topology of the superhydrophobic copolymer/silver composite films displayed fractal-like hierarchical structures ideal for self-cleaning hydrophobicity. On relatively low-absorbent permeable porous surfaces such as cellulosic films (paper) impregnated with wax/polyolefin films, self-cleaning ability of the coatings was maintained even for temperatures at which paraffin wax component of the laminated film was molten indicated by low-water roll-off angles. Hence, the composites have excellent compatibility with organic phase change materials such as paraffin wax and wax/polyolefin blends, and they can be used to fabricate nonwetting, thermoregulated, and electroactive fabrics. Antimicrobial properties of silver offer additional advantages for potential biomedical applications. POLYM. COMPOS., 32: 576-585, 2011. (C) 2011 Society of Plastics Engineers