Highly water vapor breathable materials are used in athletic apparel, military uniforms, medical clothing, and industrial dehydration processes. Increased water vapor permeability is targeted while retaining hydrophobicity on a breathable film's surface. Polyethylene glycol has been incorporated into various polymer systems to increase the water vapor permeation and fluorinated groups have been shown to decrease surface tension. Perfluoro n-alkyl acrylates of n = 2, 4, 6, and 8 carbons in length were used in a two stage process for the modification of thiol-ene networks to investigate the length effect on the water vapor permeability of highly crosslinked networks. Real time FTIR of the monomer mixtures showed near complete conversion of each monomer rapidly polymerized under a UV lamp. Fluoroalkyl acrylate modification of pentaerythritol tetrakis(3-mercaptopropionate) (4T) effectively increased water contact angle as the fluoroalkyl chain length was increased from a control (unmodified) to n = 8. The increase in water contact angle indicates that fluoroalkyl acrylates decrease surface energy of the thiol-ene film. Similarly, density of each film also increased with high fluorine content. Water-sorption uptake of the polymer showed increasing water-vapor permeation as it was subjected to environments of higher relative humidity. Highest permeation at 70% Relative Humidity was achieved with the n = 2 modified thiol monomer, with a permeation value of 114 (g*cm/m2*day*atm).

Perfluorinated acrylate modified thiol-ene networks for highly water vapor breathable, waterproof materials

245th National Meeting (2013)

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