Transport, Free Volume, Thermal and Surface Property Comparison of n-Alkyl and Perfluorinated Alkyl Acrylate Modified Thiol-Ene Networks

Abstract

Optically clear perfluorinated alkyl and n-alkyl acrylate modified thiol-ene network films were prepared via a two-step approach, first by modifying multifunctional thiols with perfluorinated n-alkyl and aliphatic n-alkyl acrylates of varying lengths followed by UV curing in the presence of multifunctional enes. Properties of the two types of modifying acrylates are compared in this study. By increasing the length of both n-alkyl and perfluorinated species, free volume of the networks was shown to noticeably increase over a non-modified thiol-ene network. As a result, oxygen permeability showed large gains with the increase of length of perflurinated and n-alkyl moieties as compared to an unmodified network. Network average hole free volume was determined to increase with increased side chain length. Density decreased as a result of decreased length n-alkyl modifications but increased for perfluorinated alkyl chains. Contact angles of the two networks were also compared.