Perfluorinated amorphous polymers exhibit an unusual combination of properties, i.e. excellent chemical resistance, low surface energy, low water adsorption, optical clarity, high gas permeability, and their applications range from transparent water repellent coatings to gas separation membranes. The aim of this study was to incorporate perfluorinated n-alkanes of different length into UV-curable thiol-ene networks thus forming amorphous films with high fluorine content. A tetra-functional thiol was modified with monofunctional fluorinated acrylates of varying chain length via thiol-Michael addition reaction and subsequently crosslinked with a trifunctional alkene. Analysis of the glass-transition temperature, and rubber elasticity plateau modulus confirmed that incorporation of perfluoroalkyl chains did not affect the network topology (the extent of cross-linking). Free volume analysis carried out using pressure-volume-temperature (PVT) and positron annihilation lifetime spectroscopy (PALS) showed a notisable increase in fractional free volume and average hole size as well as an increase in gas permeability with the increase of n-alkane chain length.

Thiol-ene networks containing perfluorinated n-alkanes: Effect of n-alkane length on free-volume and gas permeation

255th National Meeting (2018)

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