Molecular Transport of Organic Esters into Copolymeric and Terpolymeric Membranes

Abstract

Solvent uptake into thin fluoropolymer membranes (FC-2179 and FLS-2650) has been measured as a function of temperature using a sorption gravimetric method. Diffusion coefficients, percent mass uptake, and apparent activation energies for the process of diffusion and permeation have been obtained. Both polymers exhibit anomalous diffusion behaviour and this is due to specific interactions between polymer chain segments and esters. Molecular migration of esters into the dense membrane materials showed a dependence on polymer morphology and/or their chemical structures. The liquid concentration profiles have been calculated at different depths of the membranes for different time intervals. A numerical mediod based on a finite difference approach was also employed to predict concentration profiles of liquids into the membrane materials.