Ion-Track Grafting of Vinylbenzyl Chloride into Poly(ethylene-co-tetrafluoroethylene) Films Using Different Media

Abstract

We investigated the ion-track grafting of vinylbenzyl chloride (VBC) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film using different grafting media for applications as anion exchange membranes for fuel cells. In an attempt to increase the grafting yield, we applied a poor solvent system as the grafting medium, i.e., a mixture of water and isopropyl alcohol (H₂O-iPrOH mixture). The optimum H₂O-iPrOH composition was identified by the kinetic parameters including the initial polymerization rate (r_p0), the radical recombination rate (γ) and the grafting efficiency (r_p0/γ). These parameters changed depending on the VBC-grafting/chain-transfer reaction competition for the radicals on ETFE and the Trommsdorff effect; the swelling of the grafting substrate gave an additional effect.