Two-Step Surface Modification of Chemically Resistant Polymers: Blend Formation and Subsequent Chemistry1
Supercritical fluid (SCF) carbon dioxide processing has been studied as a new route to polymer surface modification. Three fluoropolymer substrates were studied: poly(tetrafluoroethylene) (PTFE), poly(chlorotrifluoroethylene) (PCTFE) and poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) using a two-step modification procedure. In the first step, blends or semiinterpenetrating networks were prepared by carrying out a free radical polymerization of styrene (or styrene with divinylbenzene or triallyl cyanurate) within the SCF-swollen polymer substrate. The second step involved sulfonating the polystyrene using heterogeneous (solution-solid) sulfonation conditions. Composition of the surfaces was determined by X-ray photoelectron spectroscopy, and wettability was assessed using water contact angle measurements. Depressed advancing and receding contact angles indicate increased wettability of all of the fluoropolymer samples.
Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003.
P
Rajagopalan
TJ
McCarthy