Introduction of quaternary amines onto a film surface by graft polymerization

Quaternary amines were introduced onto a poly(ethylene terephthalate) (PET) film surface by two different methods using UV-induced graft polymerization. The first involves a two-step reaction: graft polymerization of N,N′-(dimethylamino)ethyl methacrylate (DMAEMA) onto the PET film, followed by quaternization of the tertiary N,N′-dimethylamino groups of grafted chains using alkyl bromides (RnBr). The second is direct graft polymerization of DMAEMA having pendant quaternary amines onto the PET film. The alkyl bromides used for quaternization of the monomers and graft chains include: n-propyl, n-butyl, n-octyl, n-lauryl, and n-cetyl bromide. The two-step method could quaternarize 90% of the pendant N,N′-dimethylamino groups of the graft chains when R3Br was used. The extent of quaternization decreased with the increasing carbon number of alkyl bromide. The direct one-step method gave a graft amine density of 8 nmol/cm2 when the monomer quaternized with R3Br was used for the graft polymerization in the presence of 1 X 10-3M sodium metaperiodate. The carbon number of alkyl chains in the quaternary amines estimated from XPS spectra was in good agreement with that of RnBr used for quaternization. © 1996 John Wiley & Sons, Inc.