Surface modification of polystyrene films. depth profiling and mapping by raman microscopy

The chemical modification of polymer films was studied using Raman microscopy. The nitration of polystyrene films (PS) in a non-swelling reaction medium was compared with the nucleophilic substitution of chlorine atoms by cyano groups in poly(p-chloromethylstyrene) (PSC) films in mixtures of a good and a non-solvent for the polymer. Using Raman microscopy in the confocal mode, depth profiles of films modified in different conditions were recorded. In both reactions, conditions could be found which allowed the polymer films to be preferentially modified at the surface. The gradient of the degree of modification and the surface selectivity are functions of reaction time, temperature and solvent quality. The homogeneity of the modification reactions was compared by mapping of surface areas using Raman spectroscopy in the conventional mode.