Surface modification of polystyrene by photoinitiated introduction of cyano groups

The surface of polystyrene was modified by the introduction of CN groups. T his was achieved by irradiating the polymer with UV light (254 nm) in the p resence of gaseous cyanogen bromide (BrCN). X-ray photoelectron spectroscop y (XPS) and FTIR analysis showed that after irradiation both Br and CN grou ps were covalently bound to the polymer surface. Quantitative XPS analysis revealed that upon prolonged irradiation every second monomer unit at the s urface was modified with a CN group. It was demonstrated that photochemical techniques can be employed to attach specific functional groups onto polym er surfaces.