The photoinitiated copolymerization of styrenesulfonate with methacrylate monomers in hydrotropic medium

Copolymers of styrenesulfonate (StyS) and methyl methacrylate, or hydroxyethyl methacrylate, were prepared by photoinitiated polymerization using the cationic dye Safranine. The reactions were be carried out at StyS concentrations higher than the MHC (0.10–0.15 M) where the monomer forms aggregates. The size of these aggregates depends on the amount of the methacrylic monomer present in the mixture prior to polymerization. The amount of the non-aromatic monomers incorporated in the polymers is mainly determined by the relative reactivity ratios. In the case of HEMA, the lower amount of methacrylate in the aggregates will reduce its proportion in the final polymer. The distribution of the monomers in the copolymers is random, as deduced from the behaviour of the emission spectra, especially the relation between the band corresponding to isolated phenyl rings and that of interacting aromatic systems.