Preparation of branched polystyrene by free radical emulsion polymerization in the presence of functional monomer

Abstract

Several branched polystyrenes were prepared by free radical emulsion polymerization in the presence of α-mercaptohexyl methacrylate (MHM) as the chain transfer monomers, potassium peroxodisulfate as the initiator and sodium dodecyl benzene sulfate as the emulsifier. Branched polystyrenes of high molecular weight and high branching degree were obtained. The obtained polymers were characterized by using three detection size exclusion chromatography (TD-SEC). The branched polystyrenes showed considerably higher molecular weights and higher branching degrees using this reaction system. The higher the mole ratio of MHM to monomer or the higher mole ratio of MHM to initiator, the higher were the obtained absolute weight average molecular weight and the branching degree of the obtained polystyrenes. In addition, low temperature of polymerization reaction also contributed to the high average molecular weight and the high average branching degree of branched polystyrene. The higher average molecular weight of branched polystyrene obtained in this system was accompanied by the higher average branching degree of the branched polystyrene. It was also shown that the nature of branched structures was not affected by the amount of initiator and reaction temperature of the polymer.