Preparation of polystyrene with long chain branches via free radical polymerization

Polystyrene with random long chain branches has been difficult to prepare. A new approach using small amounts of chain‐transferring monomers to copolymerize with styrene free radically was examined in this work. Of the several comonomers examined, vinylbenzylthiol yielded polystyrene with branched structure. But because of the high chain trnsfer constant, the branches occurred mainly in the low‐molecular‐weight end of the distribution. As a side interest, vinylbenzylthiol was found to be an effective agent for the broadening of molecular weight distribution.