Controlled free-radical copolymerization of maleic anhydride and divinyl ether in the presence of reversible addition-fragmentation chain-transfer agents

The free-radical alternating cyclocopolymerization of maleic anhydride and divinyl ether is studied at 60–80°C in the presence of benzyl dithiobenzoate and dibenzyl trithiocarbonate as reversible addition-fragmentation chain-transfer agents. It is shown that the structure of the repeating unit of the cyclocopolymer prepared in the presence of a reversible addition-fragmentation chain-transfer agent coincides with the structure of the repeating unit of the copolymer synthesized under the conditions of conventional free-radical cyclocopolymerization. When the cyclocopolymer is used as a reversible addition-fragmentation chaintransfer agent, a successive increase in the molecular mass of the copolymer with conversion and formation of the block copolymer in the polymerization of styrene are unambiguous evidence that the copolymerization proceeds according to the pseudoliving radical mechanism.