Abstract: | Thermal and photoinitiated copolymerizations of lipamide ( 1 ), a cyclic disulfide, with styrene in the absence of initiators were investigated. The thermal copolymerization is initiated via styrene radicals producing a copolymer with sulfide and disulfide linkages in the main chain and with amide and phenyl side groups. In the photopolymerization, the diradical formed by ringopening of 1 through homolytic fission of its strained disulfide bond is the main initiating species, attacking styrene to produce a copolymer with a high content of monomeric units of 1 . |