Macromolecular radical crossover reaction of bisulfide-containing polymer in the presence of free-radical generators

The polymer incorporating exchangeable disulfide units in the main chain was synthesized and the reorganization behavior was investigated. 2-HydroxyethyldisuLfide was employed as diol monomer for poly condensation with adipoyl chloride to afford the corresponding polyester (M_n = 28400, M_w/M_n = 1.82). The mixture of the fractionated polyesters with high and low molecular weight showed two apparent peaks in the GPC profile. They were inked in anisole, sealed, and heated at 353 K in the presence or absence of free-radical generators. In the presence of 1 mol % BPO as a free-radical generator, the peaks of the mixture gradually fused into a unimodal peak with proceeding of reaction. In contrast, no significant change in GPC profiles was observed in the absence of free-radical generators. Therefore, the phenomenon can undoubtedly be attributed to the radical crossover reaction of disulfide units between the main chains triggered by free-radical generators.