Study on the interaction of diarylbutadiynes with free radicals: Interaction with propagating radicals of some vinyl monomers

In order to study the nature of interaction of arylbutadiynes with transien t Gee radicals, polymerization and copolymerization of some vinyl monomers such as methyl methacrylate (MMA), styrene (ST), methacrylonitrile (MAN), v inylidene chloride (VCl2), ethyl acrylate (EA) and acrylonitrile (AN), were carried out in the presence of diphenylbutadiyne (DPB), 4,4'-butadiynylene -N,N,N',N'-tetra-n-butyl-dibenzamide (BBA), and 4,4'-dibromodiphenylbutadiy ne (BPB). MMA gave all intense ESR signal at the polymerization temperature when the polymerization system became viscous, and the number of radicals increased with polymerization time. Strong signals of polyEA and polyMAN ra dicals were also observed ill the presence of DPB when the polymerization s ystem became almost solid. This is a unique case where active transient pro pagating radicals such as that of polyEA call be detected at polymerization temperature. The rates of polymerization decreased by the presence of the diacetylenes, but the molecular weights did not change with the diacetylene concentrations. UV spectroscopy revealed that there was no diacetylene uni t bonded to the obtained polymers, indicating that degradative chain transf er is trot the case. The monomer reactivity ratios for MMA-ST and MMA-AN sy stems did not vary significantly in the presence of the diacetylenes, altho ugh some difference was observed. It seems that some arylbutadiynes interac t with fi ee radicals but do not form bonds.