Photopolymerization of bifunctional maleimides based on electron-donor/acceptor systems

Abstract

Photopolymerization of three bifunctional N-phenylmaleimide derivatives consisting of a maleimide and a methacrylate or a styryl moiety within the same molecule such as N-[4-(2-hydroxy-3-methacryloyloxypropyl)oxyphenyl]maleimide (GMAPMI), N-(4-methacryloyloxyphenyl)maleimide (MAPMI) and 4-(4-maleimidobenzoyloxy)styrene (MIBOSt) has been studied based on electron-donor/acceptor (EDA) polymerization. The photoinduced homo- and copolymerizations of GMAPMI with N-vi-nyl-2-pyrrolinone (NVP) and styrene (St) as an electron-donor:or maleic anhydride (MAh) as an electron-acceptor were carried out with or without using photoinitiators. Self-photopolymer-izations were possible even without photoinitiators but higher polymerization yields were obtained using benzoin methyl ether (BME) as a photoinitiaor. The copolymerization of GMAPMI with NVP or styrene was mainly undergone with participation of the maleimide moiety to give higher yields. The reactivity for photoinduced homopolymerization of MIBOSt is superior to GMAPMI and MAPMI since it has an electron-rich styryl moiety. All of the obtained polymers were insoluble in organic solvents due to crosslinking between different functional groups. The progress of photopolymerization was monitored by differential photocalorimetry and IR spectral analysis, and the results were compared with thermal free radical polymerizations. The mixtures of GMAPMI and commercial dimethacrylates revealed the acceptable photopolymerization tendency in the preliminary evaluation for application as photocurable dental materials.