抄録
Photopolymerizations of several systems consisting of electron-donor monomers and electron-acceptor monomers have been studied for the purpose of understanding photochemical reactions on the basis of the concept of charge- transfer, searching for new photopolymerization systems that are not subject to oxygen inhibition, and elucidating reaction pathways and mechanisms.
As an extension of our studies on photopolymerizations of N-vinylcarbazole (VCZ) in the presence of amines, photopolymerization of the VCZ -N, N-diethyl- aminoethyl methacrylate (DEAEM) system has been studied. Photoradical copolymerization proceeded by irradiation of the VCZ-DEAEM system, where VCZ and DEAEM function both as coinitiators and monomers. It was found that the polymerization is accelerated in the presence of oxygen when the monomer feed mol ratio is rich in DEAEM. A new multifunctional monomer containing an alkylamino group, N-methyl-N, N-diethanolamine dimethacrylate (MDEADM), has been prepared, and photopolymerization of the VCZ-MDEADM system has been studied. The results show that the photoradical polymerization is not strongly retarded by oxygen, producing gels without the addition of other multifunctional monomers. It is suggested that initiating free radicals in these systems are produced by the reaction of the excited triplet-state VCZ with the ground-state DEAEM or MDEADM via charge-trans er interactions. The results of other photopolymerization systems, VCZ-maleic anhydride (MAn), VCZ-fumaronitrile (FN), 2-vinyl- naphthalene (VN)-MAn and VN-FN systems are briefly described. The photochemical reactions of the VCZ-MAn and VCZ-FN systems involve cationic homopolymerization of VCZ, cyclodimerization of VCZ and 1:1 alternating radical copolymerization of VCZ with MAn or FN. The reaction course and rate depend strongly on the basicity and polarity of solvents.
