Free-radical crosslinking polymerization of neopentyl glycol dimethacrylate in the presence of lauryl mercaptan

Neopentyl glycol dimethacrylate was polymerized in bulk in the presence of lauryl mercaptan as a chain transfer agent, the primary chain length being reduced to a comparable order in allyl polymerization, and the gelation behavior was compared with diallyl terephthalate (DAT) polymerization as a typical example of multiallyl polymerizations. No Trommsdorff effect was observed, even beyond the gel point conversion, in spite of the polymerization of divinyl monomer, as were the cases of the bulk polymerization of multiallyl compounds. The variation of molecular weight distribution curves with conversion was quite similar to DAT polymerization. The deviation of actual gel point from the theoretical one was also similar, Moreover, the swelling ratio of the gel obtained just beyond the gel point was very high. Thus, no substantial difference was observed between allyl and vinyl polymerizations in the case where the primary chain lengths were adjusted to be comparable. In addition, no microgelation occurred up to the gel point. (C) 1999 Elsevier Science Ltd. All rights reserved.