VINYL POLYMERIZATION INITIATED WITH THE LANTHANUM VERSATATE P-CHLOROBENZENEDIAZONIUM TETRAFLUOROBORATE SYSTEM

The system of lanthanum versatate (1) and p-chlorobenzenediazonium tet rafluoroborate (2) was found to induce effectively polymerizations of electron-accepting monomers such as methyl methacrylate (3) and di-2-e thythexyl itaconate (DEHI). The polymerization of 3 with the 1/2 syste m was investigated kinetically in acetone. The polymerization rate (R( p)) was expressed by R(p) = k[1/2]0,44 [3]0,65 at 50-degrees-C fixing the mole ratio of 1 and 2 at unity. The overall activation energy of t he polymerization was calculated to be 37,1 kJ - mol-1. The spin trapp ing result revealed that the initiator system produces p-chlorophenyl radicals. The polymerization system of DEHI was observed to involve ES R-observable propagating polymer radicals, indicating that the polymer ization initiated with the 1/2 system proceeds through radical mechani sm. During the polymerization, the ESR spectrum was changed in shape, suggesting that the propagating polymer radicals interact with some sp ecies formed by the initiation reaction. Interacting polymer radicals were also observed in the polymerizations of diethyl itaconate and N-d odecylmaleimide with the 1/2 system. The polymerization systems of MMA , styrene and butyl acrylate were also found to involve ESR-observable radicals, although it is vague whether they are propagating polymer r adicals or not.