ELECTRON-SPIN-RESONANCE SPECTROSCOPIC PURSUIT OF NETWORK FORMATION PROCESSES IN FREE-RADICAL CROSS-LINKING POLYMERIZATIONS .1. MICROSCOPIC ENVIRONMENTAL EVALUATION AROUND COPPER(II) TETRAPHENYLPORPHYRIN SPIN-PROBE INCORPORATED INTO OR EXCLUDED FROM POLYMER NETWORK IN METHYL-METHACRYLATE ETHYLENE DIMETHACRYLATE COPOLYMERIZATION

The microheterogeneous network formation processes in the free-radical copolymerization of methyl methacrylate (MMA) with ethylene dimethacr ylate (EDMA) were pursued Electron spin resonance (ESR)-spectroscopica lly by using copper tetraphenylporphyrin (CuTPP) and copper methacrylo yloxyphenyl triphenylporphyrin (CuMAOTPP) as spin probes. Thus, CuTPP could be a useful tool to evaluate the mobility of low-molecular-weigh t molecules in the gelled system. In the MMA-EDMA copolymerization con taining CuMAOTPP, three types of CuTPP moieties existed in the polymer ization solution as immobilized in the densely crosslinked network, in corporated into the loosely crosslinked network, and unreacted monomer ; their proportion was estimated by a semi-quantitative spectral simul ation. For example, in the MMA-EDMA (70:30)-CuMAOTPP terpolymerization in a dilution of 1/10 in benzene, 30% of CuMAOTPP was immobilized at 76% conversion by the densely crosslinked network or microgel, just li ke as in a frozen state, while no restricted mobility was observed for unreacted CuMAOTPP in spite of a complete loss of fluidity of the pol ymerization solution.