RADICAL POLYMERIZATION OF ETHYL ALPHA-BENZOYLOXYMETHYLACRYLATE IN BENZENE

The polymerization of ethyl alpha-benzoyloxymethylacrylate (EBMA), an alpha-disubstituted monomer, initiated with azobisisobutyronitrile (AIBN) was studied kinetically in benzene. The polymerization rate (R(p)) at 60-degrees was expressed by R(p) = k[AIBN]0.5 [EBMA]1.6. The overall activation energy was calculated to be 53 kJ/mol. Rate constants of propagation (k(p)) and termination (k(t)) of EBMA were estimated as 990 and 2.9 x 10(6) 1/mol.sec respectively at 60-degrees, using the ESR-determined concentration of the propagating polymer radical. The large k(p) and rather low k(t) led to formation of poly(EBMA) with high molecular weight (MBARn = 1-5 x 10(5)). Thermogravimetry revealed that thermal degradation of poly(EBMA) began near 300-degrees and the residue at 500-degrees was only 2% of the initial polymer. Copolymerization of EBMA (M1) with St (M2) was also examined at 60-degrees in benzene. The following copolymerization parameters were obtained according to the Kelen-Tudos method; r1 = 0.27 +/- 0.01, r2 = 0.30 +/- 0.02 giving Q1 = 0.93 and e1 = +0.78.