beta-Methyl-alpha-methylene-gamma-butyrolactone (MMBL) was synthesized and then was polymerized in an N,N-dimethylformamide (DMF) solution with 2,2-azobisisobutyronitrile (AIBN) initiation. The homopolymer of MMBL was soluble in DMF and acetonitrile. MMBL was homopolymerized without competing depolymerization from 50 to 70 degreesC. The rate of polymerization (R-p) for MMBL followed the kinetic expression R-p = [AIBN](0.54) [MMBL](1.04). The overall activation energy was calculated to be 86.9 kJ/mol, k(p)/k(t)(1/2) was equal to 0.050 (where k(p) is the rate constant for propagation and k(t) is the rate constant for termination), and the rate of initiation was 2.17 X 10(-8) mol L-1 s(-1). The free energy of activation, the activation enthalpy, and the activation entropy were 106.0, 84.1, and 0.0658 kJ mol(-1), respectively, for homopolymerization. The initiation efficiency was approximately 1. Styrene and MMBL were copolymerized in DMF solutions at 60 degreesC with AIBN as the initiator. The reactivity ratios (r(1) = 0.22 and r(2) = 0.73) for this copolymerization were calculated with the Kelen-Tudos method. The general reactivity parameter Q and the polarity parameter e for MMBL were calculated to be 1.54 and 0.55, respectively. (C) 2003 Wiley Periodicals, Inc.