Kinetic and thermochemical study of the oxidative polymerization of α-substituted styrenes.

Abstract

This article reports a systematic kinetic study on the oxidative polymerization of α-substituted styrene monomers such as styrene (St), α-methylstyrene (AMS), 4-chloro α-methylstyrene (CAMS), and α-phenylstyrene (APS) in the presence of 2,2′-azobisisobutyronitrile as a free radical initiator at 100 psi oxygen pressure and 40-50 °C in toluene. The rate of oxidative polymerization follows the order: APS > CAMS > AMS > St. Theoretical calculations have been performed using density functional theory to support the order of oxidative polymerization rates. In addition, the synthesis and characterization of poly(4-chloro α-methylstyrene peroxide) (PCAMSP) is reported here for the first time. Elemental analysis and nuclear magnetic resonance spectroscopy confirm the alternating copolymer structure of PCAMSP with –O–O– bonds in the main chain. Thermal degradation studies using differential scanning calorimeter and thermogravimetric analysis reveal that PCAMSP degrades highly exothermically and the average enthalpy of degradation at various heating rates is found to be 48.7 ± 0.6 kcal/mol, which is of the same order reported for other vinyl polyperoxides.