Photopolymerization of styrene with azo-containing polydimethylsiloxane as photoinitiator

Abstract

Azo-containing polydimethylsiloxane (PDMS-ACP), prepared by polycondensation reaction of bis(hydroxybutyl) polydimethylsiloxane (PDMS) with 4,4′-azobis-4-cyanopentanoyl chloride (ACPC), was used as the photoinitiator for the polymerization of styrene (St) in bulk. Polymerization of styrene with azobisisobutyronitrile (AIBN) as photoinitiator was conducted for comparision. The propagation and termination rate constants (kp and kt), and the fractions β of primary radicals entering into termination were calculated. The values of kp and kt in St/PDMS-ACP system were in agreement with that in St/AIBN system. However, the photoinitiator efficiency Φ of PDMS-ACP was found to be smaller than that of AIBN. The ratio σkt/ki of the rate constants for chain termination and chain initiation by primary radicals were determined.