Radical polymerization of 4‐methylene‐4H‐1,3‐benzodioxin‐2‐ones: Cyclic α‐substituted styrenes

Abstract

4‐Methylene‐4H‐1,3‐benzodioxin‐2‐one (MBDOON), an α‐substituted cyclic styrene derivative, was synthesized and polymerized readily with 2,2′‐azobis(isobutyronitrile) (AIBN) as an initiator in solution. The kinetics of the MBDOON homopolymerization with AIBN was investigated in N‐methyl‐2‐pyrrolidone (NMP). The rate of polymerization, Rp, can be expressed by Rp − k[AIBN]0.52[MBDOON]1.1 and the overall activation energy has been calcualted to be 75.7 kJ/mol. Monomer reactivity ratios in copolymerization of MBDOON (M2) with styrene (M1) are r1 = 0.31 and r2 = 3.20, from which Q and e values of MBDOON can be calculated as 3.0 and −0.7, respectively. Ring‐substituted MBDOON monomers such as 6‐chloro, 6‐methyl, and 7‐methoxy derivatives were synthesized and polymerized with AIBN. The 6‐substituted MBDOON's readily underwent radical polymerization while the 7‐methoxy‐MBDOON was slower to polymerize. Poly(MBDOON) is predominantly heterotactic. (rr = 35, mr = 46, and mm = 19%). The polymer releases carbon dioxide at about 200°C and is converted with some depolymerization to poly[(o‐hydroxyphenyl)acetylene]. The thermolysis temperature is very much affected by the ring substituent. The onset of carbon dioxide liberation was observed at 140°C in the case of the 7‐methoxyl derivative while the 6‐substituents had a smaller effect on the decarboxylation temperature. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc.