SYNTHESIS OF NOVEL BENZOXAZINE HAVING VINYL GROUPAND COPOLYMERIZATION WITH VINYL MONOMERS

Abstract

A novel benzoxazine having vinyl group, namely P-4va, was prepared from phenol, formaldehyde and 4-vinylaniline. The chemical structure of P-4va was confirmed by FT-IR and 1H NMR analyses. The polymerization behavior was investigated by differential scanning calorimetry (DSC). Exothermic peak of P-4va appeared at 209 ºC in the DSC measurement due to the chain polymerization of the vinyl group and the ring-opening of benzoxazine, which occurred at the same temperature range. Thermal cure of P-4va afforded PP-4va that has glass transition temperature (Tg) at 244 ºC and char yield above 48%, exhibiting that the thermal properties of PP-4va is higher than those of a typical polybenzoxazine without vinyl group. Radical polymerization of P-4va and copolymerization with styrene (St) and methyl methacrylate (MMA) were carried out using 2,2’-azobisisobutyronitrile as the initiator, affording homopolymer and copolymers bearing benzoxazine units as the pendant. Further heat treatment of the copolymers at 240 ºC afforded cured copolymers with Tg above 300 ºC and high char yield, indicating that the copolymers serve as high-molecular-weight precursors of polybenzoxazine.