Further discussion of steric effect on the radical polymerization of triallyl isocyanurate as compared with its isomer triallyl cyanurate: polymerization and copolymerization of corresponding trimethallyl compounds

Abstract

Abstract As part of our continuing studies concerned with the radical polymerization of multiallyl compounds, the polymerization behavior of triallyl isocyanurate (TAIC) was compared in detail with those of its isomer triallyl cyanurate (TAC). It was found by chance that the primary chain length of the TAIC polymer obtained was quite high compared with TAC polymerization. This is ascribed to the reduced occurrence of monomer chain transfer characteristic of the polymerization of allyl compounds due to the steric effect on transition state formation by the bulky side-chain group, providing an interesting example of reaction control in radical polymerization. In order to discuss in more detail this kind of the specific polymerization behavior of TAIC, this work deals with the polymerization and copolymerization of corresponding trimethallyl compounds including trimethallyl isocyanurate (TMAIC) and trimethallyl cyanurate (TMAC) having additional allylic hydrogens as α -methyl group in which no steric hindrance may occur for the transition state formation of monomer chain transfer reaction. TMAIC showed almost no homopolymerizability, while only slightly reduced polymerizability was observed for TMAC as compared with TAC. Specificity of TAIC polymerization was almost lost by copolymerizing about 20 mol% of TAC or TMAC.