Synthesis and crosslinking behavior of a novel linear polymer bearing 1,2,3‐triazol and benzoxazine groups in the main chain by a step‐growth click‐coupling reaction

The click‐coupling reaction was applied to polycondensation, to synthesize a high‐molecular weight prepolymer having benzoxazine moieties in the main chain. For the polycondensation, a bifunctional N‐propargyl benzoxazine was synthesized from bisphenol A, propargylamine, and formaldehyde. The propargyl group was efficiently used for the copper(I)‐catalyzed alkyne‐azide “click” reaction with p‐xylene‐α,α′‐diazide, to give the corresponding linear polycondensate having 1,2,3‐triazole junctions. The polycondensation proceeded in N,N‐dimethylformamide (DMF) at room temperature. By this highly efficient “click‐” polycondensation reaction, the benzoxazine ring in the monomer was successfully introduced into the polymer main chain without any side reaction. The obtained polymer (=prepolymer) underwent thermal crosslinking to afford the corresponding product, which was insoluble in a wide range of organic solvents and exhibited higher thermal stability than the polymer before crosslinking.