Visible light induced radical coupling reactions for the synthesis of conventional polycondensates

We herein report a facile visible light induced synthetic method for preparing a series of conventional polycondensates, namely polyesters, polyurethanes and polyamides. In this system, bisbenzylbromide compounds possessing ester, urethane and amide groups in the inner structure were synthesized and employed as monomers. Irradiation of these monomers in the visible range using dimanganese decacarbonyl (Mn₂(CO)₁₀) as a radical generator by halide abstraction and subsequent radical coupling reactions yielded the corresponding polycondensates. Furthermore, the presence of halide groups at both ends of the resulting polymers provided the possibility of initiating subsequent atom transfer radical polymerization of styrene facilitating the preparation of polycondensate-based triblock copolymers. Monomers, polycondensates and the block copolymers were characterized by spectral, chromatographic and thermal analyses.