Synthesis of α,ω-isocyanate-telechelic poly(methyl methacrylate-co-allyl methacrylate) soft segments

Isocyanate homo telechelic poly(methyl methacrylate-co-allyl methacrylate)s were prepared and used as soft segments for thermoplastic polyurethanes. Copolymerization of allyl methacrylate and methyl methacrylate by RAFT leads to selective conversion of the methacrylate C,C double bonds, leaving the allyl groups in the polymer side chain intact. A hetero telechelic MMA/AMA copolymer (Het-PMMA/AMA, molar ratio of MMA/AMA = 10/1) with a carboxylic acid and a dithiobenzoate terminus was obtained using 4,4-azobis(4-cyano pentanoic acid) as initiator and 4-cyano pentanoic acid dithiobenzoate as chain transfer agent. In a second reaction step the dithiobenzoate terminus is converted to carboxylic acid groups by a radical exchange reaction. The carboxylic acid homo telechelic statistical copolymer (Ca-Hot-PMMA/AMA) is converted quantitatively by reaction with hexamethylene diisocyanate in order to form isocyanate homo telechelic copolymer (Is-Hot-PMMA/AMA). Last the obtained soft segments were used for polyurethane synthesis. The well-defined polymer structures are characterized by SEC, Raman, and 1H NMR spectroscopy.