Synthesis of polyurethane/vinyl polymer hybrids with unexpected mechanical properties using a macro chain transfer agent†

Polyurethane is one of the most essential polymer materials due to its wide range of applications in the forms of elastomer and foam. We here report the synthesis of customized polyurethane by hybridization with vinyl polymer using a polyurethane-based macroinitiator and successive radical polymerization. First, we performed step polymerization of a trithiocarbonate-containing diol, bis{4-[ethyl-(2-hydroxyethyl)carbamoyl]benzyl}trithiocarbonate, and isophorone diisocyanate to afford the polyurethane-based macroinitiator (PU-TTC: M_n = 27.0 × 10³; M_n/M_w = 1.71) for reversible addition–fragmentation chain-transfer (RAFT) radical polymerization of vinyl monomers. We demonstrated polymerization of styrene and methyl methacrylate mediated by PU-TTC as the macro chain transfer agent to prepare a hybrid consisting of polyurethane and poly(styrene) or poly(methyl methacrylate). Compared to the methacrylate homopolymer, differential scanning calorimetry of the polyurethane hybrid showed improved thermal properties and tensile strength tests revealed unusual elongation behavior.