Thermoplastic graft copolymer elastomers with chain‐folding or bifurcated side chains

Abstract

Abstract Graft copolymers with a poly(oxytetramethylene) main chain and molecularly uniform oligourethane grafts were synthesized by substitution polycondensation of a telechelic polyether and the corresponding α,α′‐bifunctional oligourethane macromonomer. The side chains were either characterized by a built‐in constitutional unit allowing a symmetrical chain fold or by bifurcation with two equally long oligourethane branches. Differential scanning calorimetry, small‐angle X‐ray scattering and dynamic mechanical analysis proved a microphase‐separated system with semicrystalline oligourethane hard domains, and the materials were thermoplastic elastomers. These data and the comparative study of model compounds for the specially structured grafts and of poly(ether‐urethane)s with symmetrically chain‐folded segments illustrated that the morphology and properties of these polyurethane elastomers could be perfectly mimicked by a graft copolymer with bifurcated side chains.