Crystallization Induced Structuring and Properties of CEC-P-CEC Elastomeric Multiblock Terpolymers

We report the synthesis and characterization of a new class of block copolymer based thermoplastic elastomers that microphase separate in response to block crystallization. Five relatively monodisperse CEC-P-CEC block terpolymers containing glassy poly(cyclohexyl-ethylene) (C), semi-crystalline poly(ethylene) (E) and elastomeric poly(ethylene-alt-propylene) (P) were synthesized in a heptablock architecture by anionic polymerization and catalytic hydrogenation. Microphase segregation is induced from a homogeneous state by E crystallization, resulting in a bicontinuous morphology with CEC and P sub-structures leading to a useful combination of tensile modulus, tensile strength and elastic recovery. This molecular design decouples the material processing temperature from copolymer composition and molecular weight due to a favorable combination of block-block interactions in the melt state.