Frustrated ABC Linear Block-Random Copolymer with a Semicrystalline End Block

摘要: The solid-state structure of semicrystalline block copolymers is set either by block incompatibility or by crystallization of one or more blocks. A variety of solid-state morphologies may be observed depending on the block interaction strength, ranging from spherulitic to confined crystallization within preexisting microphase-separated domains. Linear triblock copolymers, polybutadiene-b-polyisoprene-b-poly (isoprene-r-styrene)(ABC), are synthesized via lithium-initiated anionic polymerization in cyclohexane. After polymerization of the butadiene block, triethylamine is added to facilitate the random styrene/isoprene copolymerization while also increasing the vinyl content of the polyisoprene block. Selective hydrogenation of the diene units with a Ni-Al catalyst yields a semicrystalline polyethylene endblock, with a frustrated block sequence: χ BC> χ AB>> χ AC. For a polymer with block molecular weights of 30-14-14 kg …