ABA triblock copolymers with a ring‐opening metathesis polymerization/macromolecular chain‐transfer agent approach |
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| Authors: | Karen A Switek Kwanho Chang Frank S Bates Marc A Hillmyer |
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| Institution: | 1. Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455‐0431;2. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455‐0132Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455‐0431;3. Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455‐0431Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455‐0431 |
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| Abstract: | Block copolymers containing polystyrene and polycyclooctene were synthesized with a ring‐opening metathesis polymerization/chain‐transfer approach. Polystyrene, containing appropriately placed olefins, was prepared by anionic polymerization and served as a macromolecular chain‐transfer agent for the ring‐opening metathesis polymerization of cyclooctene. These unsaturated polymers were subsequently converted to the corresponding saturated triblock copolymers with a simple heterogeneous catalytic hydrogenation step. The molecular and morphological characterization of the block copolymers was consistent with the absence of significant branching in the central polycyclooctene and polyethylene blocks high melting temperatures (114–127 °C) and levels of crystallinity (17–42%)]. A dramatic improvement in both the long‐range order and the mechanical properties of a microphase‐separated, symmetric polystyrene–polycyclooctene–polystyrene block copolymer sample was observed after fractionation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 361–373, 2007 |
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| Keywords: | anionic polymerization block copolymers macromolecular chain‐transfer agents ROMP thermoplastic elastomers |
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