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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| Affiliation: | 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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