Intramolecular friedel‐crafts cyclization and subsequent hydrogenation of styrene‐isoprene random copolymers prepared by anionic polymerization for thermally‐resistant and optical applications |
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Authors: | Atsuhiro Nakahara Kotaro Satoh Hiromu Saito Masami Kamigaito |
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Institution: | 1. Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo‐cho, Chikusa‐ku, Nagoya 464‐8603, Japan;2. Kurashiki Research Center, Kuraray Co. Ltd, 2045‐1, Sakazu, Kurashiki, Okayama 710‐0801, Japan;3. Department of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture and Technology, Koganei‐shi, Tokyo 184‐8588, Japan |
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Abstract: | To synthesize novel thermally and optically high‐performing thermoplastics from commodity monomers, random styrene (St)‐isoprene (Ip) rubbers (r‐SIRs) prepared by anionic copolymerization were subjected to intramolecular Friedel‐Crafts cyclization and subsequent hydrogenation via a sequence of simple postpolymerization modifications. The CF3SO3H‐catalyzed Friedel‐Crafts alkylation of r‐SIR afforded cyclized r‐SIR (C‐r‐SIR) via the predominant formation of bicyclic tetrahydronaphthyl units to give thermoplastics with a high glass transition temperature (Tg ~130 °C), good mechanical properties, and good transparency. Subsequent hydrogenation of the small amount of remaining C?C double bonds in the uncyclized Ip units and cyclized Ip‐Ip units yielded hydrogenated C‐r‐SIR (HC‐r‐SIR) and increased the degradation temperature by about 15 °C (Td5 ≥ 380 °C). These HC‐r‐SIRs display good flexural moduli and strength, good transparency, and refractive indices similar to those of C‐r‐SIR. The birefringence of HC‐r‐SIR was successfully tuned by adjusting the comonomer content to obtain near‐zero birefringence high‐performance plastics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 |
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Keywords: | anionic polymerization birefringence high performance polymers mechanical properties modification optics thermal properties |
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