Thermally Reversible Distortion Observed for Triblock Copolymers Comprising Main-Chain Liquid Crystal Polyesters Attached to Photo-Cross-Linked Cinnamate Segments at Both Ends

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• 作者：Kohei Abe ; Maito Koga ; Takumi Wakabayashi ; Sungmin Kang ; Koichi Sakajiri ; Junji Watanabe ; Masatoshi Tokita
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：48
• 期：22
• 页码：8354-8360
• 全文大小：415K
• ISSN：1520-5835

文摘

ABA triblock B5 Cin copolymers were prepared by attaching photoreactive poly(2-cinnamoyloxyethyl methacrylate) (PCEMA) segments to both ends of main-chain smectic BB-5(3-Me) polyesters. The copolymers with PCEMA volume fraction (蠁) ranging from 23% to 50% formed lamellar microdomains, and the BB-5(3-Me) block formed smectic layers parallel to the lamellae. When the B5 Cin melt was drawn into film and annealed at a liquid crystal (LC) temperature of BB-5(3-Me), the lamellae and smectic layers lay perpendicular to the longitudinal direction. The PCEMA block in the monodomain films was cross-linked by UV irradiation leading to 20% conversion. When heated, the cross-linked films with 蠁 > 37% contracted reversibly on the isotropization of the LC segment, coinciding with the reversible decrease in the lamellar spacing (D). The film elongated on the liquid crystallization by a factor which increased from 1.07 to 1.24 with decreasing 蠁.