Enormously Wide Range Cylinder Phase of Liquid Crystalline PEO-b-PMA(Az) Block Copolymer

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• 作者：Hideaki Komiyama ; Ryohei Sakai ; Shingo Hadano ; Sadayuki Asaoka ; Kaori Kamata ; Tomokazu Iyoda ; Motonori Komura ; Takeshi Yamada ; Hirohisa Yoshida
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：March 11, 2014
• 年：2014
• 卷：47
• 期：5
• 页码：1777-1782
• 全文大小：347K
• 年卷期：v.47,no.5(March 11, 2014)
• ISSN：1520-5835

文摘

A series of amphiphilic liquid crystalline diblock copolymers, PEO_m-b-PMA(Az)_n, consisting of hydrophilic poly(ethylene oxide) and hydrophobic poly(methacrylate) moieties with side chains containing liquid crystalline (LC) azobenzene moieties, produced highly ordered microphase-separated films with PEO cylinders aligned perpendicular to the smectic LC layer of azobenzene in the PMA(Az) matrix. In this paper, morphological phase diagrams of PEO_m-b-PMA(Az)_n diblock copolymers above and below the isotropic transition temperature of LC azobenzene (T_iso) are presented. The diagrams are based on small-angle X-ray scattering (SAXS) measurements of approximately 70 kinds of polymers with varying degrees of polymerization in each block. An asymmetric phase diagram described against the volume fraction of PEO (f_PEO) was obtained at temperatures above and below T_iso. The lamellar phase appears in the f_PEO window 0.52 鈮?f_PEO 鈮?0.78 above and below T_iso. Besides, the wide window, 0.087 鈮?f_PEO < 0.52, allows the PEO cylinder phase to form below T_iso. In particular, the PEO sphere phase, observed above T_iso, was completely eliminated through an order鈥搊rder transition (OOT) to the PEO cylinder phase in the window 0.087 鈮?f_PEO 鈮?0.23. Such a large expansion in the PEO-cylinder-phase window could be attributed to the main chain of LC PMA(Az) being shorter than that of the flexible PEO chain, and LC azobenzene forming a smectic layer in the microphase separated system.