Side-Chain Liquid Crystalline Poly(meth)acrylates with Bent-Core Mesogens

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• 作者：Xiaofang Chen ; Kishore K. Tenneti ; Christopher Y. Li ; Yaowen Bai ; Xinhua Wan ; Xinghe Fan ; Qi-Feng Zhou ; Lixia Rong ; Benjamin S. Hsiao
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：February 20, 2007
• 年：2007
• 卷：40
• 期：4
• 页码：840 - 848
• 全文大小：1492K
• 年卷期：v.40,no.4(February 20, 2007)
• ISSN：1520-5835

文摘

We report the design, synthesis, and characterization of side-chain liquid crystalline (LC) poly(meth)acrylates with end-on bent-core liquid crystalline (BCLC) mesogens. Both conventional free radicalpolymerization and atom transfer radical polymerization have been used to synthesize these liquid crystallinepolymers (LCP). The resulting polymers exhibit thermotropic LC behavior. Differential scanning calorimetry,thermopolarized light microscopy, wide-angle X-ray diffraction, and small-angle X-ray scattering were used tocharacterize the LC structure of both monomers and polymers. The electro-optic (EO) measurement was carriedout by applying a triangular wave and measuring the LC EO response. SmCP (Smectic C indicates the LC moleculesare tilted with respect to the layer normal; P denotes polar ordering) phases were observed for both monomersand polymers. In LC monomers, typical antiferroelectric switching was observed. In the ground state, SmCP_A (Adenotes antiferroelectric) was observed which switched to SmCP_F (F denotes ferroelectric) upon applying anelectric field. In the corresponding LCP, a unique bilayer structure was observed, which is different from thereported BCLC bilayer SmCG (G denotes generated) phase. Most of the LCPs did not switch upon applyingelectric field while weak AF switching was observed in a low molecular weight poly{(3'-[4-(4-n-dodecyloxybenzoyloxy)benzoyloxy]-4-(12-acryloyloxydodecyloxy)benzoyloxybiphenyl} sample.