Synthesis and mesomorphic properties of side-chain cholesteric liquid-crystalline polysiloxanes

✍ Scribed by Ying-Ying Zheng; Qian-Yue Li; Bao-Yan Zhang; Li-Feng Zhang

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 297 KB
• Volume: 97
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.21869

✦ Synopsis

Abstract

A series of new side‐chain cholesteric liquid‐crystalline polysiloxanes was synthesized by grafting copolymerization. The chemical structures of the obtained monomers and polymers were confirmed by Fourier transform infrared or ^1^H‐NMR spectroscopy. The mesomorphic properties were investigated with differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of cholesteryl 4‐allyloxybenzoate on the phase behavior of the polymers was examined. The monomer 4‐(undec‐10‐en‐1‐yloxy)‐4′‐(4‐ethoxybenzoyloxy)biphenyl showed nematic and smectic (A, C, and B) phases upon cooling, and cholesteryl 4‐allyloxybenzoate revealed an enantiotropic cholesteric phase. One polymer showed a nematic schlieren texture, other polymers showed cholesteric Grandjean and oily‐streak textures, and another polymer showed a smectic fan‐shaped texture. The experimental results demonstrated that the glass‐transition temperature and clearing temperature decreased first and then increased with an increasing content of cholesteryl 4‐allyloxybenzoate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2392–2398, 2005