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Keywords:

  • liquid-crystalline polymer;
  • polysiloxane;
  • synthesis

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 1H-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