Synthesis and characterization of Liquid crystalline Cholesteric polysiloxane derivatives

ABSTRACT In this paper, two series of cholesteric liquid crystal polysiloxanes (PA and PB series) with selective reflection were synthesised. PA and PB series were both prepared by hydrosylation of monomer MA containing cholesterol, monomer MB containing D (+)-camphoric acid and 6-bromohexene (6-Br), besides PB series containing MC with cyano-group. The optical performance and thermal stability of PA and PB were observed, and the relationship between PB series and PA series was also studied. Tests such as POM, TGA, DSC and selective reflection showed that the polymers exhibited colourful Grandjean texture and excellent thermal stability. The Tg, Ti and the mesophase temperature for the PA series all tended to increase, and with the increase of steric hindrance of MB, the selective reflection may exhibit more difficulty. The PB series could dilute the steric hindrance of chiral monomers due to the introduction of cyano-group and the decrease content of MB, which not only guaranteed the polymer with wider mesophase temperature but also was conducive to appear the selective reflection and last longer, besides, with the temperature increased, the wavelength of the reflected light intended to blue shift compared to that of PA series with the same chiral contents. GRAPHICAL ABSTRACT

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