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Effect of a lateral substituent on the mesomorphic properties of ferroelectric side chain liquid crystalline polysiloxanes

 

作者: CHAIN-SHU HSU,   CHIA-HSUN TSAI,  

 

期刊: Liquid Crystals  (Taylor Available online 1997)
卷期: Volume 22, issue 6  

页码: 669-677

 

ISSN:0267-8292

 

年代: 1997

 

DOI:10.1080/026782997208767

 

出版商: Taylor & Francis Group

 

数据来源: Taylor

 

摘要:

The synthesis of side chain liquid crystalline polysiloxanes containing oligooxyethylene spacers and (S)-2-methylbutyl 4-\[(4-oxybiphenyl-4-yl)carbonyloxy]-3-fluorobenzoate mesogenic side groups is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements reveal liquid crystalline properties for all synthesized monomers and polymers. All three precursor olefinic monomers reveal cholesteric and smectic A phases. The olefinic monomer which contains two oligooxyethylene units in the spacer is the only one which reveals a twist grain boundary A phase and a blue phase, besides the cholesteric and smectic A phases. All three polysiloxanes present enantiotropic smectic A and chiral smectic C phases. The mesomorphic behaviours of the monomers and polymers are compared with those of the corresponding monomers and polymers without the lateral fluoro substituent. The results seem to demonstrate that incorporating a lateral fluoro substituent in the mesogenic cores of the monomers affects not only the mesophase thermal stability, but also the nature of the mesophases formed. However, incorporating a lateral fluoro substituent in the mesogenic cores of the polymers affects only the thermal stability of the mesophases formed. The lateral fluoro substituent has a more profound effect on the mesomorphic behaviour for the monomers than that for the polymers.

 

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