Synthesis and Characterization of Liquid Crystalline Organosiloxanes Containing 4-Methoxyphenyl 4-(2-alkenyloxy)benzoate

Cheng-Chih Chen1 and Chih-Hung Lin1,2,*

1Center for General Education, Chang Gung University of Science and Technology, Kweishan, Taoyuan, Taiwan

2Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan, Taiwan

*Corresponding author: E-mail: chlin@mail.cgust.edu.tw

Abstract

A series of new organosiloxane liquid crystalline materials based on the 4-methoxyphenyl-4-(w-alkenyloxy)benzoate as mesogenic units have been synthesized and their mesomorphic and physical properties have been characterized. A series of new disiloxanes and trisiloxanes contain 4-methoxyphenyl 4-(w-alkenyloxy)benzoate as mesogenic these were synthesized by addition of 4-methoxyphenyl 4-(w-alkenyloxy)benzoate moiety to pentamethylhydrodisiloxane or heptamethylhydrotrisiloxane catalyzed by platinum divinyl-tetramethyldisiloxane complex. The thermal properties of this new series of thermotropic liquid-crystalline siloxanes were studied by differential scanning calorimetry and polarized optical microscope. Disiloxane series compounds were not showed any liquid crystal phase. Trisiloxanes series compounds exhibited nematic liquid crystal phase. The siloxane molecule helped to reduce the melting temperature. The thermal properties of the new siloxane series exhibited a pronounced odd-even effect with the length of alkyl segment.

Keywords

Siloxane, Odd-even, Nematic liquid crystal phase.

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