Synthesis and Thermal Properties of Poly(2-Chloroethyl Glycidyl Ether)-Based Side-Chain Liquid-Crystalline Polymers

Abstract

A novel series of poly(2-chloroethyl glycidyl ether)-based side-chain liquid-crystalline copolymers has been synthesized in which the mesogenic units are biphenyl 4-methoxybiphenyl, 4-methoxyazobenzene, and N-benzylidene-4-methoxyaniline, respectively (corresponding polymers are referred to as PCBH, PCMB, PCMA, and PCBM). The structures of the compounds obtained are characterized by infrared (IR) and ¹H nuclear magnetic resonance (NMR). The thermal properties were investigated using polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. The results indicate that PCMA, PCMB, and PCBM exhibit thermotropic liquid-crystalline behavior and present nematic phases with Schlieren textures. However, PCBH does not display a mesogenic phase. The decomposition temperatures of copolymers begin at 290°C.

Keywords:

• Azobenzene
• biphenyl
• liquid-crystalline polymer
• N-benzylidene-4-methoxyaniline
• poly(2-chloroethyl glycidyl ether)
• thermal properties

Acknowledgment

We are pleased to acknowledge support from Professor Cheng Sixue, Wuhan University, for her experimental assistance and a grant from the National Nature Science Foundation (No. 20474049), Specialized Research Fund for the Doctoral Program of Higher Education (No. 20040497001) of China.

Notes

^a Determined from ¹H NMR measurements.

^b Melting temperature.

^c Isotropization temperature.

^d Transition from nematic to crystalline.

^e Transition from isotropic to nematic.

^f Determined by optical microscopy.