Mesomomorphism enhancement of modified side-chain liquid-crystalline polysiloxanes by copolymerization

✍ Scribed by Qiu-Ju Sun; Bao-Yan Zhang; Ying-Gang Jia; Lu Yang

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 192 KB
• Volume: 97
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.21861

✦ Synopsis

Abstract

The liquid‐crystalline (LC) monomer 4‐allyoxybenzoyloxy‐4′‐buthylbenzoyloxy‐p‐phenyl (M~1~), whose LC phase appeared at lower temperatures, from 137 to 227°C, and the modified mesogenic monomer 4‐allyoxybenzoyloxy‐4′‐methyloxybenzoyloxy‐p‐biphenyl (M~2~), whose LC phase appeared at higher temperatures, from 185 to 312°C, were prepared. A series of side‐chain LC polysiloxanes containing M~1~ and M~2~ were prepared by graft copolymerization. Their LC properties were characterized by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction. The results show that the introduction of the modified mesogenic monomer M~2~ into the polymeric structure caused an additional increase in the clearing point (isotropic transition temperature) of the corresponding polysiloxanes, compared with unmodified polysiloxanes, but did not significantly affect the glass‐transition temperature. Moreover, the modified polysiloxanes exhibited nematic phases as the unmodified polymer did. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1196–1201, 2005