Side-chain liquid crystal copolymers containing nonmesogenic units: Dependence of the thermal behavior upon composition

Aileen A. Craig, Corrie T. Imrie*

*Corresponding author for this work

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The reactivity ratios have been determined for a mesogenic/nonmesogenic comonomer system, namely 5-[4-(4′-methoxyphenyl)phenoxy]pentyl methacrylate/methyl methacrylate. The reactivity ratios were found to be equal and approximately unity. The copolymerization is, therefore, azeotropic and the resulting copolymers possess a random distribution sequence of the two monomers. The thermal properties of the copolymers were evaluated using differential scanning calorimetry and polarized light microscopy. Copolymers containing 0.56 or greater mol fraction of the mesogenic side-chain exhibited liquid crystallinity, specifically smectic behavior. The glass transition temperatures exhibited a negative deviation from linear behavior on varying the composition. By contrast, the clearing temperatures decrease in essentially a linear fashion as the mol fraction of the nonmesogenic unit is increased. The behavior of these copolymers is compared with a range of materials from the literature, revealing that on increasing backbone flexibility a greater mol fraction of nonmesogenic units can be incorporated into the copolymer structure while retaining liquid crystallinity. This behavior is rationalized in terms of a microphase separated smectic phase.

Original languageEnglish
Pages (from-to)421-428
Number of pages8
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume34
Issue number3
DOIs
Publication statusPublished - 1 Jan 1996

Keywords

  • Liquid crystal side-chain polymers
  • Nonmesogenic units
  • Polymethacrylate derivatives
  • Reactivity ratios

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