Influence of backbone rigidity on the thermotropic behavior of side-chain liquid crystalline polymers synthesized by ring-opening metathesis polymerization

Bob R. Maughon, Marcus Weck, Bernhard Mohr, Robert H. Grubbs

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of backbone flexibility on the mesomorphic behavior of side-chain liquid crystalline polymers synthesized by ring-opening metathesis polymerization was investigated. The synthesis of norbornene and cyclobutene monomers containing a p-nitrostilbene moiety as the mesogenic group and polymerization of these monomers to produce side-chain liquid crystalline polymers with low polydispersities and defined molecular weights was accomplished. The relatively rigid poly(norbornene)s displayed enantiotropic nematic mesomorphism with glass transitions from 44 to 64 °C and isotropization temperatures between 108 and 121 °C, whereas the more flexible poly(butadiene)s showed enantiotropic smectic A mesomorphism with glass transition temperatures from 14 to 31 °C and isotropization temperatures between 74 and 111 °C. A diblock copolymer containing a 1:1 mixture of the poly-(norbornene) and poly(butadiene) also exhibited a smectic A mesophase, clearly demonstrating the dominance of the poly(butadiene) backbone. The dependence of the degree of polymerization and flexible spacer length on the phase transitions of these systems was determined, demonstrating stabilization of the mesophase by both increasing molecular weight and flexible spacer length.

Original languageEnglish (US)
Pages (from-to)257-265
Number of pages9
JournalMacromolecules
Volume30
Issue number2
DOIs
StatePublished - Jan 27 1997

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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