Effect of degree of acetylation and solvent on the chiroptical properties of lyotropic (acetyl) (ethyl) cellulose solutions

J. ‐X Guo, D. G. Gray

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

(Acetyl) (ethyl) cellulose (AEC) polymers with an ethyl degree of substitution (DS) of 2.5 and acetyl DS ranging from 0 to 0.5 dissolve readily in a wide range of organic solvents and form chiral nematic liquid crystalline phases in concentrated solution. The chiroptical properties of these liquid crystals are strongly influenced by the acetyl content and solvent. In dichloromethane, dibromomethane, chloroform, bromoform, m‐cresol, acetic acid, and aqueous phenol, the AEC lyotropic mesophases all show a handedness inversion as the acetyl DS of the polymers is increased, changing from left‐ to right‐handed supermolecular helicoidal structures. The temperature dependence of the pitch for these mesophases is also reversed from negative to positive with increasing acetyl DS in all the above solvents except aqueous phenol, in which the corresponding AEC mesophases change from positive to negative. The optical microscopic, optical diffraction, and ORD evidence provide a unique indication that the reversal of the handedness and temperature dependence for the AEC mesophases occurs at a compensated degree of acetylation, DA*. The corresponding compensated mesophases show an infinite pitch and behave optically like nematic mesophases. The value of the DA* is dependent on solvent. In dichloroacetic acid, AEC liquid crystals remain right‐handed, independent of the acetyl DS. At given concentration and temperature, the long pitch samples flow much more readily than short pitch samples. © 1994 John Wiley & Sons, Inc.

Original languageEnglish (US)
Pages (from-to)2529-2537
Number of pages9
JournalJournal of Polymer Science Part B: Polymer Physics
Volume32
Issue number15
DOIs
StatePublished - Nov 30 1994

Keywords

  • (acetyl)(ethyl) cellulose
  • acetylation
  • chiroptical properties
  • liquid crystals

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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