Abstract
Cholesteric liquid crystal solutions of (acetyl)(ethyl)cellulose (AEC) in chloroform exhibit an unusual optical property, changing from a left-handed to a right-handed helicoidal structure with increasing acetyl content. The change occurs at a critical degree of acetylation, DA*, of around 0.18-0.20 for AEC solutions at room temperature. The acetyl content of AEC also strongly influences the magnitude of the cholesteric pitch and its temperature dependence. For acetyl contents below DA*, the cholesteric solutions are left-handed, with pitches which increase with acetyl content and decrease on heating. For acetyl contents above DA*, the solutions are right-handed, and the pitches decrease with increasing acetyl content and increase on heating. However, dilute solutions of all the AEC samples in chloroform show positive optical activity, independent of acetyl content.
Original language | English (US) |
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Pages (from-to) | 2086-2090 |
Number of pages | 5 |
Journal | Macromolecules |
Volume | 22 |
Issue number | 5 |
DOIs | |
State | Published - Sep 1 1989 |
Externally published | Yes |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry