• Polymer(Korea)
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• v.37 no.3
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• pp.276-287
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• 2013

Two kinds of N,O-hydroxypropyl chitosans (HPCTOs) with degree of substitution (DS) and molar substitution (MS) ranging from 2.15 to 2.39 and 2.9 to 4.1, respectively, and five kinds of aliphatic acid esters of HPCTOs (HPCTOAms, m=0,2,4,7,9, the number of methylene units in aliphatic substituent) based on the HPCTOs were synthesized, and the thermotropic liquid crystalline properties of the derivatives were investigated. All the derivatives formed enantiotropic cholesteric phases whose optical pitches (${\lambda}_m$'s) increased with increasing temperature. However, the glass and clearing temperatures, the magnitude of ${\lambda}_m$ of the mesophase at the same temperature, and the temperature dependence of ${\lambda}_m$ of the investigated derivatives highly depended on MS and m. The thermotropic mesophase properties of HPCTOAms were significantly different from those reported for the aliphatic acid esters of hydroxypropyl celluloses. The results indicate that the secondary amino group in the C-2 position plays an important role in the thermal stabilization and temperature dependence of ${\lambda}_m$ of the cholesteric mesophase.