Textures and disclinations in the cholesteric liquid-crystalline phase of a cyanoethyl chitosan solution

Disclinations in the fingerprint-like cholesteric texture of a natural polymer derivative, cyanoethyl chitosan, were observed and studied by both polarizing optical microscopy and scanning electron microscopy. In the latter technique, permanganic etching was developed for this cholesteric texture to increase the contrast. A special mechanism for cholesteric phase etching is suggested and discussed. Some chi, lambda, and tau disclinations and domain walls were observed. (C) 2000 John Wiley & Sons, Inc.