Cholesteric Mesophases Formed by the Modified Biological Macromolecule 3,6-O-(Butyl Carbamate)-N-phthaloyl Chitosan

Cholesteric liquid crystalline phases were observed in DMSO solutions of a new chitosan derivative. This chitosan derivative had a substitution pattern which approximates that of 3,6-O-(butyl carbamate)-N-phthaloyl chitosan (BuCaPhCh). UV-visible and circular dichroic (CD) spectroscopy carried out on BuCaPhCh revealed that the cholesteric pitch is in the visible wavelength (λ) region and is left-handed for all investigated polymer weight fraction, x, values (0.50, 0.56, 0.60, and 0.70) and solution temperatures (25-88°C). The apparent absorption minima, λ a , due to selective reflection of the cholesteric phases, showed a very strong variation as x was decreased to a value near the isotropic-anisotropic solution liquid crystal transition