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

Abstract

Cholesteric liquid crystalline phases were observed in dimethyl sulfoxide solutions of a new chitosan derivative. This chitosan derivative had a substitution pattern which approximates that of 3,6-0-(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 (X) 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 maxima, Xa, 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. The change in pitch as a function of temperature (dP/dT) was negative for all of the polymer weight fractions investigated. It was determined that the pitch-temperature relationship was dissimilar in two different temperature regions: (I) °°>|1 -TJT] > 1.25 and (II) 1.25 > |1 -TJT\ > 0, where Tc is the clearing temperature. Use of the empirical relationship (1/Xa) ~(1 -TJT)' showed that the exponent, v, within the normalized temperature region II, varies considerably (0.05-0.22) as a function of the x value, whereas, in the normalized temperature region I, v is almost independent of the x value. A comparison was carried out of the experimental pitch-temperature-concentration relationships determined herein relative to that expected on the basis of theoretical relationships proposed by Varichon, Ten Bosch, and Sixou (Liq. Cryst. 1991, 9, 701). It was found that there was very good agreement between theory and experiment for pitch-polymer concentration dependence. In contrast, the experimental pitch-temperature dependence showed poor agreement with that expected on the basis of theoretical predictions.

Liquid Crystals of Cellulosics: Fascinating Ordered Structures for the Design of Functional Material Systems

“…In Fig. 11 45. A similar inversion of the helical twist has been observed for a lyotropic series of CTC in a mixture of diethylene glycol monoethyl ether (DEME) and 2-pentanone [8,44].…”

“…Chitin consists of 2-acetamido-2-deoxy-β-D-glucose units linked together through a β(1!4) linkage, and chitosan is an N-deacetylated derivative of chitin. In contrast to the situation for cellulose derivatives, there have been only a limited number of studies of the liquid crystalline behavior of chitin or chitosan derivatives [45][46][47][48][49], except for the mesophase characterization of chitin nanocrystals (microfibrils) [3,50]. The authors' group synthesized chitosan phenylcarbamate (CtsPC) samples of varying DS (2.7-3.7) and examined the liquid crystalline characteristics in polar aprotic solvents [49].…”

Liquid‐crystalline behavior of chitosan in malic acid

“…Rout and coworkers [8][9][10] reported that N-phthalolyl chitosan, N-phthalolyl-3,6-di-O-acetyl chitosan, and N-phthalolyl-3,6-O-(butyl carbamate) chitosan had a lyotropic liquid-crystal property in dimethyl sulfoxide. The critical concentrations (C*'s; i.e., the lowest concentrations to form lyotropic liquid crystals) of these polymers were 0.25-0.27, 0.1, and 0.5%, respectively.…”

Influence of degree of deacetylation on critical concentration of chitosan/dichloroacetic acid liquid‐crystalline solution

“…6 Rout and colleagues found cholesteric solutions in N-phthalolyl chitosan and N-phthaloyl-3,6-di-Oacetyl chitosan dissolved in organic solvents. [7][8][9] Ratto et al investigated the mesophase of water/ chitosan systems with differential scanning calorimetry. 10 Dong and colleagues demonstrated the lyotropic liquid crystallinity of some chitosan derivatives and studied structure factors such as molar mass and degree of substitution on critical concentration (C*) forming the liquid-crystal phase.…”