Liquid-crystalline characteristics of site-selectively-modified chitosan

Rout, D. K.; Pulapura, Satish; Gross, Richard A.

doi:10.1021/ma00074a023

Cited by 51 publications

(36 citation statements)

References 12 publications

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“…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.…”

Section: Introductionmentioning

confidence: 99%

Liquid‐crystalline behavior of chitosan in malic acid

Chang

Tsai

2007

J of Applied Polymer Sci

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This report describes how the degree of deacetylation and molecular weight of chitosan and the concentrations of sodium chloride and malic acid affect the formation of lyotropic chitosan liquid crystals. Chitosan samples of various degrees of deacetylation were prepared from b-chitin that was isolated from squid pens. They were degraded by ultrasonic irradiation to various molecular weights. The critical concentrations forming chitosan liquid crystals were determined with a polarized microscope. A chitosan sample with a degree of deacetylation of 67.2-83.6% formed cholesteric lyotropic liquid crystals when it was dissolved in 0.37-2.59M malic acid. The critical concentrations increased with increasing degrees of deacetylation of chitosan. They decreased with increasing molecular weights or increasing concentrations of sodium chloride and malic acid.

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Section: Introductionmentioning

confidence: 99%

Liquid‐crystalline behavior of chitosan in malic acid

Chang

Tsai

2007

J of Applied Polymer Sci

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Dong

Wang

et al. 2001

J of Applied Polymer Sci

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We prepared chitosans with various degrees of deacetylation (DDAs) by mixing completely deacetylated chitosan and acetic anhydride at room temperature without serious degradation and O-substitution. We obtained a standard curve to measure DDA by plotting the IR absorbance ratio of A(1560)/A(2880) against the known DDAs (from 1-100%) of 10 specimens. The effect of DDA on the critical concentration (C*) of chitosan/dichloroacetic acid solutions required to form mesophase was investigated by optical methods. A maximum C* value of 23 wt % appeared at a relative medium DDA (similar to 20%). The effect was explained by the disordering of chains with medium composition ratios of the copolymer of glucosamine and N-acetyl glucosamine. (C) 2002 John Wiley & Sons, Inc. J Appl Polym Sci 83: 1204-1208, 2002

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“…30, No. 3,1998 Figure 3(b) shows four order diffraction spots. This is a quick and simple method for determining the pitch of the cholesteric phase.…”

Section: Res Ul Ts and Discussionmentioning

confidence: 99%

Scattering Studies on Fingerprint Texture of Cyanoethyl Chitosan

Dong

1998

Polym J

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KEY WORDSSmall-Angle Light Scattering / Chitosan / Cyanoethyl Chitosan / Lyotropic Liquid Crystal / Fingerprint Texture / Pitch / Cholesteric Phase / Small-angle light scattering (SALS) was first introduced to polymeric research by Stein 1 in 1960. Since then, it has been widely used to investigate the submicrostructures of polymers, especially spherulites. However relatively few works have concentrated on liquid crystals using SALS. In this paper, a new method to measure the pitch of fingerprint texture of liquid crystalline phase was reported. EXPERIMENTAL MaterialO-Cyanoethyl chitosan was synthesized at this lab by mixing 0.5 g chitosan (degree of deacetylation, 78%; size of powder, 100 mesh), 20 mL acrylonitrile and I mL 5% aqueous sodium hydroxide, and stirring for 12 hat room temperature. Preparation of Liquid Crystalline BoxCyanoethyl chitosan solutions of given concentration (well above critical concentration) were prepared by mixing cyanoethyl chitosan and several solvents in vials, then sealed for 7 days before use it. A liquid crystalline box used for polarized light microscopy (PLM) and SALS observation was made by putting solution between two slide glasses.(a) RES UL TS AND DISCUSSIONChitosan (/3-1 -4-linked 2-amino-2-deoxy-o-glucopyranose structural repeat units) and its derivatives show lyotropic liquid crystalline phases when dissolved in suitable solvents. 2 -5 In this study, O-cyanoethyl chitosan exhibited lyotropic liquid crystalline behavior. Fingerprint texture can be observed when O-cyanoethyl chitosan is dissolved in trifluoroacetic acid, m-cresol, formamide, N,N-dimethyl formamide, N,N-dimethyl acetamide, and dimethyl sulfoxide, showing cholesteric phase. The fingerprint texture of O-cyanoethyl chitosan was quite regular and divided into different pieces which usually differed in direction. Big pieces were few and usually isolated. This provided the possibility for SALS to measure the pitch of a single big piece of fingerprint.The SALS H., pattern of a single big piece of fingerprint (size 60 x 120 µm) prepared from 20% trifluoroacetic acid solution is shown in Figure l(b). The whole piece was within the spot of the laser beam. It was not difficult to find the corresponding fingerprint (Figure l(a)) from a few big pieces in PLM according to the special orientation.In a single piece, the periodic repeat structure behaved as a grid. So diffraction spots appeared in the direction vertical to layer planes of fingerprints in SALS pattern. Normally only the first order diffraction can be seen. From the distance d between center and diffraction spot,

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Liquid-crystalline characteristics of site-selectively-modified chitosan

Cited by 51 publications

References 12 publications

Liquid‐crystalline behavior of chitosan in malic acid

Liquid‐crystalline behavior of chitosan in malic acid

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

Scattering Studies on Fingerprint Texture of Cyanoethyl Chitosan

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