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<p>The solvent composition and degree of substitution (DS) can significantly adjust the cholesteric liquid crystal behaviors of cyanoethyl cellulose (CEC) in dichloroacetic acid (DCA)/water mixture systems. CEC with high DS (2.12) groups exhibit fingerprint texture while CEC with low DS (1.76 and 1.64) groups show focal conic texture over 27.3&#xa0;wt% and the pitches of DS = 2.12 groups are in a range of approximately 3–9 μm and inversely proportional to the second to third power of CEC concentration depending on water content in solvents. The critical concentration referring to the isotropic to anisotropic phase transition is determined by the two inflection points of viscosity and refractive index. Higher water content in solvents usually lead to a larger critical concentration and a wider biphase concentration region regardless of DS. In the same solvent, a higher DS means a lower critical concentration. The layered structure is also confirmed by X-ray diffraction of liquid crystals at small angle peaks of 7°–8°. The interlayer spacing is in a range of 1.0–1.2 nm and slightly decreased with lower DS or higher water content. This work is expected to systematically reveal CEC liquid crystalline properties in DCA/water and open new horizons for expanding the application of CEC liquid crystals.</p>

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Lyotropic liquid crystal behavior of cyanoethyl cellulose in dichloroacetic acid/water systems

  • 期刊论文

  • 发表日期：

    2025年5月23日

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  • Hao Wu,
  • Zhenyu Qiao,
  • Haodong Zhang,
  • Jinping Zhou

摘要

The solvent composition and degree of substitution (DS) can significantly adjust the cholesteric liquid crystal behaviors of cyanoethyl cellulose (CEC) in dichloroacetic acid (DCA)/water mixture systems. CEC with high DS (2.12) groups exhibit fingerprint texture while CEC with low DS (1.76 and 1.64) groups show focal conic texture over 27.3 wt% and the pitches of DS = 2.12 groups are in a range of approximately 3–9 μm and inversely proportional to the second to third power of CEC concentration depending on water content in solvents. The critical concentration referring to the isotropic to anisotropic phase transition is determined by the two inflection points of viscosity and refractive index. Higher water content in solvents usually lead to a larger critical concentration and a wider biphase concentration region regardless of DS. In the same solvent, a higher DS means a lower critical concentration. The layered structure is also confirmed by X-ray diffraction of liquid crystals at small angle peaks of 7°–8°. The interlayer spacing is in a range of 1.0–1.2 nm and slightly decreased with lower DS or higher water content. This work is expected to systematically reveal CEC liquid crystalline properties in DCA/water and open new horizons for expanding the application of CEC liquid crystals.