A Novel Chiral Nematic Phase in Aqueous κ-Carrageenan
A Novel Chiral Nematic Phase in Aqueous κ-Carrageenan
复制标题
水性 κ-卡拉胶中的新型手性向列相
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
L. Piculell
中科院分区：
文献类型：
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作者：
J. Borgström;P. Quist;L. Piculell
在κ-卡拉胶/NaI/水体系中发现了一种新的液晶相。通过直接混合和渗透压缩在0.1 M NaI中制备超声降解的角叉菜胶的溶液，并且在5-11%（w/w）的浓度范围内发现宏观相分离成一个各向异性的底部相和一个各向同性的顶部相。通过小角X射线散射（SAXS）、22 Na NMR和偏光显微镜研究了各向异性相的性质。通过加热至65 °C，该相可以熔融成完全各向同性的溶液，并且在室温下静置时，各向异性相再次缓慢地重新形成，表明该相处于热力学平衡。完整的（未降解）K-卡拉胶未能得到宏观相分离，但产生的浓度高于2%的双折射凝胶。
A novel liquid crystalline phase has been identified in the κ-carrageenan/NaI/water system. Solutions of ultrasonically degraded carrageenan were prepared in 0.1 M NaI both by direct mixing and by osmotic compression, and a macroscopic phase separation into one anisotropic bottom phase and one isotropic top phase was found in the concentration range 5-11% (w/w). The properties of the anisotropic phase were investigated by small-angle X-ray scattering (SAXS), 22 Na NMR, and polarized light microscopy. The phase could be melted to a completely isotropic solution by heating to 65 °C, and the anisotropic phase slowly re-formed again on standing at room temperature, indicating that the phase is in thermodynamic equilibrium. Intact (nondegraded) K-carrageenan failed to give macroscopic phase separation but yielded instead birefringent gels for concentrations higher than 2%.