标题： 溶剂同位素效应对液晶相变的影响：重水使介晶体电荷减少 显示英文标题

标题： Solvent isotopic effect on the phase transition of lyotropic chromonic liquid crystals: Heavy water makes mesogens less charged

摘要： 溶质和溶剂分子在液晶相中的相互作用决定了它们的物理化学性质，如相行为和粘弹性。 在我们的模型系统中，一种由二钠铬酸甘油酸盐（DSCG）制成的液晶相 （LCLC），带电的板状分子通过水中的非共价相互作用自组装形成伸长的聚集体（H$_{2}$O）。 这些聚集体排列以表现出液晶相：向列相和柱相。 在这里，我们报告当D$_2$O取代H$_2$O时，LCLC的相行为的同位素效应。 D$_2$O-DSCG的向列相到各向同性相转变温度高于 H$_2$O-DSCG。 X射线散射显示D$_2$O-LCLCs中聚集体间的相关长度明显更长。 相比之下，其他微观结构特性，如聚集体间距离和聚集体内相关长度，几乎保持不变。 我们的$^{23}$Na FT-NMR 测量表明，D$_2$O-DSCG 聚集体比 H$_2$O-DSCG 聚集体带有更少的电荷，且结合了更多的反离子，Na$^+$。聚集体之间的较弱静电排斥可能稳定了向列相，这种溶剂同位素效应可能普遍适用于具有静电相互作用的多种水溶液液晶相。 显示英文摘要

摘要： The interplay among solute and solvent molecules in lyotropic mesophases governs their physicochemical properties, such as phase behaviors and viscoelasticity. In our model system, a lyotropic chromonic liquid crystal (LCLC) made by disodium cromoglycate (DSCG), charged plank-like molecules self-assemble to form elongated aggregates via non-covalent attractions in water (H$_{2}$O). The aggregates align to exhibit liquid crystalline phases: nematic and columnar phases. Here, we report the isotopic effect on the phase behavior of the LCLC when D$_2$O is substituted for H$_2$O. D$_2$O-DSCG exhibits higher nematic-to-isotropic phase transition temperatures than H$_2$O-DSCG. X-ray scattering reveals considerably longer inter-aggregate correlation lengths in D$_2$O-LCLCs. In contrast, the other microstructural properties, such as inter-aggregate distances and intra-aggregate correlation lengths, remain almost the same. Our $^{23}$Na FT-NMR measurement reveals that D$_2$O-DSCG aggregates are less charged with more counter-ions, Na$^+$, bound to them than H$_2$O-DSCG aggregates. Weaker electrostatic repulsion between aggregates may stabilize the nematic phase, and this solvent isotopic effect may generally apply to diverse aqueous lyotropic mesophases with electrostatic interactions.