金属离子/胆酸钠超分子水凝胶特殊温度响应性的机理研究

研究了胆酸钠溶液与金属离子溶液混合自组装而成的水凝胶随温度升高而机械强度增强的独特温度响应性. 利用透射电镜(TEM)和X射线衍射(XRD)仪表征了水凝胶中聚集体的微观形貌及分子排列方式. 考察了其流变学行为、荧光性质随温度的变化. 结果表明,升温促进凝胶形成的速率, 并提高凝胶的机械强度. 随着温度的升高, 稀土离子的荧光强度显著增强. 表面张力测量表明, 胆酸钠溶液的临界胶束浓度随温度的升高而略有降低. 综合实验事实, 我们提出随温度升高导致的凝胶强度增强行为是由胆酸钠分子在高温下聚集能力增强的结果.

Investigation of the Mechanism of Temperature-Responsiveness of Metal-Cholate Supramolecular Hydrogels

Temperature-promoted hydrogel formation was investigated in a mixed solution of sodium cholate and metal ions. Transmission electron microscopy (TEM) was used to characterize the morphology of the microstructures of the hydrogels, and nanofibers were observed. The arrangement of the cholate and metal ions was proposed according to the X-ray diffraction (XRD) measurements. Rheological measurements revealed that the strength of the hydrogels increases with increasing temperature, while the fluorescence of the gels increased as well. Increasing the temperature also increased the gel formation rate. The critical micelle concentration of sodium cholate solution decreased slightly with increasing temperature. On the basis of the experimental results, we propose that the increased hydrophobicity of cholate ions with increasing temperature leads to stronger hydrogen bonding between cholate ions, which accounts for the unique heating-enhanced gelation behavior.