Schwaller Duncan, Zapién-Castillo Samuel, Carvalho Alain, Combet Jérôme, Collin Dominique, Jacomine Leandro, Kékicheff Patrick, Heinrich Benoît, Lamps Jean-Philippe, Díaz-Zavala Nancy P, Mésini Philippe J
Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
Tecnológico Nacional de México-Instituto Tecnológico de Ciudad Madero, Centro de Investigación en Petroquímica. Prolongación Bahía de Aldair, Ave. de las Bahías, Parque de la Pequeña y Mediana Industria, 89600 Altamira, Mexico.
Soft Matter. 2021 Apr 28;17(16):4386-4394. doi: 10.1039/d1sm00195g.
An amide based gelator forms gels in trans-decalin. Below concentrations of 1 wt% the gels melt at temperatures varying with concentration. Above a concentration of 1 wt%, upon heating, the gel transforms into an opaque gel at an invariant temperature, and melts at higher temperature. The gel-to-gel transition is evidenced by several techniques: DSC, rheology, NMR, OM and turbidimetry. The phase diagram with the domain of the existence of both morphs was mapped by these techniques. Optical and electronic microscopy studies show that the first gel corresponds to the self-assembled nanotubes while the second gel is formed by crystalline fibers. The fibers are crystalline, as shown by the presence of Bragg peaks in the scattering curves. Both morphs correspond to a different H-bonding pattern as shown by FTIR. The first gel forms at a higher cooling rate, is metastable and transforms slowly into the second one. The second gel is stable. It forms at a low cooling rate, or by thermal annealing or aging of the first gel.
一种基于酰胺的凝胶剂在反式十氢化萘中形成凝胶。在浓度低于1 wt%时，凝胶在随浓度变化的温度下熔化。在浓度高于1 wt%时，加热后，凝胶在恒定温度下转变为不透明凝胶，并在更高温度下熔化。凝胶到凝胶的转变通过多种技术得以证明：差示扫描量热法（DSC）、流变学、核磁共振（NMR）、光学显微镜（OM）和比浊法。通过这些技术绘制了具有两种形态存在区域的相图。光学和电子显微镜研究表明，第一种凝胶对应于自组装纳米管，而第二种凝胶由结晶纤维形成。如散射曲线中布拉格峰的存在所示，这些纤维是结晶性的。傅里叶变换红外光谱（FTIR）显示，两种形态对应不同的氢键模式。第一种凝胶在较高冷却速率下形成，是亚稳态的，并会缓慢转变为第二种凝胶。第二种凝胶是稳定的。它在低冷却速率下形成，或者通过第一种凝胶的热退火或老化形成。
