Zhang Wannian, Zhang Zhiqiang, Zhao Shanlin, Hong Kwon Ho, Zhang Ming-Yuan, Song Lijuan, Yu Fang, Luo Genxiang, He Yu-Peng
Key Laboratory for Functional Material, Educational Department of Liaoning Province, School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, P. R. China.
Key Laboratory of Petrochemical Catalytic Science and Technology, Liaoning Shihua University, Dandong Lu West 1, Fushun 113001, Liaoning, P. R. China.
Langmuir. 2021 Mar 9;37(9):2954-2962. doi: 10.1021/acs.langmuir.0c03625. Epub 2021 Feb 26.
Low molecular weight gelators (LMWG) have been extensively explored in many research fields due to their unique reversible gel-sol transformation. Intermolecular interactions between LMWG are known as the main driving force for self-assembly. During this self-assembly process, individually analyzing the contribution difference between various intermolecular interactions is crucial to understand the gel properties. Herein, we report 2,5-bis(hexadecylcarbamoyl)terephthalic acid () as a LMWG, which could efficiently form a stable organogel with -hexadecane, diesel, liquid paraffin, and base lubricant oil at a relatively low concentration. To investigate the contribution difference of intermolecular interactions, we first finished FT-IR spectroscopy and XRD experiments. On the basis of the -spacing, a crude simulation model was built and then subjected to molecular dynamics (MD) simulations. Then, we knocked out the energy contribution of the H-bonding interactions and π-π stacking, respectively, to evaluate the intermolecular interactions significantly influencing the stability of the gel system. MD simulations results suggest that the self-assembly of the aggregates was mainly driven by dense H-bonding interactions between carbonyl acid and amide moieties of , which is consistent with FT-IR data. Moreover, wave function analysis at a quantum level suggested these electrostatic interactions located in the middle of the molecule were surrounded by strong dispersion attraction originating from a hydrophobic environment. Furthermore, we also confirmed that 2 wt % was able to form gel lubricant with 150BS. The coefficient of friction (COF) data show that the gel lubricant has a better tribological performance than 150BS base lubricant oil. Finally, XPS was performed and offered valuable information about the lubrication mechanism during the friction.
低分子量凝胶剂（LMWG）因其独特的可逆凝胶-溶胶转变特性，已在许多研究领域得到广泛探索。LMWG分子间的相互作用被认为是自组装的主要驱动力。在这个自组装过程中，单独分析各种分子间相互作用的贡献差异对于理解凝胶性质至关重要。在此，我们报道了2,5-双（十六烷基氨基甲酰基）对苯二甲酸（ ）作为一种LMWG，它能够在相对较低的浓度下与正十六烷、柴油、液体石蜡和基础润滑油有效地形成稳定的有机凝胶。为了研究分子间相互作用的贡献差异，我们首先完成了傅里叶变换红外光谱（FT-IR）和X射线衍射（XRD）实验。基于层间距，建立了一个粗略的模拟模型，然后进行分子动力学（MD）模拟。然后，我们分别剔除了氢键相互作用和π-π堆积的能量贡献，以评估对凝胶体系稳定性有显著影响的分子间相互作用。MD模拟结果表明，聚集体的自组装主要由 的羰基酸和酰胺部分之间密集的氢键相互作用驱动，这与FT-IR数据一致。此外，量子水平的波函数分析表明，位于 分子中间的这些静电相互作用被源自疏水环境的强色散吸引力所包围。此外，我们还证实2 wt%的 能够与150BS形成凝胶润滑剂。摩擦系数（COF）数据表明，该凝胶润滑剂比150BS基础润滑油具有更好的摩擦学性能。最后，进行了X射线光电子能谱（XPS）分析，并提供了有关摩擦过程中润滑机制的有价值信息。
