Arjunan Karthi Keyan, Weng Chun-Yun, Sheng Yu-Jane, Tsao Heng-Kwong
Department of Chemical and Materials Engineering, National Central University, Taoyuan 32001, Taiwan.
Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
Langmuir. 2024 Aug 13;40(32):17081-17089. doi: 10.1021/acs.langmuir.4c02069. Epub 2024 Jul 30.
Typically, gel-like materials consist of a polymer network structure in a solvent. In this work, a gel-like material is developed in a deep eutectic solvent (DES) without the presence of a polymer network, achieved simply by adding microgels. The DES is composed of choline chloride and citric acid and remains stably in a supercooled state at room temperature, exhibiting Newtonian fluid behavior with high viscosity. When the microgel (Carbopol) concentration exceeds 2 wt %, the DES undergoes a transition from a liquid to a soft gel state, characterized as a granular eutectogel. The soft gel characteristics of eutectogels exhibit a yield stress, and their storage moduli exceed the loss moduli. The yield stress and storage moduli are observed to increase with increasing microgel concentration. In contrast, the ion conductivity decreases with increasing microgel concentration but eventually levels off. Because the eutectogel can dissolve completely in excess water, it is a physical gel-like material, attributed to the densely packed structure of microgels in the supercooled DES. Due to the absence of networks, the granular eutectogel has the capability to self-heal simply by being pushed together after being cut into two pieces.
通常，凝胶状材料由溶剂中的聚合物网络结构组成。在这项工作中，一种凝胶状材料在深共晶溶剂（DES）中被开发出来，其中不存在聚合物网络，只需添加微凝胶即可实现。DES由氯化胆碱和柠檬酸组成，在室温下以过冷状态稳定存在，表现出具有高粘度的牛顿流体行为。当微凝胶（卡波姆）浓度超过2 wt%时，DES从液态转变为软凝胶状态，其特征为颗粒状低共熔凝胶。低共熔凝胶的软凝胶特性表现出屈服应力，其储能模量超过损耗模量。观察到屈服应力和储能模量随着微凝胶浓度的增加而增加。相反，离子电导率随着微凝胶浓度的增加而降低，但最终趋于平稳。由于低共熔凝胶能完全溶解在过量的水中，它是一种物理凝胶状材料，这归因于过冷DES中微凝胶的密集堆积结构。由于不存在网络，颗粒状低共熔凝胶具有在被切成两块后简单地通过挤压在一起就能自我愈合的能力。
