Cullari Lucas Luciano, Masiach Tom, Peretz Damari Sivan, Ligati Shani, Furó István, Regev Oren
Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
Division of Applied Physical Chemistry, Department of Chemistry, KTH Royal Institute of Technology, Stockholm SE-1044, Sweden.
ACS Appl Mater Interfaces. 2021 Feb 10;13(5):6879-6888. doi: 10.1021/acsami.0c21359. Epub 2021 Feb 1.
Dispersing graphene sheets in liquids, in particular water, could enhance the transport properties (like thermal conductivity) of the dispersion. Yet, such dispersions are difficult to achieve since graphene sheets are prone to aggregate and subsequently precipitate due to their strong van der Waals interactions. Conventional dispersion approaches, such as surface treatment of the sheets either by surfactant adsorption or by chemical modification, may prevent aggregation. Unfortunately, surfactant-assisted graphene dispersions are typically of low concentration (<0.2 wt %) with relatively small sheets (<1 μm lateral size) while chemical modification is punished by increased defect density within the sheets. We investigate here a new approach in which the concentration of dispersed graphene in water is enhanced by the addition of a fibrous clay mineral, sepiolite. As we demonstrate, the clay particles in water form a particle network within which the graphene sheets are effectively trapped. This mechanism keeps graphene sheets of (∼4 μm) dispersed at (∼1 wt %). We demonstrate the application of such dispersions as cooling liquids for thermal management solutions, where a 26% enhancement in the thermal conductivity is achieved as compared to that in a filler-free fluid.
将石墨烯片分散在液体中，尤其是水中，可以提高分散体的传输性能（如热导率）。然而，由于石墨烯片之间存在很强的范德华相互作用，容易聚集并随后沉淀，因此很难实现这种分散。传统的分散方法，如通过表面活性剂吸附或化学改性对石墨烯片进行表面处理，可能会防止聚集。不幸的是，表面活性剂辅助的石墨烯分散体通常浓度较低（<0.2 wt%），且片层相对较小（横向尺寸<1μm），而化学改性会导致片层内缺陷密度增加。我们在此研究一种新方法，即通过添加纤维状粘土矿物海泡石来提高水中分散石墨烯的浓度。正如我们所证明的，水中的粘土颗粒形成了一个颗粒网络，石墨烯片有效地被困在其中。这种机制使尺寸约为4μm的石墨烯片以约1 wt%的浓度分散。我们展示了这种分散体作为热管理解决方案的冷却液的应用，与无填料流体相比，其热导率提高了26%。
