Key Laboratory of Material Chemistry for Energy Conversion and Storage (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China.
State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Luoyu Road No. 1037, 430074, Wuhan, China.
Nat Commun. 2022 Jun 9;13(1):3227. doi: 10.1038/s41467-022-30973-6.
Stable interfaces between immiscible solvents are crucial for chemical synthesis and assembly, but interfaces between miscible solvents have been less explored. Here the authors report the spontaneous water-on-water spreading and self-assembly of polyelectrolyte membranes. An aqueous mixture solution containing poly(ethyleneimine) and poly(sodium 4-styrenesulfonate) spreads efficiently on acidic water, leading to the formation of hierarchically porous membranes. The reduced surface tension of the polyelectrolyte mixture solution drives the surface spreading, while the interfacial polyelectrolytes complexation triggered by the low pH of water mitigates water-in-water mixing. The synergy of surface tension and pH-dependent complexation represents a generic mechanism governing interfaces between miscible solvents for materials engineering, without the need for surfactants or sophisticated equipment. As a proof-of-concept, porous polyelectrolyte hybrid membranes are prepared by surface spreading, exhibiting exceptional solar thermal evaporation performance (2.8 kg/mh) under 1-sun irradiation.
不相容溶剂之间的稳定界面对于化学合成和组装至关重要，但可混溶性溶剂之间的界面研究较少。在这里，作者报告了聚电解质膜在水-水之间自发的铺展和自组装。含有聚乙烯亚胺和聚（4-苯乙烯磺酸钠）的水溶液混合物在酸性水中高效铺展，导致形成分级多孔膜。聚电解质混合物溶液的表面张力降低驱动表面铺展，而由水的低 pH 值触发的界面聚电解质络合减轻了水-水混合。表面张力和 pH 值依赖性络合的协同作用代表了一种通用机制，用于控制可混溶性溶剂之间的界面，而无需表面活性剂或复杂的设备。作为概念验证，通过表面铺展制备了多孔聚电解质杂化膜，在 1 个太阳照射下表现出优异的太阳能热蒸发性能（2.8 kg/mh）。
