Center for Membrane and Film Technology, Department of Chemical Science and Engineering , Kobe University , Kobe 657-8501 , Japan.
Department of Chemical Engineering , National Taiwan University , Taipei 10617 , Taiwan.
ACS Appl Mater Interfaces. 2018 Sep 12;10(36):30860-30870. doi: 10.1021/acsami.8b09687. Epub 2018 Aug 28.
Efficient treatment of difficult emulsified oil-water wastes is a global challenge. Membranes exhibiting unusual dual superlyophobicity (combined underwater superoleophobicity and underoil superhydrophobicity) are intriguing to realize high-efficiency separation of both oil-in-water and water-in-oil emulsions. For the first time, a robust polymeric membrane demonstrating dual superlyophobicity to common apolar oils was facilely fabricated via a simple one-step phase separation process using an aliphatic polyketone (PK) polymer, thanks to a conjunction of intermediate hydrophilicity and re-entrant fibril-like texture upon the prepared PK membrane. Further chemical modification to improve surface hydrophilicity slightly can enable dual superlyophobicity to both apolar and polar oils. It is found that a nonwetting composite state of oil against water or water against oil was obtainable on the membrane surfaces only when the probe liquids possess an equilibrium contact angle (θ or θ) larger than the critical re-entrant angle of the textured surfaces (73°), which can explain the existences of dual superlyophobicity and also the nonwetting to fully wetting transitions. A simple design chart was developed to map out the operational windows of material hydrophilicity and re-entrant geometry, that is, a possible zone, to help in the rational design of similar interfacial systems from various materials. Switchable filtrations of oil-in-water and water-in-oil nanoemulsions were achieved readily with both high flux and high rejection. The simplicity and scalability of the membrane preparation process and the well-elucidated underlying mechanisms illuminate the great application potential of the PK-based superwetting membranes.
高效处理难乳化油水混合物是一个全球性的挑战。具有反常双重超疏油性（水下超疏油性和油下超亲水性结合）的膜对于实现油水和油包水乳状液的高效分离非常有趣。首次通过简单的一步相分离法，使用脂肪族聚酮（PK）聚合物，制备了一种对常见非极性油具有双重超疏油性的坚固聚合物膜，这得益于在制备的 PK 膜上存在中间亲水性和再进入的纤维状纹理。进一步的化学修饰来稍微提高表面亲水性，可以使双重超疏油性扩展到非极性和极性油。研究发现，只有当探针液体具有大于纹理表面的临界再进入角（73°）的平衡接触角（θ或θ）时，膜表面才能获得油对水或水对油的不润湿复合状态，这可以解释双重超疏油性和非润湿到完全润湿转变的存在。开发了一个简单的设计图表，以规划材料亲水性和再进入几何形状的操作窗口，即可能的区域，以帮助从各种材料合理设计类似的界面系统。可以轻松实现油包水乳状液和水乳状液的可切换过滤，具有高流量和高截留率。膜制备过程的简单性和可扩展性以及阐明的潜在机制说明了基于 PK 的超润湿膜的巨大应用潜力。
