Thermally Induced, Tension-Gradient-Driven Self-Assembly of Nanoparticle Films for Superhydrophobicity and Oil-Water Separation

Summary Self-assembly is one of the most popular ways to produce nanoparticle (NP) films, but it is still limited by expensive instruments, time-consuming processes, and poor controllability. Here we present a thermally induced, tension-gradient-driven nanoparticle self-assembly method to realize high-efficiency, cost-effective, environmentally friendly, and controllable fabrication of large-area NP films. The driving force of this self-assembly method comes from the tension gradient of the air-liquid interface and particle-liquid interface. Meniscus shape, immersion velocity, and temperature have significant effects on self-assembly. The as-prepared ultrathin NP films are closely packed, and the number of layers can be well controlled, exhibit excellent superhydrophobic/superoleophilic properties, and can separate various oil-water mixtures with high efficiency. Moreover, the method is suitable for various 2D and 3D substrates, which may enable efficient and controllable fabrication of NP films.