Han Jinpeng, Cai Mingyong, Lin Yi, Liu Weijian, Luo Xiao, Zhang Hongjun, Wang Kaiyang, Zhong Minlin
Laser Materials Processing Research Center, School of Materials Science and Engineering, Tsinghua University Beijing 100084 P. R. China
RSC Adv. 2018 Feb 12;8(12):6733-6744. doi: 10.1039/c7ra13496g. eCollection 2018 Feb 6.
Superhydrophobic surfaces have been intensively investigated in recent years. However, their durability remains a major challenge before superhydrophobic surfaces can be employed in practice. Although various works have focused on overcoming this bottleneck, no single surface has ever been able to achieve the comprehensive durability (including tangential abrasion durability, dynamic impact durability and adhesive durability) required by stringent industrial requirements. Within the hierarchical structures developed for superhydrophobicity in typical plants or animals by natural evolution, microstructures usually provide mechanical stability, strength and flexibility to protect functional nanostructures to enable high durability. However, this mechanism for achieving high durability is rarely studied or reported. We employed an ultrafast laser to fabricate micro/nanohierarchical structures on metal surfaces with tunable micro-cones and produced abundant nanostructures. We then systematically investigated their comprehensive mechanical durability by fully utilizing the protective effect of the microstructures on the functional nanostructures the tunable design of micro-cones. We confirm that the height and spatial period of the microstructures were crucial for the tangential abrasion durability and dynamic impact durability, respectively. We finally fabricated optimized superhydrophobic tungsten hierarchical surfaces, which could withstand 70 abrasion cycles, 28 min of solid particle impact or 500 tape peeling cycles to retain contact angles of greater than 150° and sliding angles of less than 20°, which demonstrated exceptional comprehensive durability. The comprehensive durability, in particular the dynamic impact durability and adhesive durability, are among the best published results. This research clarifies the mechanism whereby the microstructures effectively protected the functional nanostructures to achieve high durability of the superhydrophobic surfaces and is promising for improving the durability of superhydrophobic surfaces and thus for practical applications.
近年来，超疏水表面受到了广泛研究。然而，在超疏水表面能够实际应用之前，其耐久性仍然是一个主要挑战。尽管已有诸多研究致力于克服这一瓶颈，但尚无单一表面能够达到严格工业要求所需的综合耐久性（包括切向磨损耐久性、动态冲击耐久性和粘附耐久性）。在典型动植物通过自然进化形成的用于超疏水性的分级结构中，微观结构通常提供机械稳定性、强度和柔韧性，以保护功能纳米结构，从而实现高耐久性。然而，这种实现高耐久性的机制很少被研究或报道。我们使用超快激光在具有可调微锥的金属表面上制备了微/纳分级结构，并产生了丰富的纳米结构。然后，我们充分利用微观结构对功能纳米结构的保护作用以及微锥的可调设计，系统地研究了它们的综合机械耐久性。我们证实，微观结构的高度和空间周期分别对切向磨损耐久性和动态冲击耐久性至关重要。我们最终制备了优化的超疏水钨分级表面，该表面能够承受70次磨损循环、28分钟的固体颗粒冲击或500次胶带剥离循环，以保持大于150°的接触角和小于20°的滑动角，这表明其具有出色的综合耐久性。其综合耐久性，特别是动态冲击耐久性和粘附耐久性，是已发表结果中最好的之一。这项研究阐明了微观结构有效保护功能纳米结构以实现超疏水表面高耐久性的机制，有望提高超疏水表面的耐久性，从而推动其实际应用。
