Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269, United States.
ACS Appl Mater Interfaces. 2018 Jan 31;10(4):4213-4221. doi: 10.1021/acsami.7b15909. Epub 2018 Jan 19.
Superhydrophobic surfaces with tunable adhesion from lotus-leaf to rose-petal states have generated much attention for their potential applications in self-cleaning, anti-icing, oil-water separation, microdroplet transportation, and microfluidic devices. Herein we report a facile magnetic-field-manipulation strategy to fabricate dual-functional superhydrophobic textiles with asymmetric roll-down/pinned states on the two surfaces of the textile simultaneously. Upon exposure to a static magnetic field, fluoroalkylsilane-modified iron oxide (F-FeO) nanoparticles in polydimethylsiloxane (PDMS) moved along the magnetic field to construct discrepant hierarchical structures and roughnesses on the two sides of the textile. The positive surface (closer to the magnet, or P-surface) showed a water contact angle up to 165°, and the opposite surface (or O-surface) had a water contact angle of 152.5°. The P-surface where water droplets easily slid off with a sliding angle of 7.5° appeared in the "roll-down" state as Cassie mode, while the O-surface was in the "pinned" state as Wenzel mode, where water droplets firmly adhered even at vertical (90°) and inverted (180°) angles. The surface morphology and wetting mode were adjustable by varying the ratios of F-FeO nanoparticles and PDMS. By taking advantage of the asymmetric adhesion behaviors, the as-fabricated superhydrophobic textile was successfully applied in no-loss microdroplet transportation and oil-water separation. Our method is simple and cost-effective. The fabricated textile has the characteristics of superhydrophobicity, magnetic responsiveness, excellent chemical stability, adjustable surface morphology, and controllable adhesion. Our findings conceivably stand out as a new tool to fabricate functional superhydrophobic materials with asymmetric surface properties for various potential applications.
具有从荷叶到玫瑰花瓣状态可调附着力的超疏水表面因其在自清洁、抗结冰、油水分离、微液滴输送和微流控装置等方面的潜在应用而受到广泛关注。在此，我们报告了一种简便的磁场操纵策略，可同时在纺织品的两个表面上制造具有不对称滚落/固定状态的双功能超疏水纺织品。在暴露于静磁场下时，氟烷基硅烷修饰的氧化铁（F-FeO）纳米颗粒在聚二甲基硅氧烷（PDMS）中沿磁场移动，在纺织品的两侧构建出不同的分层结构和粗糙度。正表面（更靠近磁铁，或 P 面）的水接触角高达 165°，而相反的表面（或 O 面）的水接触角为 152.5°。P 面的水滴很容易滑落，滑动角为 7.5°，呈 Cassie 模式，而 O 面呈 Wenzel 模式，即使在垂直（90°）和倒置（180°）角度，水滴也能牢固附着。通过改变 F-FeO 纳米颗粒和 PDMS 的比例，可以调节表面形态和润湿模式。利用不对称的附着行为，成功地将制备的超疏水纺织品应用于无损微液滴输送和油水分离。我们的方法简单且具有成本效益。所制备的纺织品具有超疏水性、磁响应性、优异的化学稳定性、可调的表面形态和可控的附着力等特点。我们的发现可以作为一种新的工具，用于制造具有不对称表面性能的功能性超疏水材料，以满足各种潜在的应用需求。
