School of Chemistry and ‡School of Chemical and Biomolecular Engineering, The University of Sydney , Sydney, New South Wales 2006, Australia.
ACS Appl Mater Interfaces. 2017 Apr 19;9(15):13676-13684. doi: 10.1021/acsami.6b16248. Epub 2017 Mar 3.
Micropatterned polymer surfaces, possessing both topographical and chemical characteristics, were prepared on three-dimensional copper tubes and used to capture atmospheric water. The micropatterns mimic the structure on the back of a desert beetle that condenses water from the air in a very dry environment. The patterned coatings were prepared by the dewetting of thin films of poly-4-vinylpyridine (P4VP) on top of polystyrene films (PS) films, upon solvent annealing, and consist of raised hydrophilic bumps on a hydrophobic background. The size and density distribution of the hydrophilic bumps could be tuned widely by adjusting the initial thickness of the P4VP films: the diameter of the produced bumps and their height could be varied by almost 2 orders of magnitude (1-80 μm and 40-9000 nm, respectively), and their distribution density could be varied by 5 orders of magnitude. Under low subcooling conditions (3 °C), the highest rate of water condensation was measured on the largest (80 μm diameter) hydrophilic bumps and was found to be 57% higher than that on flat hydrophobic films. These subcooling conditions are achieved spontaneously in dew formation, by passive radiative cooling of a surface exposed to the night sky. In effect, the pattern would result in a larger number of dewy nights than a flat hydrophobic surface and therefore increases water capture efficiency. Our approach is suited to fabrication on a large scale, to enable the use of the patterned coatings for water collection with no external input of energy.
具有形貌和化学特性的微图案聚合物表面被制备在三维铜管上，并用于捕获大气水。这些微图案模拟了沙漠甲虫背部的结构，能够在非常干燥的环境中从空气中凝结水分。图案涂层是通过在聚苯乙烯（PS）薄膜上的聚 4-乙烯基吡啶（P4VP）薄膜的去湿形成的，在溶剂退火后，由疏水背景上的亲水凸起组成。通过调整 P4VP 薄膜的初始厚度，可以广泛地调节亲水凸起的大小和密度分布：所产生的凸起的直径和高度可以变化近 2 个数量级（分别为 1-80 μm 和 40-9000 nm），其分布密度可以变化 5 个数量级。在低过冷度条件（3°C）下，在最大（80 μm 直径）亲水凸起上测量到的水凝结速率最高，比在疏水平板上高 57%。这些过冷条件是通过表面暴露在夜空中的被动辐射冷却在露水形成中自发实现的。实际上，与疏水平板相比，这种图案会导致更多的露水夜，从而提高水的捕获效率。我们的方法适合大规模制造，可用于在没有外部能量输入的情况下进行集水的图案化涂层。
