Department of Chemistry, College of Staten Island, City University of New York , New York, New York 10314, United States.
ACS Appl Mater Interfaces. 2013 Sep 25;5(18):8915-24. doi: 10.1021/am401668y. Epub 2013 Sep 6.
Multifunctional superhydrophobic nanocomposite surfaces based on photocatalytic materials, such as fluorosilane modified TiO2, have generated significant research interest. However, there are two challenges to forming such multifunctional surfaces with stable superhydrophobic properties: the photocatalytic oxidation of the hydrophobic functional groups, which leads to the permanent loss of superhydrophobicity, as well as the photoinduced reversible hydrolysis of the catalytic particle surface. Herein, we report a simple and inexpensive template lamination method to fabricate multifunctional TiO2-high-density polyethylene (HDPE) nanocomposite surfaces exhibiting superhydrophobicity, UV-induced reversible wettability, and self-cleaning properties. The laminated surface possesses a hierarchical roughness spanning the micro- to nanoscale range. This was achieved by using a wire mesh template to emboss the HDPE surface creating an array of polymeric posts while partially embedding untreated TiO2 nanoparticles selectively into the top surface of these features. The surface exhibits excellent superhydrophobic properties immediately after lamination without any chemical surface modification to the TiO2 nanoparticles. Exposure to UV light causes the surface to become hydrophilic. This change in wettability can be reversed by heating the surface to restore superhydrophobicity. The effect of TiO2 nanoparticle surface coverage and chemical composition on the mechanism and magnitude of wettability changes was studied by EDX and XPS. In addition, the ability of the surface to shed impacting water droplets as well as the ability of such droplets to clean away particulate contaminants was demonstrated.
基于光催化材料（如氟硅烷修饰的 TiO2）的多功能超疏水纳米复合表面引起了广泛的研究兴趣。然而，要形成具有稳定超疏水性的多功能表面，存在两个挑战：疏水性官能团的光催化氧化，这会导致超疏水性的永久丧失；以及催化颗粒表面的光诱导可逆水解。在此，我们报告了一种简单且廉价的模板层压方法，用于制造具有超疏水性、UV 诱导可逆润湿性和自清洁性能的多功能 TiO2-高密度聚乙烯（HDPE）纳米复合表面。层压表面具有跨越微纳尺度范围的分层粗糙度。这是通过使用金属丝网格模板压印 HDPE 表面来实现的，该模板在这些特征的顶部表面选择性地形成了聚合物柱阵列，同时部分嵌入未处理的 TiO2 纳米颗粒。表面在层压后立即表现出优异的超疏水性，而无需对 TiO2 纳米颗粒进行任何化学表面改性。暴露于紫外光会使表面亲水。通过加热表面可以使润湿性发生逆转，恢复超疏水性。通过 EDX 和 XPS 研究了 TiO2 纳米颗粒表面覆盖率和化学组成对润湿性变化机制和幅度的影响。此外，还展示了表面弹离撞击水滴滴的能力，以及这些水滴清除颗粒污染物的能力。
