Superhydrophobic TiO₂–Polymer Nanocomposite Surface with UV-Induced Reversible Wettability and Self-Cleaning Properties

Abstract

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.

Comparative study of the effects of anatase and rutile titanium dioxide nanoparticles on the structure and properties of waterborne polyurethane

“…Nowadays, being used as inorganic additive into polymers has attracted much more attention [3][4][5]. The addition of nano-TiO 2 into polymers can not only improve the UV resistance [6] and mechanical properties [7], but also endows some functional properties, such as photocatalytic antibacterial [8,9] and photocatalytic self-cleaning [10][11][12].…”

Recent Progress in Self-Cleaning Materials with Different Suitable Applications

“…This technique, because of its different applications, has attracted researchers' attention that focused on controlled wetting properties (Wang et al, 2014b;Li et al, 2013b;Xu et al, 2013b;Zhang et al, 2013a;Crick et al, 2012). This is a 'smart coatings' which has the ability to switch from time to time to hydrophilic and hydrophobic surfaces by light irradiating under specific wavelength (Wooh et al, 2014;Nandan et al, 2015).…”

Stably superhydrophobic (IL/TiO2) hybrid films: Intelligent self-cleaning materials

“…hydrophobic functional groups, which leads to the permanent loss of superhydrophobicity, as well as the photoinduced reversible hydrolysis of the catalytic particle surface under UV irradiation, rendering to hydrophilicity. [37,38] To investigate the photoinduced wetting conversion and the stability of (IL/TiO 2 ) n nanocomposites, we irradiated the [C 12 mim]Br/TiO 2 ) 13 films with UV light at 365 nm for 2 hrs. The experimental results showed that the CAs became to be about 10 o (Fig.…”