A Stimulus-Responsive Polymer Composite Surface with Magnetic Field-Governed Wetting and Photocatalytic Properties.

Dániel Sebők,Ákos Kukovecz,Imre Dékány,László Janovák,László Mérai,Ágota Deák

doi:10.3390/polym12091890

Abstract

With the increasing demand for liquid manipulation and microfluidic techniques, surfaces with real-time tunable wetting properties are becoming the focus of materials science researches. In this study, we present a simple preparation method for a 0.5–4 µm carbonyl iron (carbonyl Fe) loaded polydimethylsiloxane (PDMS)-based magnetic composite coating with magnetic field-tailored wetting properties. Moreover, the embedded 6.3–16.7 wt.% Ag-TiO2 plasmonic photocatalyst (d~50 nm) content provides additional visible light photoreactivity to the external stimuli-responsive composite grass surfaces, while the efficiency of this photocatalytic behavior also turned out to be dependent on the external magnetic field. The inclusion of the photocatalyst introduced hierarchical surface roughness to the micro-grass, resulting in the broadening of the achievable contact and sliding angle ranges. The photocatalyst-infused coatings are also capable of catching and releasing water droplets, which alongside their multifunctional (photocatalytic activity and tunable wetting characteristics) nature makes surfaces of this kind the novel sophisticated tools of liquid manipulation.

Highlights

Stimuli-responsive polymers and polymer composites are state-of-the-art products of modern day materials science
Due to its tunable elasticity and hydrophobic nature, PDMS was used as a matrix material during the preparation of magnetoresponsive composite coatings with tunable wetting properties
Upon mixing the two components of the PDMS, the curing took place according to the scheme of Figure 1a [26] for 3 h at room temperature and in ambient air

Summary

Introduction

Stimuli-responsive polymers and polymer composites are state-of-the-art products of modern day materials science. While in the case of 3D materials, there are approaches to influence properties such as swelling degree, bulk density, shape, and size [4], in the case of 2D materials, surface properties could be the subject of stimuli-responsiveness. These properties include surface functionality, charge excess, and roughness [5,6]: manipulating these by external stimuli could result in the reversible change of wetting properties, which is beneficial in microfluidics and other liquid manipulation applications. Many magnetic surfaces with superhydrophobic properties (Θ ≥ 150◦ ) have been developed so far, including magnetic sponges for water-oil separation [7] and hybrid coatings for electromagnetic shielding applications [8], magnetic field-induced wettability transitions are still less studied than systems with electric field [3,9], light [10], temperature [5,6,11], and pH-responsivity [12].

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Results

Conclusion