Visible light-photoreactive composite surfaces with thermoresponsive wetting and photocatalytic properties

With the increasing demand for liquid manipulation and microfluidic techniques, surfaces with external stimuli induced real-time tunable wetting properties are getting into the focus of materials science research. In this study, we present poly(dimethylsiloxane) (PDMS) copolymer-based composite coatings with thermally adjustable wetting and visible-light photoreactivity. To give thermal responsivity to the spray-coated or doctor blade-casted PDMS surfaces, they were grafted with poly(N-isopropylacrylamide) (PNIPAAm), applying the Activators Regenerated by Electron Transfer - Atom Transfer Radical Polymerization (ARGET-ATRP) method. As the lower critical solution temperature (LCST) of the grafted PNIPAAm chains appeared to be 34 degrees C, the copolymer films showed thermoresponsive, and PNIPAAm surface concentration-dependent wetting characteristics. The addition of 15 wt% visible light-active plasmonic Ag-TiO2 photocatalyst nanoparticles (d(primary) similar to 50 nm) enriched the coatings with photocatalytic activity, which was also proven to be temperature-dependent during methylene-blue (MB; c(0) = 6.25 mM) photodegradation tests (blue LED-light, lambda = 405 nm) at the S/L-interface. Thanks to the real-time tunable wetting and photocatalytic properties, the presented coatings may offer a novel route towards sophisticated liquid manipulation.

Automated summary

This study presents PDMS composite coatings with thermally adjustable wetting and visible-light photoreactivity. The PDMS surfaces were grafted with PNIPAAm to provide thermal responsivity and surface concentration-dependent wetting characteristics. The addition of visible light-active plasmonic nanoparticles enriched the coatings with temperature-dependent photocatalytic activity. These coatings may offer a novel route towards sophisticated liquid manipulation due to their real-time tunable wetting and photocatalytic properties.