Stable Photocatalytic Paints Prepared from Hybrid Core-Shell Fluorinated/Acrylic/TiO2 Waterborne Dispersions

Audrey Bonnefond,Giulio Brinati,Sami Rtimi,Cesar Pulgarin,Edurne González,Alessandro Veneroni,Alessio Marrani,Eliana Ieva,Jose Leiza,José Asua,John Kiwi,Serena Carella

doi:10.3390/cryst6100136

Abstract

The contamination of air and water is one of the major concerns towards the development of a sustainable world in the 21st century. In this context many efforts are devoted to the design of photocatalytic paints able to degrade chemical and biological impurities present in air and water. In this work, the photocatalytic activity of hybrid films formed from the blends of pure acrylic or core/shell fluorinated/acrylic waterborne dispersions and photocatalytic titanium dioxide (TiO2) nanoparticle dispersions was first assessed. The films show photocatalytic activity (inactivation of the Escherichia coli bacteria under UV irradiation) at the substrate-film interface, but very reduced activity in the air-film interface due to the substantially lower amount of the TiO2 nanoparticles in the vicinity of this interface. In a second step, the fluorinated/(meth)acrylic core-shell hybrid dispersions were used as binders in the formulation of waterborne photocatalytic paints and the stability of the paints, in terms of gloss retain and color change, was assessed during 5000 hours of accelerated weathering tests (QUV-B). Although a decrease in gloss retention and increased color change occurs during the first 1000 hours of exposure, no further change of these properties takes place, which is an excellent indication of stable photocatalytic paints.

Highlights

The recent awareness of the threat to human health and to the environment of air and water pollutants has led scientists to search for a new technology able to reduce the contaminants’concentrations
This paper describes the preparation of photocatalytic paints using two types of polymeric binders (a pureacrylic latex and a fluorinated/(meth)acrylic latex with core-shell morphology) and two types of photocatalytic TiO2 nanoparticles
The photocatalytic activity of the TiO2 nanoparticles embedded in a polymeric matrix was assessed by analyzing the inactivation of Escherichia coli bacteria on films produced from hybrid dispersions obtained by blending the TiO2 aqueous dispersions and each of the latexes

Summary

Introduction

The recent awareness of the threat to human health and to the environment of air and water pollutants has led scientists to search for a new technology able to reduce the contaminants’concentrations. Crystals 2016, 6, 136 generate heat, in some cases the photocatalytic phenomena takes place and electrons and holes reach the surface of the photocatalyst where they can participate in redox reactions with the present oxygen and water molecules, creating highly active radicals. These radicals are able to decompose organic compounds and bacteria and, they are able to clean surfaces [4,5,6]. Since the surface of the photocatalyst becomes superhydrophilic under UV irradiation, it is claimed that photocatalytic materials might have self-cleaning properties [7]

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Results

Conclusion