Preparation And Properties Of Hydrophilic Nano-composite Coating For Antimicrobial And Self-cleaning

With the increasing of global population, the warming of the climate and the pollution of environment, people are prone to be attacked by ubiquitous pathogenic microorganisms at any moment. Sanitary conditions of living environment have attracted more attention. In addition, atomizing and surface adhesive pollutants(dust, organic compounds, etc) affect the visibility of glass, which can be also polluted by pathogenic microorganisms because of insufficient cleaning. It is necessary to explore a multifunctional material including antimicrobial, antifogging and self-cleaning.Using the polyurethane(PU) resin modified by anion surfactant and titanium dioxide(TiO2), the hydrophilic nano-composite coating and the following PU/TiO2complex film(HPTF)were prepared. The characteristics of the HPTF were described by Fourier-transform infrared spectrometry (FT-IR), ultraviolet-visible spectroscopy (UV-vis). The combination of the dodecyl sulfonate group and titanium dioxide with polyurethane was found via FT-IR. The absorption spectrum of HPTF red shifted to visible light relative to the naked particles, and strong absorption was observed. Photocatalysis of HPTF under visible light in the experiments showed that the apparent optical bandgap (Eg) of HPTF shifted to a lower value compared with that of bulk TiO2because of the dielectric confinement effect and dipole effect. Simultaneously, the antimicrobial activities of the HPTF were also studied. The results indicated that, after8h, nearly all of the E. coli and C. albicans could be killed under visible light irradiation; and the antimicrobial activity was evidently better than pristine polyurethane film. The antimicrobial ratio of the HPTF on A. niger reached70%after8h. The optimal TiO2amount in the HPTF preparation was0.25g (TiO2)/100ml (emulsion). The antimicrobial activity of the HPTF under visible light was in accordance with the UV-vis absorption spectra. Long-lasting antimicrobial activity was also showed by the coating, and99%antimicrobial ratio was obtained after3months.The antifogging and self-cleaning abilities of the HPTF were studied. Hyaloid water film was formed on more than95%area of the HPTF within5min indicated good antifogging of HPTF. The degradation rates of Methyl Orange(MO), Methylene Blue(MB) and Sunset Yellow(SY) reached23%,21%and98%, respectively, after6h under UV irradiation. And the dust on HPTF can be easily and neatly taken away by water. The HPTF also showed excellent mechanical properties via the studies on acid-base resistance, organic solvent resistance, cold/heat resistance and antiwear performance.