Photocatalytically active TiO2 – silicone rubber

Abstract

Bacteria are present in all areas of everyday life and can lead to dangerous infections. Surfaces with antimicrobial properties are used to reduce the risk of infection in sanitary facilities and hospitals. Apart from the addition of biocides or antibiotic agents to synthetic materials, recent research show, that it is possible to use the semiconductor titanium dioxide (TiO2) to generate antibacterial surfaces. The photocatalytically active TiO2 leads to the development of reactive oxygen species (ROS) that are able to kill bacteria. The aim of this research is to generate silicone rubbers with a photocatalytically active surface that has the possibility to lead to an antimicrobial property by incorporating the additive TiO2 into the bulk material. AEROXIDE® TiO2 P25 was used. As matrix material representatives of the three silicone rubber classes were tested. A room-temperature-vulcanization silicone rubber (RTV), a liquid silicone rubber (LSR) and a high-temperature-vulcanization silicone rubber (HTV) were examined. Compounds with various concentrations of TiO2 were produced and the influence on the cross-linking reaction was investigated using differential scanning calorimetry (DSC). The photocatalytic effect on the surface of the modified material was studied via contact angle measurements and methylene blue tests. The DSC analysis showed that titanium dioxide inhibits the curing of the additivated RTV and LSR. The incorporation of TiO2 in the HTV matrix material up to 15 wt% was possible, with an extension of the cross-linking time. The investigation of the HTV siivone rubbers considering the photocatalytic effect yield different results. While the expected photo-induced hydrophilic effect could not be verified for the modified HTV silicone rubbers. However the methylene blue trial showed a high significant discoloration of the titanium dioxide addtivtated HTV polymer and proves that a photocatalytic active HTV silicone rubber surface can be produced using the additive titanium dioxide.