Antimicrobial SiO2 wood-inorganic composites as prepared by the sol-gel process with water-soluble silicon oligomer agents

A previous study of the wood-inorganic composites prepared by the sol-gel process indicated that SiO2 wood-inorganic composites with 3-trimethoxysilylpropyldimethyloctadecyl ammonium chloride (TMSAC) or 3-trimethoxysilylpropyl(carboxymethyl)decylmethyl ammonium inner salt (TMSAH) have good antimicrobial properties. However, one of the obstacles to the industrial application for this process is the use of alcohol as a solvent, because alcohol is flammable and its recycling is necessary. Therefore, we propose in this study the use of water instead of alcohol as a solvent to prepare antimicrobial SiO2 wood-inorganic composites. Using the sol-gel process, decyltrimethoxysilane (DTMOS) or 2-heptadecafluoroocthylethyltrimethoxysilane (HFOETMOS) as a water-repellent agents were bound with the silicon oligomer to which aminopropyltrimethoxysilane (APTMOS)-acetic acid salt was introduced to make this water-repellent agent stable in the water system. To this system, TMSAC was added with distilled water to enhance the antimicrobial property. As a result, water-soluble silicon oligomer agents were successfully prepared to be stable and water-repellent property even after 1 month of their preparation. The wood-inorganic composites prepared with these agents in the water system were found to have good antimicrobial properties as good as were obtained by the alcohol system.