Incorporation of triarylmethane dyes into sol-gel matrices deposited on textiles

The incorporation of triarylmethane dyes into sol–gel layers formed by modified silica was used for coating of textile materials. The coatings were performed with three triarylmethane dyes differ in electrical net charge and structure: The cationic dye Malachite Green, the anionic Guinea Green and the non-polar Reflex Blue 61. All coating procedures were performed using an acidic sol–gel process starting from a solution of tetraethoxysilane (TEOS) and the dye in a mixture of water and ethanol. Depositions were performed on polyester, polyamide and cotton textiles. Investigation of leaching and photobleaching fastness showed that the stability of the dyes was enhanced by incorporation into the silica layer. Sufficient leaching fastness was only achieved with the cationic dye due to direct attractive electrostatic interaction with the negatively charged silica matrix. Also the addition of a small amount of epoxysilane to the silica sols lead to an enhancement of leaching and bleaching fastness.