Sol-gel synthesis and hybrid thin film deposition for innovative textile finishing. Study, characterization and environmental impact evaluation

Abstract

The aim of the present work was to study and characterize a new approach to finish textile fabrics. This new approach is based on the production of a thin film on textile surface containing metal-organic precursors. Organic-inorganic hybrid thin films based on silica or titania sols were thus developed by sol-gel process for flame retardant, hydro-repellent and self cleaning fabrics. The proposed hybrid compounds for textile finishing are expected to help the development of new finishes, constituting a valid alternative to the well established commercially available treatments of textile. In fact, traditional treatments could have several disadvantages: they could be hazardous materials for the workers during production and application, and for end-users who wears the treated cloths. Moreover, they are responsible for water pollution and for high energy consumption. Halogen free flame retardants hybrid films were realized to enhance the thermal and fire stability of cotton. To this aim specific combination of silica precursor (3-aminopropyltriethoxysilane (APTES) and diethylphosphatoethyltriethoxysilane (DPTES)), phosphorus donors (diethylphosphite (DEP) and DPTES) and nitrogen donors (APTES and melamine-based resin (MF)) were tested. Free fluorocarbon water repellent hybrid films were then realized onto cotton and PES fabrics using octyl triethoxysilane (OTES) as precursor and MF as cross-linker. Three different MF concentrations and four MF:OTES molar ratios were evaluated. The self cleaning study was finally developed following two main research approaches. In the first one, stable aqueous titania sols were synthesized at suitable pH for the industrial application without the addition of alcohols, glycol or acetyl acetone. In the second one, TiO2 thin film coatings were realized on cotton fabrics by sol-gel technique. The effect of different starting acidic solutions (nitric, hydrochloric and acetic acids) and the addition of polyethylene glycol (PEG) onto two different TiO2 concentrations were investigated.