Hydrophobic sol-gel finishing for textiles: Improvement by plasma pre-treatment

The surface of cotton (COT) and polyester (PET) fabrics was modified to create a water-repellent finishing by depositing a modified silica-based film using the sol-gel technique. TEOS (tetraethoxysilane)-based physically modified sols with 2% and 11% on weight fabric (o.w.f.) of hydrophobic additives were tested. N-propyltrimethoxysilane (C3), hexadecyltrimethoxysilane (C16) and 1H,1H,2H,2H-fluorooctyltriethoxysilane (FOS) were investigated as additives. Furthermore, a low-temperature plasma pre-treatment was used to activate the COT and PET fabric surface to improve the sol-gel coating adhesion, resistance to abrasion and fastness to washing stresses. A complete chemical/morphological (Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscopy) and physical characterization (abrasion and air permeability test) of treated samples was carried out. High values of (around 140 degrees) on PET and COT samples were obtained with all additives used (C3, C16 and FOS) even at a low concentration (2%). Due to plasma pre-treatment, interesting water-repellent properties were achieved for PET (=148 degrees) treated with TEOS/FOS molar ratio 0.63 and for COT (=140 degrees) with TEOS/C16 molar ratio 0.63. The enhanced coating adhesion, due to plasma surface activation, was confirmed by abrasion and washing tests.