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 COTand 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 y (around 140) 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 (y¼148) treated with TEOS/FOS molar ratio 0.63 and for COT (y¼140) with TEOS/C16 molar ratio 0.63. The enhanced coating adhesion, due to plasma surface activation, was confirmed by abrasion and washing tests.