Sol-gel based water repellent coatings for textiles

Surfaces of cotton, polyester (PES) and polyamide (PA) fabrics have been modified by the sol-gel process in order to achieve silica based hybrid coatings onto the fibers for enhancing their water repellency, thermal stability and mechanical properties. The effects of synthesis parameters such as the concentration of the alkoxysilane used as main precursor, the chloropropyltriethoxysilane (CPTS), and the impregnation time of the fabrics in the solution (sol) prepared have been thoroughly investigated, aiming at the optimization of the targeted properties. Scanning electron microscopy images of the sol-gel treated fabrics exhibit significant differences from the untreated ones. The amount of silicon deposited onto the fabrics was determined by inductively coupled plasma atomic emission spectroscopy. The droplet shapes analysis confirmed that the water repellency of the fabric was dramatically improved after sol-gel treatment. The breaking strengths of the PES and PA fabrics coated with CPTS sols increase with higher sol concentration. Thermogravimetry analyses have been used to assess the thermal stability of treated fabrics. Finally, the influence of accelerated artificial photoageing on water repellency properties was investigated.