Durable, highly hydrophobic modification of cotton fabric with fluorine-free polysiloxanes obtained via hydrosilylation and hydrothiolation reactions

Abstract

Cotton fabrics were subjected to modification with fluorine-free polysiloxanes. In the first stage a series of polysiloxanes substituted with alkoxysilyl groups and/or alkyl chains were synthesized. Two methods of functionalization of vinyl group-containing polysiloxanes were used, i.e. hydrosilylation and hydrothiolation. Cotton fabrics were modified via dip-coating technique in solutions of the prepared compounds or by thiol–ene click reaction directly on the surface of cotton. In the first stage of the latter method cotton fabrics were modified by sol–gel technique with 3-mercaptopropyltrimethoxysilane in order to obtain mercapto-functionalized samples. After grafting SH groups on the surface, the fabrics were easily functionalized using the photoclick thiol–ene reaction with vinyl groups containing polysiloxane or vinyl- and alkyl-groups containing polysiloxane. The hydrophobicity was determined by measuring the water contact angle. Changes in the surface morphology were examined by FTIR spectroscopy and scanning electron microscopy (SEM). The coatings of the modified fabrics were subjected to elemental analysis using SEM–EDS techniques. All modified cotton fabrics showed highly hydrophobic properties. All obtained hydrophobic fabrics were fully resistant to the washing process, which proves the durability of the developed modifications.