Multifunctional water and oil repellent and antimicrobial properties of finished cotton: influence of sol–gel finishing procedure

Cotton fabric was treated with two-component water- and oil-repellent antimicrobial coatings consisting of the commercial aqueous organic–inorganic hybrid precursors fluoroalkyl-functional siloxane (FAS) and 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (SiQAC) of different concentrations. Two different application procedures were used: a one-step treatment (S1) by a sol mixture consisting of both precursors [coating FAS-SiQAC (S1)] and a two-step treatment (S2) by SiQAC sol and then FAS sol [coating SiQAC + FAS (S2)]. The functional properties of the coatings were determined from liquid contact angle measurements and antimicrobial activity, as well as FTIR and XPS analyses. Although both treatments gave the cotton fabric superhydrophobic and oleophobic properties at a sufficient sol concentration, procedure S1 was found to be more effective than procedure S2. The antibacterial properties of the SiQAC + FAS (S2) coating were superior to those of the FAS-SiQAC (S1) coating. For both two-component coatings, the active bacteriostatic activity of SiQAC was enhanced by the passive antibacterial activity of FAS. Two-component coatings did not provide significant antifungal protection. Repetitive washing gradually deteriorated both coatings but the coating applied by procedure S2 seemed to be slightly more durable than that applied by S1. The two-component coatings caused an increase in the flexibility and a slight decrease in the fabric breaking strength and air permeability of the cotton sample.