Highly hydrophobic and UV protective properties of cotton fabric using layer by layer self-assembly technique

Electrostatic self-assembly layer by layer technique was used to immobilize ZnO/SiO₂ nanocompsite on cationized cotton fabric. This occurs via the sequential dipping of cotton fabric in dilute solutions of poly (diallyldimethylammonium chloride) (PDDA) and ZnO/SiO₂ colloidal suspension nanocomposite of different concentration ratios 1:0, 0:1, 1:1, 2:1, 1:2, and 2:2. The formation of multilayer thin film on cotton fabric creates different functional properties. UV protection properties were monitored at the ratio of (Zn/Si) as well as the number of layers. In the case of 1(Bilayer)BL and 5(Bilayer)BL, increasing the ratio of (ZnO/SiO₂) within the nano composite (ZnO/SiO₂) ratio, the UPF increases and the results indicate that the best ultraviolet protection factor is obtained when the Zn/Si ratio is 2. Additionally, dyeing the treated fabric often enhanced protection against ultra violet rays. FTIR spectra were utilized to distinguish the existence of effective groups on the surface of the treated cotton. Scanning electron microscopy studies confirmed successful deposition of the PDDA/(ZnO/SiO₂) nanocomposite. Moreover, cotton fibers connected together because of the increased coating density and their surface become rougher. Post treatment by stearic acid rendered the fabric water repellent property. Other physical properties such as tensile strength as well as breathability of the cotton fabric were investigated.