Preparation of superhydrophobic PET fabric from Al2O3–SiO2 hybrid: geometrical approach to create high contact angle surface from low contact angle materials

In this work we prepare high contact Poly Ethylene Terephthalate (PET) fabric surface from low contact angle materials. Superhydrophobic PET fabric is prepared by coating the fabric with hybrid Al2O3–SiO2 sol. In this case, the high contact angle Al2O3–SiO2 hybrid is created from low contact angle Al2O3 and SiO2 precursors. PET treated with hybrid Al2O3–SiO2 exhibit Water Contact Angle (WCA) as 150°, while PET treated with individual Al2O3 sol or SiO2 sol exhibits lower WCA, (Al2O3 WCA = 137°; SiO2 WCA = 141°). FESEM and AFM investigations show that the hybrid Al2O3–SiO2 sol and individual Al2O3 or SiO2 sol imparted different roughness geometry on the PET fabric surface. We observe surface structure of fish fin-like, particle-like and hybrid fin-particle for treated PET fabric with; Al2O3, SiO2 and hybrid Al2O3–SiO2 sol, under FESEM and AFM observations.AFM observations show the evolution of roughness (Ra) dimension of different surface structures with the order of: SiO2 < Al2O3 < Al2O3–SiO2 (Ra = 31, 63 and 273 nm). We believe that the disparity of the surface geometries lead into different surface WCA. FTIR spectra of Hybrid Al2O3–SiO2 shows additional peak at 902, 850, 557, and 408 cm−1 which can be ascribed to the hybridization structure.