Preparation of durable superhydrophobic coatings on polyester fabric surfaces and its water-oil separation properties
Objective Superhydrophobic polyester fabrics have been widely used for the fields of self-cleaning and oil-water separation.However,the preparation methods for superhydrophobic fabrics usually involve complex processes and use of fluorine-containing compounds.Fabric finishes with nonfluorinated chemical coatings to attain durable water repellency have attracted broad attention in both academic and industry.This research aims to explore a green and efficient process for preparing durable superhydrophobic polyester fabrics with fluorine-free compounds.Method Polyester fabrics pretreated with oxygen plasma were finished by impregnation method using hydrolyzed solution of methyltrimethoxysilane(MTMS),ammonia water and anhydrous ethanol at the volume ratio of 3∶50∶50.The effect of solution hydrolyzed time on the surface wettability and morphology of the fabrics was analyzed by contact angle measurement and scanning electron microscopy.The surface elemental composition and chemical structure of the polyester fabrics before and after finishing were analyzed by Energy dispersive X-ray spectroscopy(EDX),Fourier transform infrared spectroscopy(FT-IR)and X-ray photoelectron spectroscopy(XPS),and the mechanical properties,stabilities,durability and water-oil separation characteristics of the superhydrophobic polyester fabrics were evaluated.Results The pretreated polyester fabric by low temperature oxygen plasma was finished by MTMS solution with different hydrolytic times.The results showed that the surface of polyester fabric finished with MTMS presented different rough coatings at different hydrolytic times of MTMS solutions,and additional Si elements were found on the surface with the EDX observation.In FT-IR spectrum of the polyester fabric surface before and after MTMS finishing,it was showed that the bending and stretching vibration absorption peaks of Si—CH3 appeared on the finished polyester fabric surface at 1 262 and 779 cm-1 respectively,and the XPS test showed obviously signal peaks of Si 2p and Si 2p.The FT-IR and XPS analysis indicated that the MTMS was successfully finished on the surface of the polyester fabric.In the contact angle test,the MTMS-coated polyester fabrics were all hydrophobic,especially the polyester fabrics with 120-180 min hydrolyzed MTMS treatment reached superhydrophobicity,and the water contact angles were all greater than 150° and the sliding angle was less than 10°.Compared with the untreated polyester fabric,the tensile strength of the polyester fabric with 120 min hydrolyzed MTMS treatment was increased by 8.31％and 11.61％in the warp and weft directions,respectively.After 600 min ultrasonic washing,10 000 abrasion tests,24 h acid and alkaline solution immersion,and 24 h UV aging,the water contact angle of the surface of the superhydrophobic polyester fabric was still greater than 150°.In the five water-oil separation cycle tests,the separation efficiency of polyester fabrics with 90-210 min hydrolyzed MTMS treatment was above 97.0％.Moreover,it also showed good absorption performance in the absorption test with light and heavy oil in water.Conclusion The surface wettability and micro-morphology of polyester fabrics were controlled by MTMS hydrolytic time.The hydrophobic properties of the polyester fabric were enhanced after MTMS finishing,and when the hydrolytic time was 120 min,a rough micro-nanostructure was formed on the surface of the polyester fabric,exhibiting a superhydrophobic state for the polyester fabric.The MTMS-coated polyester fabric had good mechanical properties,and the superhydrophobic coating had excellent resistance to ultrasonic washing,abrasion,acid-alkali corrosion and UV aging,as well as good anti-fouling and water-oil separation properties.This process is green and efficient,and the prepared polyester fabric has a great application potential in water-oil separation,water purification and other fields.
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