Preparation and Properties of Water Repellent Polystyrene-TiO2 Coatings

Recently, there has been a great demand for hydrophobic (contact angle >90 degrees) and super-hydrophobic surfaces (contact angle >150 degrees) in industry for a variety of applications due to their easy to clean nature. In the present study efforts have been made to prepare hydrophobic polymer nanocomposite coatings containing titania nanoparticles. Titanium dioxide (TiO2) powders have been prepared by hydrothermal and co-precipitation methods and have been characterized by X-ray diffractometry, field emission scanning electron microcopy (FESEM) and Raman spectroscopy. The Raman and XRD studies confirm the presence of anatase titania for the hydrothermal synthesized and commercial titania powders. Titania derived from precipitation technique contains 68% rutile titania. Polymer based nanocomposite coatings have been prepared using polystyrene (PS) as the matrix and titania nanopowders as the dispersed phase. The obtained coatings have been characterized for contact angle and microstructure. Of the three sources of TiO2 used hydrothermal TiO2 gives higher contact angle values. Heating the THF-PS-TiO2 solution to a temperature of 50 degrees-60 degrees C helps in increasing the water contact angle (WCA). The FESEM images of PS-TiO2 coatings reveal microstructure akin to the fibers produced by electro-spinning method. The X-ray mapping pattern of PS-TiO2 confirm the presence of carbon (polystyrene) and titanium elements. Even a small amount (0.03 g) of hydrothermal Mania with 0.7 g of polystyrene gives a WCA as high as 149.77 degrees which is close to the WCA of super hydrophobic range.