Applied Surface Science, Vol.253, No.4, 1873-1881, 2006
Structural, morphological, wettability and thermal resistance properties of hydro-oleophobic thin films prepared by a wet chemical process
The structural properties of fluorine containing polymer compounds make them highly attractive materials for hydro-oleophobic applications. However, most of these exhibit low surface energy and poor adhesion on the substrates. In the present investigation, crack free, smooth and uniform thin films of poly [4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole]-co-tetrafluoroethyle ne (TFD-co-TFE) with good adhesion have been deposited by wet chemical spin-coating technique on polished AISI 440C steel substrates. The as-deposited films (xerogel films) have been subjected to annealing for I h at different temperatures ranging from 100 to 500 degrees C in an argon atmosphere. The size growth of the nano-hemispheres increased from 8 nm for xerogel film to 28 nm for film annealed at 400 degrees C. It was found that as the annealing temperature increased from 100 to 400 degrees C, nano-hemisphere-like structures were formed, which in turn have shown increase in the water contact angle from 122 degrees to 147 degrees and oil (peanut) contact angle from 85 degrees to 96 degrees. No change in the water contact angle (122 degrees) has been observed when the films deposited at room temperature were heated in air from 30 to 80 degrees C as well as exposed to steam for 8 days for 8 h/day indicating thermal stability of the film. (c) 2006 Elsevier B.V. All rights reserved.