The formation mechanism of the contact angle and the sliding angle for a liquid drop on a solid surface plays an important role in producing hydrophobic surfaces. A new half soakage model is established in this paper as a substitute for Wenzel (complete soakage) and Cassie (no soakage) models. The model is suited to many solid surfaces, whether they are hydrophilic or hydrophobic, or even superhydrophobic. Based on the half soakage model, we analyse two surfaces resembling lotus, i.e. taper-like surface and corona-like surface. Furthermore, this new model is used to establish a quantitative relationship between the sliding angle and the parameters of surface morphology.
ZnO micro/nano complex structure films,including reticulate papillary nodes,petal-like and flake-hole,have been self-assembled by a hydrothermal technique at different temperatures without metal catalysts.The wettability of the above film surfaces was modified with a simple coating of heptadecafluorodecyltrimethoxy-silane in toluene.After modifying,the surface of ZnO film grown at 50 C was converted from superhydrophilic with a water contact angle lower than 5 to superhydrophobic with a water contact angle of 165.Additionally,the surface of reticulate papillary nodes ZnO film grown at 100 C had excellent superhydrophobicity,with a water contact angle of 173 and a sliding angle lower than 2.Furthermore,the water contact angle on the surface of petal-like and flake-hole ZnO films grown at 150 C and 200 C were found to be 140 and 120,respectively.The wettability for the samples was found to depend strongly on the surface morphology which results from the growth temperature.
