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.
A luminescent superparamagnetic nanocomposite with an Fe 3 O 4-SiO 2-CdS structure is synthesized.Coated with a silica shell,Fe 3 O 4 nanoparticles and CdS quantum dots (QDs) are successfully assembled together.Analysed from the test results of X-ray diffraction (XRD),transmission electron microscopy (TEM),high resolution transmission electron microscopy (HRTEM),hysteresis loop,and photoluminescence (PL) spectrum,these nanocomposites exhibit superparamagnetic and photoluminescent properties.
Alternative Ag and SiO 2 multilayers are prepared by using radio frequency magnetron sputtering.The Ag particles are found to diffuse toward and mostly accumulate near the surface of the Ag-SiO 2 composite film via a rapid thermal treatment.Different shapes of the Ag particles are obtained by changing the thickness of each Ag and SiO 2 layer.The response absorption property of the Ag composite film is also investigated.We relate the resonance absorption to the surface level and the Fermi level.To induce the obvious resonance absorption in an Ag composite film,it is necessary to maintain special shapes with sharp edges and wide terraces and to maintain the particle sizes ranging from 0 nm to 100 nm.
The ability of nanoscaled ZnO films to enhance fluorescence was studied.We found that the fluorescence intensities of Cy5,rhodamine 6G,and fluorescein can be enhanced about 10-fold on nanoscaled ZnO films as compared to that on glass substrates.The lifetimes of all samples were measured,and no obvious change in lifetime was observed for dyes on different substrates.The mechanism for the nanoscaled ZnO film enhanced fluorescence appears to be different from that for the metal-fluorophore systems.
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.
