Preparation, Property And Application Of Super Water-Repellent Surfaces

In this work, super water-repellent surfaces have been prepared by the solidification method on the basis of wax compounds such as triglycerides and alkylketene dimer (AKD), and the formation mechanism, kinetics and characteristics of such super water-repellent surfaces have been discussed.Various water-repellent surfaces were prepared by binary mixtures of trimyristin (MMM) and tripalmitin (PPP) with different mole fraction (xppp). Contact angle measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to investigate the formation of the super water-repellent surfaces. The values of the fractal dimension (FD) describing roughness of these surfaces were calculated, and the formation mechanism of such surfaces was discussed. It turns out that the spontaneous formation of fractal structures results from the phase transformation from the metastable state to a stable crystalline state. According to the results of time-dependent contact angles of water droplets on surfaces incubated at different temperatures, kinetic constants and the values of activation energy of the formation of super water-repellent surfaces are further obtained.The evaporation of water droplets on water-repellent surfaces with different initial contact angles made from triglycerides and AKD has been studied. It follows that the evaporation process is affected by the hydrophobicity of such surfaces, but free from the influence of the initial volumes of the water droplets. Assuming that the shapes of the water droplets on the surfaces are spherical caps and the evaporation process fit the vapor diffusion model, the vapor pressure difference (△pv) between the vapor pressure on the drop surface and that at a considerable distance far from the drop can be obtained. The Apv values can reflect the rate of evaporation.The C6glioma cells were cultured on the water-repellent surfaces made from tripalmitin(PPP) with different fractal dimensions. Using the poly-L-lysine (PLL) coated surface as a reference surface, the role of fractal surfaces in C6glioma cell differentiation were investigated. The number of C6cells decreased as the FD values of the PPP surfaces increased. The FD values of the cells increased as the culture time increasing when cultured on one PPP surface, and they also increased as the FD values of the PPP surfaces increasing under the same culture time. The results indicate that the fractal surfaces can induce the actin and tubulin rearrangements and change the morphology of the C6glioma cells.Super water-repellent composite particles were prepared with surfaces modified composite particles of CaCO3/SiO2, and super water-repellent coatings were obtained on basis of these particles. The formation mechanism of such super water-repellent surfaces was discussed by SEM, infrared spectrometry (IR) and thermogravimetry (TA) measurements. The results indicate that the roughness induced by nano and micro-scale patterns on surfaces of modified composite particles is the main factor influencing the surface hydrophobicity. With contrast of the investigations on above two kinds of surfaces, better knowledge about the formation of the super water-repellent surfaces has been gotten.