Preparation Of Superhydrophobic Materials With Uncontrollable/Controllable Microstructure Surfaces And Their Applications

As the leakage of crude oil and fluid drag problems,development of a special material to deal with such problems has great significance.Superhydrophobic material,which has special wetting property,is famous for the excellent hydrophobic property and low-surface-energy.It is widely used in oil-water separation,drag reduction,surface self-cleaning,anti-corrosion and other fields.So,it has great prospect in researches and applications.In this paper,the superhydrophobic materials with uncontrollable microstructure surfaces were prepared by polymerization method and coating method,and they were applied to realize the efficient oil-water separation.Hot-embossing method was used to prepare superhydrophobic material which had regular microstructure surface with "gas film" sustaining on it for a long time.It provided a theoretical basis for its practical application of drag reduction.Tetraethoxysilane(TEOS)and trimethylchlorosilane(TMCS)were used to modify the hydrophobicity of sponges,both of which were hydrolyzed and polymerized on the surface of sponge skeletons.The surface morphology and compositions,static contact angle,rolling angle and cyclic stress-strain were measured by SEM,EDS,contact angle measuring instrument and other instruments.The modified sponges show excellent hydrophobic property,good oil absorption capacity(about 30 g/g),and high selectivity for oil.On the other hand,the modified sponge has excellent elasticity,and oil and water can be separated by a simple absorption/extrusion method.It can be relpeated at least 200 times for oil-water separations.Three kinds of superhydrophobic mesh materials(copper mesh,filter paper and sponge)were prepared by coating method using polyvinylidene fluoride(PVDF)and hydrophobic silica nanoparticles(H-SiO2)composite materials.Surface morphology and compositions,wetting effect,oil-water separation effect were detected.These three kinds of mesh materials can separate the oil(including organic matter)and water effectively because of their excellent hydrophobic property.And the coating materials have excellent stability,which can be reused without falling off.The superhydrophobic filter paper can reduce the amount of micro-water from 90 ?L/L to about 50 ?L/L in the mineral insulating oil.A polypropylene modified superhydrophobic sponge was prepared by coating method and oil-water separation was carried out by pumping with the sponge.After modification,the sponge shows superhydrophobic property,and can be used for effective cleanup of oil(crude oil)and organic matter(n-hexane).It can also be initially amplified,and has the anti-wind effect.Oil absorption rate was discussed during the process of oil-water separation.In a certain range,the rate of oil absorption increases with the increase of pump speed(the pressure difference between the port and the interface);the oil absorption rate decreases with the increases of oil and water interface distance(including horizontal and vertical distance);the oil absorption rate decreases with the increase of oil viscosity.The superhydrophobic surfaces with regular grating microstructures were prepared on the surface of polytetrafluoroethylene by hot-embossing method.In order to ensure the long-term exist of "gas film" on the microstructures to achieve a sustained drag reduction effect,the electrode materials was put at the bottom of the grids to produce gas maintaining the loss gas in the microstructure of the grids,achieving the result of autonomous controlling of the "gas producing-stop-gas producing" processes,because the electrode materials can form galvanic cells to produce gas or electrolysis can be used to produce gas.Three different aspect ratios(H/L)of the grid microstructures were designed,the grid with H/L about 3 can achieve the effect of gas self-regulation,that is,when the water is squeezed out of the grid,the electrode materials inside of the grid start to produce gas filling the entire grid and squeeze water again.The gas production rates in the case of galvanic cell and electrolysis were discussed.It was found that the farther distance between positive and negative poles,the slower the gas production rate;the higher voltage of electrolysis,the faster the gas production rates.