Preparation And Application Of Superhydrophobic Materials Based Nano-SiO₂

In recent years,superhydrophobic materials have attracted extensive attention,and their excellent hydrophobic properties have important potential applications in fluid drag reduction,ice protection,dust self-cleaning and oil-water separation.Nano-silica?SiO₂?has been widely used in the preparation of superhydrophobic materials due to its advantages such as simple preparation,small particle size,high chemical purity,good dispersibility and excellent stability.However,there are few applications in dust-proof and self-cleaning of agricultural plastics and metals.And the traditional oil-water separation materials are mainly porous adsorption materials,such as activated carbon,hair,etc.However,these materials have the disadvantages that oil and water are difficult to separate,low separation efficiency,difficult to recycle,and difficult to reuse,which cannot meet the requirements of environmental protection and high efficiency oil-water separation.In this paper,a series of superhydrophobic materials were prepared based on nano-SiO₂.These materials were applied to the surface of PE membranes and stainless steel screens to prevent dust and test their dust resistance.At the same time,these materials are also applied to oil-water separation.It is mainly divided into the following three aspects:?1?Hydrophobic nano-SiO₂ was mixed with ionic liquid to prepare ionic liquid@SiO₂functional material.Then the material was blended with linear low density polyethylene?LLDPE?in a certain ratio to prepare LLDPE with dustproof performance.membrane.The surface of the film was characterized by SEM,and the wettability of the film surface was characterized by the contact angle.The results show that the ionic liquid@SiO₂ LLDPE membrane is more hydrophobic and has a lower surface energy.The amount of dust adhering to the surface is smaller than that of the ordinary LLDPE membrane,whether it is static standing or wind force,so the dustproofness is better.?2?Using acrylic resin as binder,polydimethylsiloxane?PDMS?and hydrophobically modified nano-silica were fixed on the surface of agricultural film by multi-step spraying method to prepare a strong and wear-resistant Transparent polyethylene?PE?film with hydrophobic and dustproof properties,and characterized and tested the material.The results show that the prepared superhydrophobic PE film has high stability and low surface tension?surface energy?,and its surface tension is 23.74 mN/m,which is 12.50 mN/m lower than that of ordinary film,and the visible light transmittance is 86.85%.The contact angle can reach161°,and the dust retention rate on the surface is reduced by 44.7%compared with the ordinary film.Compared with ordinary membranes,hydrophobic PE agricultural membranes have excellent light transmittance,hydrophobicity and dust resistance.?3?Using the surface etching method,the stainless steel filter screen is first etched,and then the surface is loaded with SiO₂ and finally the surface of the filter screen is modified by low surface energy by hexamethyldisilazane.Super hydrophobic stainless steel strainer.The preparation conditions were optimized,and SEM and other characterizations were carried out to test the stability and dustproofness of the superhydrophobic filter.The results show that the prepared super-hydrophobic stainless steel filter has a contact angle with water up to?160±1?°,and has good resistance to ultrasonic and friction.The surface energy is lower,the adhesion to dust is lower,and the dustproof performance is good.?4?A super-hydrophobic and super-lipophilic polyurethane?PU?sponge was prepared by one-pot method,and a polydopamine@SiO₂?PDA@SiO₂?coating was attached to the surface of the sponge together with octyltriethoxysilane.The PDA@SiO₂ PU sponge was obtained by modification at room temperature.The experimental results show that the prepared sponge has a contact angle of up to 168°,which can well absorb the oil on the water surface.Due to the hydrophobic nature of the sponge surface,the water is completely repelled,only the oil is allowed to pass,and then the oil in the sponge is introduced into the oil collecting device by the oil suction device.By this method,various organic solvents such as n-hexane,soybean oil,and petroleum ether can be separated,and the separation efficiency is 85%or more.Moreover,the superhydrophobic sponge can be reused in multiple cycles,and still has good hydrophobicity after 50 cycles.