| Wettability is one of the common properties of solid surfaces which can affect the physical/chemical reaction processes and biological activity.In recent years,based on the progress of micro-nano technology,the superhydrophobic material has attracted researchers due to excellent functional properties including anti-fogging,anti-freezing,anti-corrosion,and self-cleaning.Enlightened by the lotus effect,the superhydrophobicity is closely related to: surface roughness in micro-nano scale and low surface energy.Various methods have been developed to fabricate superhydrophobic surfaces.However,most of them cannot be commercialized due to the following challenges:(1)From the perspective of technology,most of the fabrication methods still relied on the expensive equipments,toxic reagents,complicated processing and poor reproducibility.In addition,they were only suitable for small-scale fabrication but mass production;(2)From the perspective of stability,the most reported superhydrophobic surfaces had poor resistance to chemical corrosion,mechanical abrasion and temperature;(3)From the perspective of performance evaluation,most of the researches only focused on the wettability of the fabricated surfaces,such as the static contact angle and rolling angle.It lacks of systematic,qualitative and quantitative evaluation which relate to real conditions.Therefore,it is important to develop new techniques on superhydrophobicity,which is flexible and convenient,high reproducible,and cost-effective,that suitable for mass production.In this dissertation,we report a new technique,called template assisted chemical vapor deposition(TA-CVD),to deposit porous silica film and/or fibred-silica network film on glass and copper mesh.Respectively,transparent superhydrophobic glass with self-cleaning and superhydrophobic-superoleophilic filter mesh with oil/water separation were achieved.Systematic and quantitative evaluation was conducted on the prepared glass and copper mesh with respect to wettability,transparency,oil/water separation ability and stability.The main research and results are listed as following:1.Using soot film as template,a layer of porous silica film was deposited on the soot film on the glass substrate by TA-CVD.Self-cleaning transparent glass with perfect superhrophbility was fabricated by controlling the deposition parameters,including the thickness of soot film,silica deposition temperature,silica deposition time,and annealing temperature and time.The water contact angle(CA)of was 158°,the rolling-off angle(RA)was 1°,and the transparency was 90%.The superhydrophobicity was kept after immersion in acid/alkali solution and put at high temperature environment.In addition,after 12 liters of water flow,superhydrophobicity was not changed,which shows excellent mechanical stability.2.Using soot film as template,a layer of fibred-silica film was deposited on soot film on glass substrate by TA-CVD.After modified with HMDS,superhydrophobicity was achieved.By adjusting the airflow during annealing,the surface morphology changed from porous structure to fibred-network structure.The influence of soot film thichness,silica deposition temperature,silica deposition time,annealing temperature and time to the wettability and transparency were systematically investigated.Transparent self-cleaning glass was achieved.The water CA was 166°,the RA was 1°,and the transparency was about 88%.The superhydrophobicity was kept after immersion in acid/alkali solution,sodium chloride solution and put in high temperature environment,which indicate excellent chemical resistance and thermal stability.Finally,the mechanical property was evaluated.After 20 liters of water flow and 100 g of sand grains,superhydrophobicity was not changed.3.Using TA-CVD,a thin layer of porous silica was deposited on soot film on copper mesh substrate.After modified by HMDS,the water CA was 158°,the water RA was 1°,while the oil CA was 0°.Such copper mesh could be used in water-oil separation.The wettability and oil/water separation(OWS)ability of the copper mesh were studied with the following parameters,including the thickness of soot film,silica deposition temperature,silica deposition time,and annealing temperature and time.The as-prepared superhydrophobic-superoleophilic filter mesh could effectively separate immiscible oil-water mixture,and the separation efficiency was higher than 98%.The filter mesh showed good stability to chemical corrosion and high temperature.In addition,the filter mesh showed good mechanical stability with 12 liters of water flow and 40 g of sand grains.4.Using TA-CVD,a layer of fibred-silica network film was fabricated on soot film on copper mesh substrate.After modified with HMDS,superhydrophobicity and superoleophilicity were achieved.The water CA was 165°,the water RA was 1°,and the oil CA was 1°.The porous structure was changed to fibrous structure with airflow during the annealing.A new design of tubular separation device with 10 cm of length and 3 cm of diameter was used for OWS.OWS efficiency was over 99%.In addition,the mesh also had excellent resistance to chemical corrosion and mechanical abrasion.The performance was better than that of the porous film coated superhydrophobic-superoleophilic filter mesh.Finally,in order to meet the demand of practical waste water treatment,we developed a simple and effective oil-water separation device which is composed of oil-water separation tube and a pump and it has great practical potential.5.Using high-temperature CVD at the back side of the porous film coated superhydrophobic-superoleophilic filter mesh,the fibred-silica film coated copper mesh was changed to the fibred-silica coated mesh.The fibred-silica film could cover the copper mesh pore as well as the copper wire.After modified with HMDS,the surface showed superhydrophobic and superoleophilic properties.The water CA was 152°,and the oil CA was 0°.The modified mesh could not only effectively separate immiscible oil-water mixtures,but also effectively separate water from oil emulsion. |
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