| Solid surface wettability is mainly determined by surface geometry and chemical compositions.Bioinspired superhydrophobic surfaces with special wettability have important application in both daily life and industrial fields.In recent years,as the single function superhydrophobic surface has matured,its potential to be applied in self-cleaning,corrosion resistance,and wetting conversion has attracted our great interest.At present,despite of the considerable studies on superhydrophobic surfaces,the properties of multi-functional superhydrophobic surface still can not meet people's demand.The current surfaces have a tendency to cause superhydrophobic loss in harsh environment and certain mechanical effect,which are limitations in many applications.Therefore,it is urgent to construct superhydrophobic surfaces with long-lasting performance and multifunction.In this paper,the micro-nanostructures constructed on the surface of brass via sol-gel,self-assembly,electrochemical deposition and nanoparticle filling,and combined with low surface energy modification techniques,a series of multi-functional superhydrophobic composites with good chemical stability and mechanical durability were prepared.The microstructure and chemical composition of the prepared functional surfaces were systematically analyzed.The change of surface wettability was explored,and the relationship between the surface properties and its structure,morphology and composition was established.The mechanism and application of functional surface in wetting conversion,corrosion resistance,self-cleaning,anti-ice-snow were also studied and revealed.The main research contents and results are shown as follows:(1)The superhydrophobic polyvinylidene fluoride/TiO2 composite coating was prepared on brass substrate by sol-gel method and dip-coating process.The impregnating solution is a composite sol of the polyvinylidene fluoride and the TiO2 nanoparticles modified by(heptadecafluoro-1,1,,2-tetradecyl)trimethoxysi-lane.The hydrophobic mechanism,wetting transition law,stability and corrosion resistance of the coating were studied.The results show that the as-prepared coating surface,with a water contact angle of 160.1°,a sliding angle of 5.5° and water absorption of 7.5%,presents micro/nano double rough structure and can capture large amounts of air.Interestingly,the coating surface can realize reversible switching between superhydrophobicity and superhydrophilicity through the alternate treatment by UV light irradiation and heating.Mechanism studies show that this particular stimulus response is caused by the changes in TiO2 lattice composition of the coating.Additionally,the coating not only has good weather resistance,solvent resistance and acid-base resistance,but also shows excellent corrosion resistance that can effectively protect brass substrates from corrosive liquid erosion.(2)Fluorinated polysiloxane resin with low surface energy was obtained using ?,?-bis(hydrogen)-terminated poly(dimethylsiloxane)and dodecafluorohe-ptyl-propyl-trimethoxysilane under the action of Karstedt catalyst.The TiO2/fluorinated polysiloxane superhydrophobic composite coating was prepared via spraying process by fluorinated polysiloxane resin blending with stearic acid modified TiO2 particles.The wettability,microstructure and stability of the coating were studied.The results show that when the weight ratio of TiO2 to fluorinated polysiloxane is 7:3 and the coating heat treatment temperature is 150?,as-prepared coating form“lotus”type multi-layer micro/nano rough structure,with a water contact angle of 162.9°,a lag angle of 4.7° and a water absorption of 7.4%.The coating surface possesses good superhydrophobicity even after 6 months in the outdoor,and can maintains superhydrophobic properties for water droplets with different salt concentrations and pH range of 1?14.The corrosion resistance of the coating was evaluated by electrochemical means.The polarization curve,AC impedance and equivalent circuit analysis show that the presence of the superhydrophobic coating markedly reduces the current of the cathode and anode,causes the corrosion potential moving forward,and effectively prevents the anodic dissolution of brass.The corrosion rate is 1.35×10-3 mm/a,and the corrosion protection efficiency is up to 99.88%,indicating excellent corrosion resistance.(3)The galvanized layer was obtained by electrochemical deposition on the brass substrate,and superhydrophobic zinc surface was formed after modification with stearic acid.The wettability change,microstructure and durability of the zinc surface were studied.The results show that the as-prepared surface with micro/nano-layered rough structure has a water contact angle of 158.3° and a rolling angle of 4.6°.The surface roughness and wettability can be effectively controlled by changing the current density and time of deposition.In addition,the superhydrophobic zinc surface can realize an effective reversible switching between superhydrophobicity and superhydrophilicity after being annealed and modified alternatively,with a fast the wetting switching process costing only 13 min for each cycle.The zinc surface has good chemical stability,but the mechanical stability is relatively weak,and it is easy to lose superhydrophobicity after abrasion with sandpaper.(4)In order to obtain the mechanically stable super-hydrophobic zinc surface,a robust self-cleaning and superamphiphobic TiO2/Zn composite surface was fabricated by a process that involves electrodeposition technology as a tool to construct a micro-scale rough structure,and then uses the low surface energy of nanoparticles-filled rough gap.The surface microstructure,film forming mechanism and self-cleaning properties were studied,and the mechanical stability of the surface was evaluated by various methods.The results show that the surface is composed of sub-micron composite rough structure combined by covalent bonds,which not only has excellent hydrophobic properties,but also excellent repellency toward common corrosive liquids and low-surface-energy substances.The surface maintained its superhydrophobicity after finger-wipe,knife-scratch,sand abrasion,and sandpaper abrasion tests,indicating good mechanical stability.Encouragingly,the surface still exhibits excellent self-cleaning ability even after 50 abrasion cycles with sandpaper and oil contamination.(5)Stable TiO2/polydimethylsiloxane was prepared by filling the rough gap with a low surface energy composite.The wettability,microstructure and stability of the surface were studied,and the anti-icing properties of the surface were also discussed.The results show that the surface wettability change with the sandpaper mesh.Superhydrophobicity of the composite surface is dominated collectively by the micro/nano graded structure and the low-surface-energy materials.The surface can repel hot water in the range of 30?100?,resist to contaminated finger presses,withstand 1.37 kPa of water pressure,and even be resistant to repeated tape stripping and sandpaper wearing.In addition,the surface still remains superamphiphobic rolling properties after snowfall and freeze,indicating excellent initiative anti-ice-snow function. |
PDF Full Text Request