Preparation And Properties Of Nano-SiO₂/BPH-8 Gel Composite Superhydrophobic/Super Slippery Surface

Inspired by nature,researchers have developed a large number of superhydrophobic/super slippery surfaces with composite structures at micro-and nanoscales.These materials with special surface wetting properties are widely used in the fields of anti-fouling and dust removal,underwater drag reduction,antibacterial,corrosion resistance,and oil-water separation,which have great potential.After decades of efforts,a variety of methods for the preparation of micro-and nanostructures have been developed.Among them,the molecular self-assembly method has the advantages of simple process equipment requirements and no substrate material restrictions.The low molecular weight organogel factor has excellent self-assembly properties in solvent,which can be applied to a variety of substrate surfaces to achieve large-scale preparation of coatings.Our group has successfully prepared superhydrophobic surfaces using 1,4-bis[（3,4-bisoctyloxyphenyl）hydrozide]phenylene（BPH-8）gel factor,but the surface still has defects such as high adhesion to liquid droplets and poor wear resistance and durability.To address these problems,in this thesis,fluorosilane modified SiO₂nanoparticles（F-SiO₂）were introduced into the BPH-8 organogel system to prepare the inorganic nanoparticle/organogel composite self-cleaning superhydrophobic coating.Based on this,the coating was combined with metallic materials,and the metal microarray formed by laser etching was used as the"armor"to protect the superhydrophobic coating and improve the friction resistance of the coating.Finally,the superhydrophobic surface is transformed into a superslip surface by injecting a low surface energy lubricant to further improve the hydrophobicity of the coating.At the same time,the superhydrophobic/superslip surface can prevent the corrosive liquid from contacting the metal substrate and give the metal material good corrosion resistance properties.The main research contents and results of this thesis are as follows:（1）The F-SiO₂/BPH-8 composite superhydrophobic coating was prepared by using BPH-8 gel factor and F-SiO₂ nanoparticles as raw materials.The introduction of nanoparticles can effectively improve the wettability of the coating surface.When the mass ratio of F-SiO₂ and BPH-8 gel factor is 10:100,the rolling angle of the coating surface is reduced to within 10°;when the mass ratio of the two is increased to 70:100,the contact angle of the coating reaches 170°and the rolling angle is about 2°,which achieves the best superhydrophobic state.The coating has excellent self-cleaning ability and underwater durability,and is suitable for a variety of substrates（metal,paper,glass）.（2）Microstructures with a certain depth were formed on the brass surface by laser etching,after which the F-SiO₂/BPH-8 superhydrophobic coating was filled between these microstructures to obtain metal samples with superhydrophobic properties.We investigated the effects of different laser parameters（scan spacing,scan power,scan speed）on the microstructure morphology of the metal surface and the abrasion resistance of the coating.The results show that the different morphologies of the microstructures can improve the friction resistance of the superhydrophobic samples,and the best wear resistance of the surface coating was achieved when the scanning pitch of the laser beam was 50μm,the scanning power was 11 W,and the scanning speed was 100 mm/s,and it was maintained at 150.3°after 20 friction cycles.The results of electrochemical tests showed that the corrosion potential of the superhydrophobic brass sample increased from-289.8 m V to-238.7 m V of the original sample,and the corrosion current density decreased from 8.65*10^-5 A/cm2 to 8.38*10^-7 A/cm²,a decrease of two orders of magnitude,and the corrosion resistance efficiency reached 97.59%.indicating that the F-SiO₂/BPH-8 superhydrophobic coating can effectively improve the corrosion resistance of the metal substrate.（3）The F-SiO₂/BPH-8 superhydrophobic coating can be transformed into a super slippery surface by injecting dimethyl silicone oil.The wettability and stability of the sample surface are best when the viscosity of silicone oil is 100 m Pa·s.Compared with the superhydrophobic coating,the superslip surface has more comprehensive hydrophobicity and can stably repel complex liquids such as acids,bases,organic solvents and surfactants.Combining the superslip surface with a laser etched metal substrate can further improve its corrosion resistance properties.The electrochemical test results show that compared with the superhydrophobic sample,the corrosion potential of the superslip sample increased from-238.7 m V to-218.6 m V.The corrosion current density underwent a substantial decrease from 8.38*10^-7 A/cm² to 6.02*10^-9A/cm²,another two orders of magnitude,and the corrosion resistance efficiency reached 99.98%.The above results indicate that super-slick surface can provide more adequate protection to the metal substrate.