Preparation And Properties Of Organosilicon/metal Hydrophobic Composite Coatings

The preparation method of superhydrophobic coatings involves complicated multi-steps and harsh conditions,which requires special instruments and equipment.So it is difficult to be industrialized.Monomers or hydrophobic polymers containing fluorine atoms in the structureare are widely used in low surface energy modifiers.It may cause pollution of water,soil and air,corrosion and other problems,and is not conducive to people’s health.At the same time,the superhydrophobic coatings has the disadvantages of low hardness,poor durability,poor light transmittance,etc.,which seriously restricts its application in industry and life.Therefore,choosing environment-friendly monomers as raw materials to prepare hydrophobic coatings with stable surface structure and superior mechanical properties is an important problem that needs to be solved urgently.In this thesis,the micelles were prepared by in-situ hydrolysis and polymerization usingγ-glycidoxypropyltrimethoxysilane（KH560）,N-（β-aminoethyl）-γ-aminopropyltrimethoxysilane（KH792）,tetraethyl orthosilicate（TEOS）and zirconium acetate（ZrAc）as monomers and octyltrimethoxysilane（OTMS）was used as low surface energy modified material.A variety of organosilicone and organosilicone/zirconium hydrophobic coatings were prepared by cross-linking with in-situ micelles to achieve surface coating and modification of octyl low surface energy chains on the surface of micelles.The influence of substrate etching on the hydrophobic properties of the coating was discussed.The Organosilicon/NFC and Organosilicon/Zirconium/NFC composite hydrophobic coatings were prepared by using nano cellulose（NFC）to construct micro rough structure.The main functional groups in micelles and coatings were analyzed by FTIR,the surface element composition of the coating was detected by XPS,the micro morphology of the coating was characterized by SEM and AFM,the water contact angle,hardness and transmittance of the coating were tested,the formation mechanism of sol and hydrophobic coating was proposed.（1）Preparation and properties of a variety of organosilicone copolymer hydrophobic coatings with high hardness.KH560-KH792-OTMS copolymerization coating was prepared with KH560-KH792 and OTMS.FTIR showed that KH560-KH792 formed micelles in situ after addition,hydrolysis and polymerization,and then hydrolyzed and copolymerized with OTMS.On the surface of the micelles,the octyl hydrophobic group was grafted to prepare sol,and organosilicone copolymerization coating was formed on the glass.The test results showed that KH560-KH792-OTMS coating hardness reached 5H after curing at room temperature,water contact angle was 101.13°,the dense high molecular weight carbon chain leads to light transmittance was less than 90%,lower than the glass.TEOS-OTMS copolymerization coating was prepared with TEOS and OTMS.The FTIR showed that TEOS pre-hydrolyzed and polymerized,then hydrolyzed and grafted with OTMS to form TEOS-OTMS micelles.When TEOS was hydrolyzed for 4 h and OTMS was added for 20 min,the water contact angle of organosilicone coating on the smooth glass substrate reached 124.01°,and the hardness reached 6H.The nanostructure of the coating increased the light transmittance of the coating to 94.86%,which is 2.07%higher than that of the glass.The water contact angle of TEOS-OTMS coating reached 160.08°and arithmetic average roughnessr eached 100 nm,which was superhydrophobic.XPS showed that the grafting of OTMS changed the hydrophobic groups of KH560-KH792 and TEOS coatings towarded the self-assembled surface reconstruction phenomenon,and improved the structural stability of the hydrophobic coatings.（2）The formation mechanism of organosilicon/zirconium sol and the properties of coating were studied.ZrAc-OTMS sol and coating were prepared by hydrolysis polymerization in the system of alcohol and water with ZrAc and OTMS as precursors.The effects of ZrAc pre-hydrolysis polymerization time and ZrAc-OTMS co-hydrolysis time on the hydrophobicity of the coating were studied.The experimental results showed that the coating prepared by single ZrAc sol was compact and uniform,the hardness reached 5H,the water contact angle was only 67.36°,and the visible light transmittance was reduced by 1.1%compared with the glass.When ZrAc was pre-hydrolyzed and polymerized for 1 h and then hydrolyzed by OTMS for 50 min,the water contact angle of the coating was 132.01°and the hardness was 3H.The average light transmittance was 93.72%,and the maximum light transmittance was 95.30%,which was 2.51%higher than that of the glass.FTIR results showed that ZrAc was hydrolyzed to form Zr-OH in the system of alcohol and water and polymerized in to-O-Zr-O-micelles.Si-OH generated by the hydrolysis of OTMS was grafted and polymerized with Zr-OH in ZrAc micelles,and the low surface energy octyl chain was connected on the surface of ZrAc micelles to form ZrAc-OTMS micelles.SEM showed that the addition of OTMS changes the compactness of single ZrAc coating,and the ZrAc-OTMS coating prepared on the glass are interconnected in porous network structure.（3）Preparation and properties of nano cellulose/silicone/zirconium composite coating.Nanocellulose was used to construct the rough microstructure on the glass,and the hydrophobicity and wear resistance of the coating were detected.The microstructure of the coating was characterized by SEM.NFC-TEOS-OTMS was prepared by layered method.SEM results showed that the nano-cellulose layered coating on the glass was conducive to the accumulation of Si O₂in the TEOS-OTMS hydrophobic coating,reduced the distance between the protuberances and the contact area between the droplets and the matrix,and the water contact angle increased from 124.01°to 136.57°.The coating lost its hydrophobicity after being rubbed by 1000 mesh sandpaper with a load of 100g for 7 times.The water contact angle increased from 124.01°to 136.57°and nano cellulose coated with stearic acid was dispersed into ZrAc-OTMS system to prepare sol,and M-NFC-ZrAc-OTMS composite coating was prepared.SEM results showed that the presence of M-NFC in the system hindered the polymerization of ZrAc and OTMS,increased the pore size of the coating,increased the air area in the groove,and improved the hydrophobicity of the coating.When the addition of M-NFC was 3.0%,the water contact angle of the coating could reach 140.23°.After 15 times of friction with 1000 mesh sandpaper loaded with 100 g,the hydrophobic property of the coating was lost.（4）Effect of coating microstructure on hydrophobicity of coatings.The microstructure of the coating is an important factor to improve the hydrophobicity of the coating and a necessary condition to obtain superhydrophobic coating.SEM results showed that the coating of KH560-KH792-OTMS was uniform and dense,and the maximum hydrophobic angle was101.13°;the microstructure of TEOS-OTMS coating was formed on the glass surface with the size of 35～55 nm,and the maximum hydrophobic angle was 124.01°.After 14 h etching in etching solution,the 16.75 nm microbulges were formed,which promoted the entangling and aggregation of TEOS-OTMS.The Si O₂polymer on the glass surface kept agglomerating and stacking on the coating surface,forming a cluster microstructure with the size of 594.77 nm.AFM results showed that after etching,the roughness of TEOS-OTMS coating was significantly improved,the root mean square roughness（Rq）was 125 nm,the arithmetical mean roughness（Ra）was 100 nm,and the hydrophobic angle of the coating reached 160.08°,which was superhydrophobic.