| As an important property of solid surfaces,wettability is determined by microstructure and chemical composition.On the basis of“lotus-like”molecular design principle,using inorganic-organic nano-hybrid materials on surface could effectively change the surface roughness,while the surface energy is reduced by low-surface-energy polymers.This layout has been popular in the biomimetic lotus leaf field on preparing superhydrophobic coatings for ages.Superhydrophobic coating not only owns hydrophobicity and oleophobicity,but also has self-cleaning,anti-fouling and anti-viscosity properties,which are of great significance to biology,engineering and industry fields.Fluoropolymer with extremely low-surface-energy was selected.The fluorinated segments were grafted?modified?into organosilicon polymer.And then the alkoxysilane of organosilicon polymer and tetraethoxysilane via hydrolysis and condensation were bonded onto the fluorosilicon polymers.As the result,a series of nano-hybrid fluorosilicon polymers were obtained.The corresponding transparent and?super?hydrophobic coatings were fabricated on glass.The main researches are listed as follows:1.Synthesis of a nano hybrid perfluoroalkyl oligosiloxane@SiO2 resins and their coating morphologies and performances?1?Transparent silica core was synthesized by hydrolysis and condensation of tetraethoxysilane?TEOS?with 1,2-bis?triethoxysilane?ethane?BTESE?,then the nano-hybrid perfluoroalkyl oligosiloxane resin?FSi@SiO2-1?was obtained by hydrolysis and condensation of silica core with 1H,2H,2H-perfluorooctyltriethoxysilane?PFOTES?.The FSi@SiO2-1 was diluted with hydrofluoroether?7200?to form a treatment solution.The treatment solution was sprayed onto glass,and a transparent hydrophobic coating with WCA=121.3°was obtained.The coating surface was smooth,and the transmittance could reach 91%.?2?Vinyl modified nano-silica sol bearing methacryloxypropyl trimethoxysilane?KH570?groups was synthesized,then a series of nano-hybrid perfluoroalkyl oligosiloxane resins?FSi@SiO2-2?were synthesized by hydrosilylation of modified nano-silica with fluoroalkylsilane?FPHMS?and1H,1H,2H-perfluoro-1-decene?PFDE?or 1H,1H,2H-perfluoro-1-octene?PFOE?.The FSi@SiO2-2 was diluted with hydrofluoroether?7200?to form a transparent treatment solution with a mass concentration of 0.5%.A transparent hydrophobic coating could build on rubber surface by spray method because resin has good tenacity.The WCA reached 125.8°,and the oil contact angle was 88.3°,and the transmittance was 90%.?3?Alkoxy modified fluoropolysiloxane was synthesized by hydrosilylation of trifluoropropyl vinyl silicone oil?FVSA?with trimethoxysilane?TMS?,then nano-hybrid perfluoroalkyl oligosiloxane resins?FSi@SiO2-3?with mean particles diameter of 150 nm were obtained by gradually hydrolysis and condensation of perfluoroalkyltrialoxy silane,as such PFOTES,with TEOS.FSi@SiO2-3 was coated by dipping method on glass.As the result,the transparent film root mean square roughness?Rq?was 0.346.and when the nanosphere surface was damaged,the fluorine chain inside could be exposed to the air again to maintain the durable hydrophobicity.Therefore,after sandpaper cycle abrasion test by loading 1 kg,the WCA still maintained around 115°.?4?By hydrosilylation of D4H with PFDE?or PFOE?and VTES,an intermediate cyclotetrasiloxane oligomer bearing perfluoroalkyl and trimethoxy silylethylene groups?FVPS?was synthesized.And then a perfluoro nano-SiO2hybrid polysiloxane oligomer resin?FSi@SiO2-4?was synthesized by hydrolysis and condensation of FVPS with TEOS.Composite coating was mixed with FSi@SiO2-4,MQ silicon resin and dibutyl tin diacetate.The MQ resin stabilized the nanoparticles and the curing effect was improved by catalyst,as the result,the WCA reached 150.3°.The coating not only had excellent transmittance,but also had good anti-fingerprint effect2.Synthesis of a C-OH containing perfluoropolysiloxane and its robust superhydrophobic coatingThe?-hydroxyethyl oxypropyl trimethoxysilane?TMS-OH?precursor was synthesized with ethylene glycol monallyl ether and TEOS via hydrosilylation with complex platinum as catalyst.Subsequently,referring to the st?ber method and under acidic conditions,C-OH containing perfluoropolysiloxane?FSi-OH?was obtained by hydrolysis and condensation of TMS-OH with PFOTS and TEOS.FT-IR and 1H-NMR indicated the FSi-OH resin contains a large number of C-OH groups which crosslinked with the curing agent isocyanate to form a film,and the abrasion fastness and chemical stability of the coating were improved.FESEM,AFM,laser particle size analyzer and contact angle results showed that when the particles size were 200-300 nm,dispersibility of nano-particles was good,and film showed micro-scale multi-roughness.The average roughness?Ra?of the film was2.967 nm,and the root mean square roughness?Rq?was 4.233 nm.Application results showed the FSi-OH coating could endow excellent superhydrophobicity with WCA of 151.1°.From the XPS results,it can be concluded that the cotaing surface had C,O,F and Si elements,and the contents of each element were 32.96%,17.79%,37.83%and 11.42%,respectively.Obviously,the fluorocarbon segments in PFOTS had the orientation of the surface,thus the coating surface contained a large amount of fluorine,and the surface energy of the FSi-OH treated coating was reduced.Subsequently,with steel wool under 500 g weight,and after 400 cycles abrasion;or after the 4 hours water dropping test,the coating still maintained superhydrophobicity.In addition,FSi-OH coating could withstand corrosive liquids and can be used in harsh environments.Finally,superhydrophobic mechanism of FSi-OH coating on the glass surface had been explained by the Cassie model showed that the proportion of air at the composite contact interface was 83%,which indicated that the treated glass surface have“lotus-like”structure.The air in the micro rough structure allowed the water droplets stand on the top of the film,so the FSi-OH coating had excellent superhydrophobicity.3.PreparationandcharacterizationofPOSShybrid poly?perfluoropolyether?methacrylate copolymer and its superhydrophobic coating performanceThe basic design was a random polymer with three variable monomer classes via a free-radical solution polymerization.The first monomer class were oleophilic alkyl?meth?-acrylates;specifically,methyl?meth?acrylate?MMA?and methacrylisobutyl POSS?MAPOSS?.The second monomer class was the hydrophobic,oleophobicandenvironmentalfriendly poly?perfluoropolyether?methacrylate?PFPEM?macromonomer with Mn=1700and 1H,1H,2H,2H-perfluorooctyl acrylate?C6F?.The third monomer class was reactive monomers that contained curable functional groups:Hydroxypropyl acrylate?HPA?and KH570.PFPEM and perfluorohexyl group had strong mutex with oleophilic acrylates,and they were incompatible which led to micro-phase separating morphologies.In this hierarchical micro-nano roughness structure,the relatively light hydrophobic and high hardness POSS was mostly buried below the film surface to improve the coating robust.Furthermore,the coating hierarchical micro-nano roughness also had positive effects on micro roughness,the static CA and mechanical durability of coatings.Consequently,the film root mean square roughness was 15.2 nm.Moreover,with the MAPOSS content increasing,the coating roughness bacome higher.When MAPOSS dosage was 25 wt%,the grafting rate of MAPOSS was 6.94%,and the PPPEM-POSS coating had optimal performances which WCA was 152.3°,and the coating surface tension was 15.6mN/m.PFPEM-POSS coatings not only had good hydrophobicity,but also had good mechanical properties.After 5,000 times of 500 g weight-bearing cotton abrasion,the contact angle of the coating decreased by 0.99%.Furthermore,when the different pH drops on the coating,the contact angle changed a little,indicating that the PFPEM-POSS coating can withstand corrosive liquids and can be used in harsh environments. |
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