Preparation And Properties Of Silicone-based Multifunctional Composite Coating

The global economic loss caused by metal corrosion is as high as trillion dollars every year.Hundreds of metals and even alloy materials have been exposed to corrosion in heavy industrial environments such as aerospace,aviation and national defense construction for a long time,resulting in serious corrosion.The development of high-corrosion and durable coating is crucial,among the many anticorrosion methods,the most ecomomical and simple method is to coat anticorrosive coating on the metal surface.In order to obtain high anticorrosion,durable anticorrosive,in this thesis,copolymer coatings and composites coaitngs were prepared by polydimethysiloxane(PDMS)modified polyurethane(PU)copolymer as matriax,then he microstructure of the coating was futher regulated by carbon materials with different morphologies as fillers to improve the anticorrosion and self-cleaning properties of the coating.The main content include:1.In order to overcome the short serive life of PDMS coatings due to physical damage,and improve the mechanical property of PDMS as well,in this paper,a kind of double dynamic covalent bond crosslinked network structure copolymer with imine bond and hydrogen bond between molecules was designed and synthesized.On the one hand,the double dynamic corrosking network structure gives the self-healing properties of the coating,on the other hand,the overall mechanical properties of the coating are regulated by the soft and hard segments of the copolymerization unit.Firstly,terephthalic rtfaldehyde modified PDMS(H₂N-PDMS-TA-NH₂)prepolymer was prepared by dehydration and condensation of aldehyde and amino groups.The result of IR spectra(FTIR)and NMR(¹HNMR)showed that the prepolymer reaction was successful and the amino groups at both ends of the molecular chain were retained.Next,prepolymer reacted with isophorone diisocyanate(IPDI)and chain extender to prepare organosilicon-PU copolymer(PDMS-TA-PUa).Then,brushing to obtain PDMS-TA-PUa coating.The influence of chain extender type and soft and hard segment ratio on coating performance was studied.PDMS-TA-PUa,with double dynamic covalent bond structure,when soft:hard segment ratio was 2:1,can completely healed cracks within 40?50 min with a fast self-healing behavior.WCA of PDMS-TA-PUa was 116.5±0.15°and SFE as low as6.1±2.11 m J/m².It meet the theory standard of self-cleaning,and the experimental results showed that the coating effectively resist the dirt such as coffee,ink and pigment.Moverover,the corrosion potential(E_corr)also indicates that the PDMS-TA-PUa-2 had certain anticorrosion.2.Carbon nanomaterials have many advantages,and enhance the properties of polymers,which also sui Table.for studying the effect of fillers on polymer coatings.Three kinds of carbon materials with different morphologies were prepared:tubular carbon nanotubes(MWCNTs),micro-flower carbon nanotubes composites alumina(MWCNTs/Al₂O₃)and flake titanium carbide(MXene).After mixed acidizing,there are a lot of-COOH and-OH groups.Synthesis of micro-flower like Al₂O₃ by hydrothermal-pyrolysis method.The hydrothermal conditional was 180?for 6h can obtain pure?-Al OOH precurosor with uniform size and clear structure.500?calcined for 2h to gain Al₂O₃.For the sake of prepare MWCNTs/Al₂O₃,KH-550 modified Al₂O₃ to enhance the binding force between Al₂O₃and MWCNTs.XRD,FTIR and SEM can prove the success compounding of MWCNTs/Al₂O₃.MXene is a new type 2D lamellar nanomaterials,HCl and Li F as raw,erosion of Al layer of raw material(Ti₃Al C₂)by in situ synthesis of HF.After peeling off,few layers or layers of nanomaterials were obtained,which had mant-OH,-F functional groups on the MXene sheet to make it easier to bind to other substances.3.Based on the above PDMS-TA-PUa copolymers,three kinds of carbonm materials with different morphologies were used as fillers,2.5wt%carbon materials/PDMS-TA-PUa composite were prepared to inverstigate different morphologies carbon material how to effect the mechanical properties,hydrophobicity,anticorrosive properties and self-cleaning properties of coatings.The experimental results shows that:(1)The storage modulus(G')was1.6×10⁴Pa,with the same mass fraction,the mechanical properties of 2.5 MWCNTs/PDMS coatings were improved the most(G'=4.0×10⁴Pa),2.5MXene/PDMS were next.(2)The difference in the reinforcing effect of fillers on coaitngs also results in the difference in the self-healing properties of composites.After the same healing time(24 h),2.5MXene/PDMS achieve better self-healing.(3)Composites coating formed a microstructure with different morphologies,which lead to different oil resistance,SFE and anticossion.CH₂I₂ CA of2.5MXene reached 93.7±3.61°,was 77°higher than PDMS-TA-PUa coating,SFE was13.92±0.30 m J/m²,was 2.69 m J/m² lower than PDMS-TA-PUa coating.Meanwhile,MXene sheets form a dense barrier layer in the coating,the corrosion current I_corr=5.54×10^-7A/cm²was one oreder of magnitude smaller than other two composite coatings,which can effectively block the erosion of H⁺.Moreover,composite coatings had better self-cleaning behaviors on pigment,milk,ink and so on.As a new two-dimensional nanomaterials,MXene plays an important role in the field of resin-based anticorrosive functional composites.