Fabrication And Properties Of Triazinedithiolsilane Nanofilm On Copper Surface

The corrosion protection of copper and its alloy is very important in daily life and industrial production.As for copper,organic corrosion inhibitors with single anti-corrosive functional group have been fully explored,which brings some limitations.This paper puts forward a new organic synthesis route,aiming to solve the above problems.In short,we can combine a variety of anti-corrosive functional groups into one compound and prepare the corresponding anti-corrosive structures via different techniques.For copper and its alloy,a novel kind of triazinedithiolsilane compound which was made up of protective triazinedithiol and silane groups was synthesized.In this thesis,one typical compound of triazinedithiolsilanes was utilized,named 6-?3-triethoxysilylpropyl?amino-1,3,5-triazine-2,4-dithiol monosodium salt?TESPA-TDT,abbreviated as TESPA?.On the one hand,different types of TESPA nanofilms were fabricated on copper surfaces via self-assembled technique and electrochemical deposition approaches.The corrosion resistance performances of those nanofilms were investigated?anti-corrosive properties?.On the other hand,composite nanofilms of TESPA and long-chain silanes were introduced onto roughed copper mesh and copper foam,giving rise to superwettable interfaces.The reuse stability and corrosion resistance to acid/alkali of the composite nanofilms were explored,accompanied with expanding their application fields.It is important to note that TESPA compounds do not appear for the first time,and Japanese scientists have synthesized it in 2006.However,this paper focuses on the “new organic synthesis route”,and TESPA is one of the innovations from the route.Self-assembled monolayer?SAM?of TESPA was prepared on copper surface,then TESPA thermal polymeric nanofilm was obtained by heating TESPA SAM.The as-prepared TESPA SAM protects copper from corroding with a efficiency of 76.73%,while TESPA polymeric nanofilm with a maximum efficiency of 95.59%.Equivalent circuit of the former is R?Q?R?Q?RG????and Gerischer impedance shows up as a typical characteristic.Equivalent circuit of the latter is R?Q?R?RQ???and Gerischer impedance disappers.Heating treatment makes two parts of TESPA SAM polymerize simultaneously.Silanol groups?-SiOH?crosslink through dehydration and condensation reations,giving rise to-SiOSi-structures.Dithiol groups unreacted with copper polymerize to the formation of disulfide bond?-SS-?.Based on the electrochemical polymerization principle of triazinethiol compounds,TESPA polymeric nanofilm was prepared via galvanostatic technique.Dithiol groups in TESPA monomers electrochemically polymerize and disulfide bonds?-SS-?develop accordingly.When the as-prepared TESPA polymeric nanofilm was hydrolyzed,alkoxy groups?-SiOCH₂CH₃?from TESPA monomers turn into be silanol groups?-SiOH?.The following heating makes dehydration and condensation reations happen,leading to-SiOSi-structures.The hydrolyzed TESPA polymeric nanofilm?without/with heating treatments?possess multifunctionality,capable of resisting corrosion and activating copper suface.The residual silanol groups?-SiOH?serve as an active platform for more chemical reactions.The anti-corrosive capability of the hydrolyzed TESPA polymeric nanofilm plus heating is better than that of the hydrolyzed TESPA polymeric nanofilm without heating due to formation of-SiOSi-structures.TESPA polymeric nanofilm developed directly by galvanostatic technique is controlled by electron charge transfer;the hydrolyzed TESPA polymeric nanofilm exhibits Warburg diffusion.On basis of the arrangement characteristics of TESPA SAM and TESPA polymeric nanofilm on copper surface?namely,dithiol groups chemically react with copper and protect the substrate at the bottom of the nanofilms;silanol groups serve as an active platform for more chemical reactions on top of the nanofilms?,two types of composite nanofilms were prepared by means of layer-by-layer approaches.One composite nanofilm was fabricated by applying TESPA and octyltriethoxysilane?OTES?which is harmless to metal surfaces.Another composite nanofilm was created by TESPA and octadecyltrichlorosilane?OTS?which is detrimental to metal surfaces.Although the alkyl chain of OTES?C8?is less than that of OTS?C18?,the protection efficiency of OTES-TESPA composite nanofilm is greater than that of OTS-TESPA.The reason why is that OTES reacts with TESPA developing non-corrosive by-product?alcohol?,and OTS reacts with TESPA yielding corrosive by-products?HCl?as well as impurity particles with high chlorine content.A combined etching method was applied to fabricate ideal micro-and nano-scale roughness on copper mesh.Introducing TESPA thermal polymeric nanofilm and OTS-TESPA composite nanofilm can endow roughed copper mesh with hydrophilic and superhydrophobic abilities.Superhydrophobic copper mesh can effectively separate oil/water mixtures?carbon tetrachloride,methylene chloride,toluene,n-hexane,octane-water?.After separation for 50 times,the seperatopm efficiency of the as-prepared superhydrophobic copper mesh exceeds 95%,and the corresponding mesh surface still maintains superhydrophobic property with contact angle of > 151 °.Hydrothermal oxidation method was utilized to creat micro-and nano-“bud-like” structures on copper foam.1H,1H,2H,2H-perfluorodecyltrimetho-xysilane silane?PFDTCS?with low surface energy was grafted onto copper foam surface with TESPA thermal polymeric nanofilm atop,giving rise to superhydrophobic copper foam.Superhydrophobic copper foam can effectively separate oil/water mixtures?toluene,octane,hexane,methylene chloride,carbon tetrachloride-water?.After separation for 50 times,the seperatopm efficiency of the as-prepared superhydrophobic copper mesh outweigh 98.3%,and the corresponding foam surface still maintains excellent superhydrophobic property with contact angle of > 160 °.The chemical stability and durability of superhydrophobic copper foam are better than those of superhydrophobic copper mesh because of fluorine atoms with low surface energy existed in PFDTCS.