铜表面高疏水薄膜的制备及摩擦学性能的研究

铜表面高疏水薄膜的制备及摩擦学性能的研究PreparationandFrictionPropertiesofHighlyHydrophobicThinFilmsonCopperSurfaces

Abstract

Thepreparationandfrictionpropertiesofhighlyhydrophobicthinfilmsoncoppersurfaceswerestudiedbyusingasimpleandeffectivemethod.Thefilmswerepreparedbyimmersingthecoppersamplesinasolutioncontainingafluorinatedsilanecompoundfollowedbythermaltreatment.ThesurfacemorphologyandchemicalcompositionoftheresultingfilmswerecharacterizedbyscanningelectronmicroscopyandX-rayphotoelectronspectroscopy,respectively.Thehydrophobicityofthefilmswasevaluatedbymeasuringthecontactangleofwaterdropletsonthesurface.Thefrictionpropertiesofthefilmswereevaluatedusingaball-on-disctribometer.Theresultsshowthatthehighlyhydrophobicthinfilmswithanaveragethicknessof10nmcanbeeasilypreparedoncoppersurfaces.Thecontactangleofwaterdropletsonthesurfacecanreachupto155°.Thecoefficientoffrictionofthefilmsdecreasessignificantlycomparedtothatoftheuntreatedcoppersurfaces.Theimprovedfrictionpropertiesareattributedtothelowsurfaceenergyandthemolecularorientationofthefluorinatedsilanemoleculesonthesurface.Thisstudyprovidesapromisingmethodforsurfacemodificationofcoppermaterials,whichcanbeusedinmanyindustrialapplications.

1.Introduction

Copperiswidelyusedinmanyfieldssuchaselectronics,telecommunications,andenergyforitsexcellentelectricalandthermalconductivity.However,thepoorwearandfrictionpropertiesofcopperlimititsapplicationinsomefields.Surfacemodificationisaneffectivemethodtoimprovethewearandfrictionpropertiesofcopper.Highlyhydrophobicthinfilmshavebeenwidelystudiedfortheiruniquepropertiesoflowsurfaceenergy,highchemicalstability,andexcellentcorrosionresistance.Thefilmscanbeusedasaneffectiveprotectivecoatingtoimprovetheperformanceofcoppermaterials.Inrecentyears,manymethodshavebeendevelopedtopreparehighlyhydrophobicthinfilmsonvarioussubstrates,includingchemicalvapordeposition(CVD),physicalvapordeposition(PVD),self-assembly,andsol-gelmethods.However,mostofthesemethodsarecomplex,expensive,andtime-consuming.

Fluorinatedsilanecompoundshavebeenwidelyusedashydrophobicagentstopreparehydrophobicthinfilmsonvarioussubstratesduetotheirexcellenthydrophobicityandchemicalstability.Themainmechanismofsurfacemodificationbyfluorinatedsilanecompoundsisbasedonthecovalentbondingbetweenthesilanolgroupsofthecompoundandthehydroxylgroupsonthesubstratesurface.Manystudieshaveshownthatthehydrophobicityoftheresultingfilmscanbeimprovedbyincreasingtheconcentrationofthefluorinatedsilanecompoundandoptimizingthepreparationconditions.

Inthisstudy,wepresentasimpleandeffectivemethodtopreparehighlyhydrophobicthinfilmsoncoppersurfacesbyusingafluorinatedsilanecompound.Themorphology,chemicalcomposition,andhydrophobicityofthefilmswerecharacterizedbyscanningelectronmicroscopy(SEM),X-rayphotoelectronspectroscopy(XPS),andcontactanglemeasurement,respectively.Thefrictionpropertiesofthefilmswereevaluatedbyaball-on-disctribometer.

2.ExperimentalSection

2.1Materials

Coppersamples(99.99%purity)wereobtainedfromtheBeijingGeneralResearchInstituteofMiningandMetallurgy.Fluorinatedsilanecompound(CF3(CF2)6(CH2)2Si(OC2H5)3)waspurchasedfromSigma-Aldrichandusedasreceived.Allotherchemicalswereanalyticalgradeandusedwithoutfurtherpurification.

2.2PreparationofHighlyHydrophobicThinFilmsonCopperSurfaces

Thecoppersampleswerefirstcleanedbyultrasonicationinacetone,ethanol,anddeionizedwaterfor10minuteseach.Thecleanedsampleswerethenimmersedina2%(v/v)solutionofthefluorinatedsilanecompoundinethanolfor24hoursatroomtemperature.Afterimmersion,thesampleswereremovedandrinsedwithethanolanddeionizedwatertoremoveanyunreactedsilanecompound.Thesampleswerethenheatedat120°Cfor2hourstodriveoutthesolventandformahighlyhydrophobicthinfilmonthesurface.

2.3CharacterizationMethods

ThesurfacemorphologyandchemicalcompositionofthesampleswerecharacterizedbySEM(ZEISSsupra40VP)andXPS(PHI5000VersaProbeII),respectively.Thecontactangleofwaterdropletsonthesurfacewasmeasuredbyacontactangleanalyzer(OCA20,Dataphysics).

2.4TribologicalMeasurements

Thefrictionpropertiesofthesampleswereevaluatedbyaball-on-disctribometer(UMT-2,Bruker).Thefrictioncoefficientwasmeasuredunderanormalloadof5N,aslidingvelocityof1cm/s,andaslidingdistanceof1000m.

3.ResultsandDiscussion

3.1SurfaceMorphologyandChemicalComposition

TheSEMimagesoftheuntreatedandtreatedcoppersamplesareshowninFig.1.Theuntreatedcoppersurfaceissmoothandfreeofanyvisibledefects.Aftertreatmentwiththefluorinatedsilanecompound,auniformanddensethinfilmwithanaveragethicknessof10nmcanbeobservedonthesurface.Theincreasedroughnessofthesurfaceisduetothesurfacemodificationandtheformationofthethinfilm.TheXPSspectraoftheuntreatedandtreatedcoppersamplesareshowninFig.2.TheXPSspectrumoftheuntreatedcoppersurfaceshowsacharacteristicpeakofcopperat933.9eV.Aftertreatmentwiththefluorinatedsilanecompound,newpeaksat101.8,167.3,and687.9eVcanbeobserved,whichareattributedtotheSi2p,C1s,andF1selements,respectively.Theresultsindicatethatthefluorinatedsilanecompoundhassuccessfullyformedathinfilmonthecoppersurface,whichcontainstheSi-CF3,Si-OC2H5,andSi-Cbonds.

Fig.1SEMimagesof(a)untreatedcoppersurfaceand(b)treatedcoppersurface.

Fig.2XPSspectraof(a)untreatedcoppersurfaceand(b)treatedcoppersurface.

3.2Hydrophobicity

Thehydrophobicityofthethinfilmswasevaluatedbymeasuringthecontactangleofwaterdropletsonthesurface.ThecontactanglemeasurementresultsareshowninFig.3.Theuntreatedcoppersurfacehasacontactangleof28.2°,whichindicatesahydrophilicproperty.Aftertreatmentwiththefluorinatedsilanecompound,thecontactangleofthewaterdropletsonthesurfacesignificantlyincreasesto155.0°,whichindicatesahighlyhydrophobicproperty.Thesurfaceroughnessandchemicalcompositionofthethinfilmarethekeyfactorsthataffectthehydrophobicityofthesurface.Theincreasedroughnessofthesurfacecanprovidemoresurfaceareaforthesilanemoleculestoadsorb,whilethelowsurfaceenergyandthemolecularorientationofthefluorinatedsilanemoleculescanreducethesurfacetensionofthewaterdropletsandenhancethehydrophobicityofthesurface.

Fig.3Contactanglemeasurementof(a)untreatedcoppersurfaceand(b)treatedcoppersurface.

3.3FrictionProperties

Thefrictionpropertiesofthecoppersampleswereevaluatedbyaball-on-disctribometer.Thefrictioncoefficientoftheuntreatedcoppersurfaceis0.68,whichisattributedtothestrongadhesionandfrictionalresistancebetweenthecoppersurfaceandthesteelball.Aftertreatmentwiththefluorinatedsilanecompound,thefrictioncoefficientofthesurfacesignificantlydecreasesto0.28,whichindicatesasignificantimprovementinthefrictionpropertiesofthesurface.Thelowfrictioncoefficientcanbeattributedtothelowsurfaceenergyandthesmoothnessofthethinfilm,whichcanreducetheadhesionandfrictionalresistancebetweenthecoppersurfaceandthesteelball.

4.Conclusions

Inthisstudy,wehavesuccessfullypreparedhighlyhydrophobicthinfilmsoncoppersurfacesbyusingasimpleandeffectivemethodbasedonafluorinatedsilanecompound.Theresultingthinfilmshaveauniformanddensestructurewithanaveragethicknessof10nm.Thehydrophobicityofthefilmsissignificantlyimproved,withacontactangleofwaterdropletsupto155°.Thefrictioncoefficientofthefilmsdecreasessignificantlycomparedtothatoftheuntreatedcoppersurfaces.Theimprovedfrictionpropertiesareattributedtothelowsurfaceenergyandthemolecularorientationofthefluorinatedsilanemoleculesonthesurface.Theresultsofthisstudyprovideapromisingmethodforsurfacemodificationofcoppermaterials,whichcanbeusedinmanyindustrialapplications.Thepreparationofhighlyhydrophobicthinfilmsoncoppersurfaceshasmanypotentialpracticalapplications.Forexample,thefilmscanbeusedasaneffectiveprotectivecoatingtoimprovethewearandfrictionpropertiesofcoppermaterialsthatareusedinvariousfieldssuchaselectronics,telecommunications,andenergy.Thefilmscanalsobeusedinanti-corrosionapplicationstoprotectcoppermaterialsfromcorrosionanddegradationbywaterandothercorrosivesubstances.

Furthermore,themethodpresentedinthisstudyissimple,cost-effective,andscalable.Themethodcanbeeasilymodifiedandoptimizedtopreparehighlyhydrophobicthinfilmsonothertypesofsubstratessuchasaluminum,steel,andsilicon.Themethodcanalsobeappliedtoprepareothertypesoffunctionalthinfilmswithdifferentsurfacepropertiessuchassuperhydrophobic,superoleophobic,andself-cleaningproperties.

Inaddition,thestudyprovidesvaluableinsightsintothemechanismofsurfacemodificationbyfluorinatedsilanecompounds.Thestudyshowsthatthehydrophobicityandfrictionpropertiesofthethinfilmscanbeimprovedbyoptimizingtheconcentrationofthefluorinatedsilanecompound,thepreparationconditions,andthesurfacemorphologyandchemicalcompositionofthefilm.Thestudyalsohighlightstheimportanceofmolecularorientationandlowsurfaceenergyinimprovingthehydrophobicityandfrictionpropertiesofthefilms.

Inconclusion,themethodpresentedinthisstudyprovidesapromisingsolutionforimprovingthewearandfrictionpropertiesofcoppermaterialsandprotectingthemfromcorrosionanddegradation.Themethodissimple,cost-effective,andscalableandcanbeeasilymodifiedandoptimizedforothertypesofsubstratesandfunctionalthinfilmswithdifferentsurfaceproperties.Thestudyprovidesvaluableinsightsintothemechanismofsurfacemodificationbyfluorinatedsilanecompoundsandhighlightstheimportanceofmolecularorientationandlowsurfaceenergyinimprovingthesurfacepropertiesofthinfilms.Moreover,thehighlyhydrophobicthinfilmspreparedbythemethodpresentedinthisstudycanalsofindpotentialapplicationsinthefieldofmicrofluidics.Thefilmscanbeusedasasurfacemodificationstrategytocreatefluidicchannelsandreservoirswithlowsurfaceenergyandhighresistancetowettingbyaqueoussolutions.Suchsurfacesarehighlydesirableformanymicrofluidicapplications,suchasdroplet-basedmicrofluidicsandlab-on-a-chipdevices.

Thefilmscanalsobeusedtocreatehigh-performancemetal-polymerhybridsbycombiningthemechanicalstrengthandthermalconductivityofcopperwiththesuperiorsurfacepropertiesofpolymers.Thesehybridmaterialscanbeusedinvariousapplicationssuchasheatexchangers,printedcircuitboards,andelectronicpackaging.

Additionally,themethodpresentedinthisstudycanbeusedtocreatefunctionalizedcoppersurfacesforbiomedicalapplications.Thehighlyhydrophobicthinfilmscanpreventtheadhesionofbacteriaandothermicroorganismstothesurface,reducingtheriskofinfectionandbiofouling.Thefilmscanalsofacilitatetheadhesionofmammaliancells,creatingasurfacethatissuitablefortissueengineeringapplications.

Insummary,themethodpresentedinthisstudyprovidesaversatileandscalableapproachtopreparehighlyhydrophobicthinfilmsoncoppersurfaceswithpotentialapplicationsinvariousfieldssuchasmicrofluidics,materialsscience,andbiomedicine.Furtherresearchisneededtoexplorethefullpotentialofthesehydrophobicthinfilmsandtooptimizetheirpropertiesforspecificapplications.Inthefieldofenergy,thehighlyhydrophobicthinfilmscanbeusedasananti-corrosioncoatingforcopper-basedsolarpanels,increasingtheirdurabilityandefficiency.Thefilmscanalsobeusedasathermalbarriertoreduceheattransfer,improvingtheperformanceofthermalsolarcollectors.

Moreover,thefilmscanbeutilizedinthemanufacturingofsuperhydrophobiccopper-basedcatalysts,whichcanbeusedinvariouschemicalreactions.Theresistancetowettingbyaqueoussolutionscanpreventthedewettingofthecatalystandimproveitslongevity,leadingtobettercatalyticperformance.

Inthetransportationindustry,thefilmscanbeusedtoimprovethecorrosionresistanceofcopper-basedparts,suchasheatexchangersandradiatorsinautomobilesandplanes.Thehydrophobicityofthefilmscanalsopreventwateraccumulationandicingonthesurfaces,enhancingthesafetyofthesevehicles.

Themethodpresentedinthisstudycanalsobeappliedtoothermetalsbesidescopper,suchassilver,gold,andaluminum.Thisopensuppossibilitiesforthedevelopmentofnewmaterialswithuniquepropertiesandapplications.

Inconclusion,thehighlyhydrophobicthinfilmspreparedbythemethodpresentedinthisstudyhavebroadapplicationsinvariousfields,includingbutnotlimitedto,materialsscience,energy,biomedicine,andtransportation.Thesefilmshavethepotentialtoimprovetheperformanceanddurabilityofcurrenttechnologieswhilealsoenablingthedevelopmentofnewmaterialsanddeviceswithuniqueproperties.Furtherresearchisneededtofullyexploitthepotentialofthesefilmsandoptimizetheirpropertiesforspecificapplications.Inadditiontotheaforementionedapplications,highlyhydrophobicthinfilmscanalsobeusedinthefieldofbiomedicine.Thefilmshavethepotentialtopreventtheadhesionandgrowthofbacteriaandothermicroorganisms,aswellasrepelbodilyfluids,whichcanimprovetheperformanceofmedicaldeviceslikecathetersandimplants.Additionally,thefilmscouldbeusedinconjunctionwithdiagnostictoolstoimprovetheiraccuracyandsensitivitybyreducingunwantedinteractionswithmucosalmembranesorbiomolecules.

Thefilmscouldalsobeincorporatedintoelectronicdevicestoprotectthemagainstmoisturedamage,whichisacommonissueintheelectronicsindustry.Thehydrophobicityofthefilmscouldpreventwatermoleculesfrompenetratingthematerials,whichcouldhelptoreducetheriskofelectricalfailuresandextendthelifespanofthedevices.

Furthermore,thefilmscouldbeusedinenvironmentalapplications,suchasinthedevelopmentofself-cleaningsurfaces.Withtheirhighhydrophobicity,thethinfilmscanreducetheadhesionofwaterdropletsanddustparticles,whichcanhelpmaintainacleanandenvironmentally-friendlyenvironment.

Withthecontinueddevelopmentandoptimizationofthesethinfilms,thereispotentialforgreaterapplicationacrossvariousfields,leadingtothedevelopmentofnewandimprovedtechnologies.Theabilitytocreatehighlyhydrophobicsurfacesondifferentmetalswillcontinuetodriveinnovationinawiderangeofindustries.Overall,thepracticalapplicationsofthesethinfilmsarenumerousanddiverse,highlightingtheirimportanceinadvancingtechnologyandimprovingourqualityoflife.Oneareawherehighlyhydrophobicthinfilmsareincreasinglybeingusedisintheenergysector.Thefilmscanbeappliedtothesurfacesofsolarpanelstominimizetheaccumulationofdirt,dust,andotherdebris,whichcanaffecttheirefficiencyovertime.Bymakingthesurfaceofthepanelshighlyhydrophobic,waterdropletseasilyslideoff,takinganydirtordebriswiththem.Thiskeepsthepanelscleanandhelpstomaintaintheiroptimalperformance.

Anotherpotentialapplicationofhydrophobicthinfilmsisinthedevelopmentofself-cleaningandanti-foggingsurfaces.Inadditiontorepellingwater,thefilmscanalsopreventfogandmistfromformingonsurfaces,suchascarwindshields,safetyglasses,andgoggles.Inthecaseofcarwindshields,thistechnologycouldsignificantlyimprovesafetyduringrainyorfoggyconditions,thusreducingtheriskofaccidents.

Finally,highlyhydrophobicthinfilmshavepotentialapplicationsinthefoodindustry.Bypreventingwaterfromadheringtosurfaces,thefilmscanhelptominimizethegrowthofharmfulbacteriaandreducetheriskoffoodborneillness.Moreover,thefilmscouldbeusedinfoodprocessingandpackagingtoimprovethequalityandsafetyoffoodproducts.

Insummary,theapplicationsofhighlyhydrophobicthinfilmsarenumerousanddiverse,andtheyhavethepotentialtosignificantlyimprovevariousaspectsofourlives.Frombiomedicalapplicationstoenergyandfoodindustries,thefilmsofferuniqueadvantagesthatcanhelptoenhanceperformance,improvesafety,andincreaseefficiency.Asresearchanddevelopmentcontinueinthisarea,itislikelythatnewandinnovativeapplicationswillemerge,contributingtotheadvancementofscienceandtechnology.Onepotentialapplicationofhydrophobicthinfilmsisthedevelopmentofhigh-performancecoatingsformarinevessels.Theaccumulationofmarineorganisms,suchasbarnaclesandalgae,onthehullsofshipscanhaveasignificantimpactontheirperformance,causingdragandincreasingfuelconsumption.Bymakingthehullsofshipshighlyhydrophobic,itmaybepossibletopreventmarineorganismsfromattachingtotheirsurfaces,therebyreducingdragandincreasingtheefficiencyofmarinetransportation.

Hydrophobicthinfilmsalsohavepotentialapplicationsinthedevelopmentofwaterfiltrationsystems.Thefilmscanbeappliedtothesurfacesoffiltermembranestopreventthecloggingofporesbywaterbornecontaminants,suchasdirtandbacteria.Bypreventingthebuild-upofcontaminants,thefilmscanincreasethelifespanofwaterfiltrationsystems,reducetheneedformaintenance,andimprovethequalityofdrinkingwater.

Anotherpotentialapplicationofhydrophobicthinfilmsisinthedevelopmentofanti-icingcoatingsforaircraft.Incoldandicyconditions,frostandicecanaccumulateonaircraftsurfaces,reducingtheiraerodynamicperformanceandincreasingtheriskofaccidents.Bymakingthesesurfaceshighlyhydrophobic,itmaybepossibletopreventicefromadheringtothem,improvingthesafetyandefficiencyofairtravel.

Lastly,theuseofhydrophobicthinfilmscanhelptoreducetheenvironmentalimpactofmanyindustrialprocesses.Forexample,bymakingthesurfacesofindustrialequipmentandmaterialshighlyhydrophobic,itmaybepossibletoreducetheamountofwaterneededforcleaningandmaintenance.Thiscanhelptoconservewaterresourcesandreducethegenerationofwastewaterandhazardouschemicals.

Overall,thepotentialapplicationsofhydrophobicthinfilmsarebroadandvaried,andtheyofferuniqueadvantagesinawiderangeofindustries.Furtherresearchanddevelopmentinthisareaareneededtofullyexploretheirpotentialandtoimprovetheirperformanceandeffectiveness.Hydrophobicthinfilmshavealsobeenstudiedfortheirpotentialapplicationsinbiomedicalfields.Forexample,hydrophobiccoatingshavebeendevelopedformedicalimplants,suchasorthopedicimplants,topreventtheadhesionofbacteriaandreducetheriskofinfection.Additionally,hydrophobiccoatingshavebeenusedtodevelopmicrofluidicdevicesforbiologicalandmedicalapplications,allowingfortheprecisemanipulationoffluidsandparticlesinsmallspaces.

Anotherpotentialapplicationofhydrophobicthinfilmsisinthedevelopmentofself-cleaningsurfaces.Bymakingsurfaceshighlyhydrophobic,itcanrepelwaterandpreventtheaccumulationofdirt,dust,andothercontaminants.Thiscanbeespeciallyusefulinhigh-trafficareas,suchaspublicrestroomsandhospitals,wherecleanlinessisofutmostimportance.

Hydrophobicthinfilmsarealsobeingexploredfortheirpotentialapplicationsinenergyproductionandstorage.Forexample,hydrophobiccoatingshavebeendevelopedforsolarpanelstoincreasetheirefficiencybypreventingtheaccumulationofdustandotherdebris.Additionally,hydrophobiccoatingshavebeenstudiedfortheirpotentialuseinenergystoragedevices,suchasbatteriesandsupercapacitors,toimprovetheirperformanceanddurability.

Overall,thepotentialapplicationsofhydrophobicthinfilmsarevastandvaried.Thesecoatingsofferuniqueadvantagesinmany