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Orderednanomaterial——Self-assemblyLidanLidan,SchoolofChemistry&ChemicalEngineeringIntroductionSelf-assemblyisawidespreadphenomenoninnature.Biologicalcells,animalbones,shells,pearls,naturalmineralzeoliteandsoonareallnano-structredmaterialsthroughself-assemblytechnical.2calcareousstructureinthebodyofplanktonLidan,SchoolofChemistry&ChemicalEngineeringIntroduction3Wehaveusedself-assemblytofabricatematerialsforonly20years.Itiswidelybelievedthatself-assemblyisaprocess,inwhichatoms,molecules,particles,andotherunitscombinetogethertogeneratenanomaterialsspontaneouslydrivenbylowestenergyprincipleinthesuitablephysicalandchemicalconditions.Inthisprocess,themostimportantdrivingforceistheinteractionforceamongthestructuralunits,likehydrogenbond,VanderWaalsforce,electrostaticinteraction,hydrophilic-hydrophobicinteractionandsoon.Lidan,SchoolofChemistry&ChemicalEngineeringContentsself-assemblyofVanderWaalsforceself-assemblyofelectrostaticattractionself-assemblyoftemplatemethodself-assemblyofvaporphasecatalyticself-assemblyofsurfacetensionandcapillaryforceself-assemblyofmicroemulsionself-assemblyoforientedattachment4Lidan,SchoolofChemistry&ChemicalEngineering5Thestructureofsurfactant:thereisatleastonehydrophilicgroupinthehead,alongwithonehydrophobicgroupinthetail.Itcanbeadsorbedonthesurfaceorinterfacetodecreaseitssurfaceenergyinlowconcentration.schematicofsurfactantSelf-assemblyofmicroemulsionStructureofsurfactantLidan,SchoolofChemistry&ChemicalEngineering6Surfactanthastwostates.Firstisdispersedstate,whichisalsocalledasionizationstate.Thesecondiscondensedstate,inwhichmicellewillbegenerated.Theshapeofmicelleisvariousduetocompositionofsolution.Itmaylooklikespherical,rod-like,hexagonal,cubic,flake,layerandsoon.Thesolutioncontainingorderedmicellarstructurecanchangeintogelafterdehydration.Then,orderedmesoporousmaterialwillformafterdryingandcalcinationifitsstructuredoesnotcollapse.schematicofmicelleTheexistingstateofsurfactantandCMCLidan,SchoolofChemistry&ChemicalEngineering7Microemulsionmethodisalsoknownassurfactanttemplatemethod.Itmainlyutilizethispropertythatsurfactantcanaggregateinsolutiontoformmicelle(orreservemicelle),microemulsion(orreservemicroemulsion),liquidcrystalandvesica,whichhaveorderedmicrostructure.Mostofthesemicrostructuresareoftennano-sized.Itcannotonlyprovidespecialconditionandserveasmicro-reactor,butalsobeusedastemplate.Now,oxides,halides,chalcogenides,metals,polymers,inorganicsalts,andothernanostructuredmaterialshavebeenmadethroughsurfactanttemplatemethod(microemulsionmethod).Lidan,SchoolofChemistry&ChemicalEngineeringExample18Astableandhighlyactiveorderedmesoporouspolymer-basedacidcatalysthasbeenpreparedviaasimplesurfactanttemplatingapproachandoxidationtreatment.Theprecursors:low-polymerizedphenolicresinsand3-mercaptopropyltrimethoxysilaneThecouplingagent:TEOSThestructuredirectingagent:triblockcopolymerF127MainideaRawmaterialandfunctionLidan,SchoolofChemistry&ChemicalEngineering9ResultsTEMimagesTEMimagesofmesoporouspolymersmodifiedwithsulfonicacidgroupsshoworientedandhexagonallyarrangedpores,furtherconfirmingtheordered2-Dhexagonalmesostructure.Orderedmesostructurecanbeobservedinlargedomains,withoutdistinctdefects.Lidan,SchoolofChemistry&ChemicalEngineeringSelf-assemblyofVanderWaalsforce10Combiningtwonano-particleswithdifferentcomponentandsizetogethercanformcrystalstructurethroughVanderWaalsforce.Thedrivingforceintheself-assemblyprocessismaximizationofthestackingdensity,whichisconsistentwiththeessenceofVanderWaalsforce.Thisself-assemblymethodisgreatimportantindesigningnano-sizedmaterialwithnovelproperties.Lidan,SchoolofChemistry&ChemicalEngineeringExample211SEMimageofsuperlatticestructureassembledbybinarynanoparticlesLidan,SchoolofChemistry&ChemicalEngineeringself-assemblyofelectrostaticattraction12ProfessorWangZhonglinhasmadeinnovativeworkintheself-assemblyfieldinducedbyelectrostaticattraction.Lidan,SchoolofChemistry&ChemicalEngineering13Example3MainideaBycontrollinggrowthkinetics,growingnanobelt-basednovelstructureswhosesurfacesaredominatedbythepolarized±(0001)facetsissuccessful.ReasonsOwingtothepositiveandnegativeionicchargesonthezinc-andoxygen-terminated±(0001)surfaces,respectively,aspontaneouspolarizationisinducedacrossthenanobeltthickness.Thisphenomenonisattributedtoaconsequenceofminimizingthetotalenergycontributedbyspontaneouspolarizationandelasticity.Lidan,SchoolofChemistry&ChemicalEngineering14ResultsSEMimagesSEMimagesoftheas-synthesizedZnOnanobelts,showinghelicalnanostructure.Thetypicalwidthofthenanobeltis~30nm,andpitchdistanceisratheruniform.Thehelixesareright-handed.Lidan,SchoolofChemistry&ChemicalEngineering15Example4ReasonsExample4isanextensionofExample3Becauseas-preparedzincoxidenanorodesgrowalongtheorientationof(001)plane,thelatticearrangementcancausetwosideswithreversecharges.(001)planeenrichedwithzincatomshaspositivecharges,while(001)planeenrichedwithoxideatomshasnegativecharges.Inordertoreducethetotalenergyofthissystem,zincoxidewillfinallybeself-assembledintoflower-likeaggregates.Lidan,School