嵌段共聚物自组装纳米薄膜

嵌段共聚物自组装纳米薄膜第1页/共33页MainReference第2页/共33页OutlineIntroductionExperimentalPartResultsandDiscussionConclusionsInnovationsandProblemsReferences第3页/共33页1.

IntroductionAmphiphilicblockcopolymers(BCs)couldcontrolmaterialinterfaces.The3DconstructionisdirectedbytheassemblyofBCsmicellespreparedinsituduringthespin-coatingoftheblockcopolymersolution.BCsinselectivesolventleadtothepreparationofcore-shellmicelleswithadenseinsolublecoreandadiffuseshellpartiallyswollenbythesolventadenseinsolublecore内核

micelles

adiffusecorona核冠第4页/共33页Inthiswork，thepreparationofstablenanostructureassembliesinonestepfromhomogeneoussolutionsofABAtriblockcopolymers.Thesuccessofthisstrategyisessentiallyduetothedesignofverystablemicellespreparedandself-assembledinsituinfewsecondsbysolventevaporationSelf-AssemblyNanomaterials第5页/共33页TheglassyPSANblockswillenabletheformationofcompactaggregatesconstrainingthemicellestobekineticallyfrozenatroomtemperaturewhereastheflexiblePEOblockwillenablethedynamictransitionsbetweenlooped

andbridgedchainconformations.looped

bridged

第6页/共33页PhotonCrossCorrelationSpectroscopyPhotonCrossCorrelationSpectroscopy（PCCS），光子交叉相关光谱法PCCS已用于纳米颗粒粒径测量,其技术日益成熟并成为纳米颗粒粒径测量的有效方法。其测量原理是建立在颗粒的布朗运动之上。随着颗粒的布朗运动,散射光强围绕某一平均值不断起伏涨落。PCCS可以直接测试高浓度试样而不需要稀释。测量结果完全真实的反映了被测试样品的实际粒度及分布状态PCCS测定的参数为：平均粒径和多分散指数吴立敏，王晓艳.纳米、亚微米颗粒粒度的测量——光子相关光谱法,《上海计量测试》，2003年30卷3期第7页/共33页2.ExperimentalPartSythesisoftheTriblockCopolymera.EsterificationPEO+AcryloyolChloride（丙烯酰氯）PEO-acrylate(I)b.IntermolecularRadicalAdditionI+MAMA-SGIalkoxyaminemacroalkoxyamine-basedPEO(II)c.PreparationofTriblockCopolymerII+Styrene+Arylonitrile

P(St317-co-AN262)-b-PEO795-b-P(St-co-AN)PreparationofPolymerFilmsa.DissolvingtheTriblockCopolymerinaDMF/toluenemixtureb.Spin-coatingthehomogeneoussolutionontoaSiwaferevaporatesolvent第8页/共33页SyntheticProducure第9页/共33页3.ResultsandDiscussionSythesisoftheTriblockCopolymerPrecursorPreparationofParticleNanomaterialPreparationof“SpiderWeb”Nanomterial第10页/共33页3.1PreparationofParticleNanomaterialThepreparationofsuperstructurehomogeneoussolution:PSAN-b-PEO-b-PSANselectivesolution：

DMF/toluene(50/50v/v),100mg/mL

spin-coatedonSiwafer

NomicellecouldbedetectedinthesolutionbyPCCS,evenafterincreasingtheconcentrationupto200mg/mL,whichseemstoindicateahighCMCinthissolventsystem.Beyondthisconcentration,thepolymersolutionwastooviscoustobeanalyzed.选择性溶剂DMF，二甲基甲酰胺，极性非质子性溶剂Toluene，甲苯，非极性溶剂第11页/共33页Figure2(A).Self-standingnanoparticlesuperlatticefilmpreparedfromaDMF/toluene(50/50,v/v)copolymersolution.AFMtopviewofthesuperstructureandsizedistributionofparticlediameterdeterminedbyapictureanalysisover100particles.Diameter：c.a.50nmNarrowsizedistributionAFMimage第12页/共33页a

Large-scaledAFMimageofthenanoparticlefilmtopsurface.b,c

3DAFMimagesshowingthehighregularityinroughnesswithZvalue(21.3nm)closetotheRadius(c.a.25nm)ofonepolymerparticle.AdensepackingofnanoparticlesLarge-scaledAFMimage第13页/共33页Figure2(B)SEMtop,bottom,andcrosssectionalviewofastretchednanoparticlefilm.stretchingthefilmcantakeplacewithoutformingcracks.(C)Crackfreestretchednanoparticlefilm.(D)Enlargementofthecross-sectionshowingahomogeneousnanoparticlemorphology.SEMimage第14页/共33页Thewatercontactangle(WCA)ofthenanoparticlefilmwasmeasuredtobe35°,whichconfirmsthepresenceofhydrophilicPEOontheparticlefilmsurface.ThehydrophobicPSANcoreis“shielded”bythePEOcorona，sothesurfacepropertiesofthematerialisonlyrelatedtothethinPEOlayer.推断

不溶性的PSAN嵌段：内核（micellarcore）sphericalmicelle可溶的的PEO嵌段：核冠（micellarcorona）

AdensepackingofnanoparticlesFilmFormationMechanisim

利用水触角测量仪进行电晕处理聚合物薄膜的试验方法第15页/共33页FormationMechanisimofNanoparticleFilmFigure3.theself-assemblyofPSAN-b-PEOb-PSANintonanoparticlefilmABATriblockCopolymer第16页/共33页Aftertheappearanceofmicelles,thesolventevaporationleadstoaprogressivedecreaseofthemicelle-to-micelledistance.Whenmicellesarecloseenoughtointeract,dynamicassociationcouldtakeplacethroughbridgedconformationsoftheABApolymerchains，whichleadstopermanentnanomaterials.第17页/共33页FirstsolubilizedthecopolymerinDMF(100mg/mL)followedbyaslowadditionofwater.DialyzeremoveDMFInthiscase,micellesweredetectedinPCCSinhighconcentrationwithahydrodynamicdiameterof110nm,whichconfirmstheabilityoftheBCtobeassembledintomicellarmorphology.AnalternativestrategyDMF/water第18页/共33页Thisalternativestrategyseemstobelessefficientintermsofparticleorganization.looseDuringthespincoatingofthewater-baseddispersion,micellescomeintocontactwiththesurfaceandstayprobablyataroundthisplacewithoutanyefficientdynamicadjustment.DMF/tolueneDMF/waterLoosenanoparticlefilmDMF/water第19页/共33页ItmustbementionedthatnanoparticlefilmscanalsobeobservedfromBCsolutionsinpureDMF.However,thereproducibilitywaspoor.Smallunwantedchangesintheprocessparametersmightswitchtheorganizationfromnanoparticletoshortworm-likesuperstructurepureDMFRepeatedexperimentMixture:Spherical＆Shortworm-likefilmSphericalmicellefilm第20页/共33页Byaddingsome

toluene,thewindowtotargettheworm-likestructureisenlargedandthereproducibilityisensured.Disconnected

worm-likemicellefilmwithdiameterofabout50nmis

observedbyAFMwhenpuretoluenewasusedassolventAFMtopviewbeforestretchingSEMtopandcross-sectionalviewsafterstretchingFigureS5.Shortdisconnectedworm-likemicellespuretoluenedisconnectedworm-likemicellefilm第21页/共33页Processingisthekeystepandcanalterthequalityofthematerial.ExampleIncreasingthespeedrateofthespincoater,micellesdonothaveenoughtimetoself-organizethroughadynamicprocessandsoroughsurfacewithsomefailurescanbeobserved.FigureS6.AFMimageDMF/toluene(50/50)increasingthespeedrampfrom50to300rpm.s-2.第22页/共33页3.2Preparationof“SpiderWeb”NanomaterialAsdiffusitivityofblockcopolymersinsolutionistoosmalltorespondtothefastchangeofsolventconcentrationandcompositionduringtheevaporationstage,theequilibriummicellemorphologyisneverreached.Inthiswork,byincreasingthetoluenecontentfrom50to75vol%,a“spiderweb”superstructurewithahighlyconnectednetworkofworm-likemicellesisobservedinsteadofananoparticlefilm.第23页/共33页Theworm-likemicelleshaveadiameterof50nmandtheirconnectionsmakeporeswithanaveragesizeof90nmandabroadporesizedistributionFigure5.Self-standing“spiderweb”superlatticefilmobtainedfromaDMF/toluene(25/75,v/v)copolymersolution.Thetopsurfaceoftheinterconnectedworm-likemicellenetworkAFMimage第24页/共33页Theexpected3Dporousnetworkseemsnottobeisotropic,withanorganizationclosetoamultilayersystemwithapreferential2Dconstruction.SEMimageFigure6.SEMcross-sectionalviewofthe“spider-web”nanomaterial.第25页/共33页Duringtheevaporationstage,micelleconcentrationincreasesandsomeinterconnectionstakeplacebetweenmicellesthankstothedynamicformationofbridgedconformationoftheABAtriblockcopolymer.YjunctionLarge-scaledAFMimage第26页/共33页Figure5.(B)theself-assemblyofPSAN-b-PEO-b-PSANintoa“spiderweb”superstructure.FormingMechanism第27页/共33页4.ConclusionsThisstrategyisbasedonthedynamicinteractionsbetweenflower-likemicelles,leadingtoatransitionbetween“loop”and“bridge”conformationsoftheABAchain.Thisbridgeconformationenablestheformationofself-standingcrackfreenanostructuredfilm（无裂缝）Byplayingwiththesolventsystem,sphericalorworm-likemicellesareformedinsituandassemble