嵌段共聚物自組裝納米薄膜

嵌段共聚物自組裝納米薄膜第1頁/共33頁MainReference第2頁/共33頁OutlineIntroductionExperimentalPartResultsandDiscussionConclusionsInnovationsandProblemsReferences第3頁/共33頁1.

IntroductionAmphiphilicblockcopolymers(BCs)couldcontrolmaterialinterfaces.The3DconstructionisdirectedbytheassemblyofBCsmicellespreparedinsituduringthespin-coatingoftheblockcopolymersolution.BCsinselectivesolventleadtothepreparationofcore-shellmicelleswithadenseinsolublecoreandadiffuseshellpartiallyswollenbythesolventadenseinsolublecore內(nèi)核

micelles

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

andbridgedchainconformations.looped

bridged

第6頁/共33頁P(yáng)hotonCrossCorrelationSpectroscopyPhotonCrossCorrelationSpectroscopy（PCCS），光子交叉相關(guān)光譜法PCCS已用于納米顆粒粒徑測(cè)量,其技術(shù)日益成熟并成為納米顆粒粒徑測(cè)量的有效方法。其測(cè)量原理是建立在顆粒的布朗運(yùn)動(dòng)之上。隨著顆粒的布朗運(yùn)動(dòng),散射光強(qiáng)圍繞某一平均值不斷起伏漲落。PCCS可以直接測(cè)試高濃度試樣而不需要稀釋。測(cè)量結(jié)果完全真實(shí)的反映了被測(cè)試樣品的實(shí)際粒度及分布狀態(tài)PCCS測(cè)定的參數(shù)為：平均粒徑和多分散指數(shù)吳立敏，王曉艷.納米、亞微米顆粒粒度的測(cè)量——光子相關(guān)光譜法,《上海計(jì)量測(cè)試》，2003年30卷3期第7頁/共33頁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頁/共33頁SyntheticProducure第9頁/共33頁3.ResultsandDiscussionSythesisoftheTriblockCopolymerPrecursorPreparationofParticleNanomaterialPreparationof“SpiderWeb”Nanomterial第10頁/共33頁3.1PreparationofParticleNanomaterialThepreparationofsuperstructurehomogeneoussolution:PSAN-b-PEO-b-PSANselectivesolution：

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

spin-coatedonSiwafer

NomicellecouldbedetectedinthesolutionbyPCCS,evenafterincreasingtheconcentrationupto200mg/mL,whichseemstoindicateahighCMCinthissolventsystem.Beyondthisconcentration,thepolymersolutionwastooviscoustobeanalyzed.選擇性溶劑DMF，二甲基甲酰胺，極性非質(zhì)子性溶劑Toluene，甲苯，非極性溶劑第11頁/共33頁Figure2(A).Self-standingnanoparticlesuperlatticefilmpreparedfromaDMF/toluene(50/50,v/v)copolymersolution.AFMtopviewofthesuperstructureandsizedistributionofparticlediameterdeterminedbyapictureanalysisover100particles.Diameter：c.a.50nmNarrowsizedistributionAFMimage第12頁/共33頁a

Large-scaledAFMimageofthenanoparticlefilmtopsurface.b,c

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

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

AdensepackingofnanoparticlesFilmFormationMechanisim

利用水觸角測(cè)量?jī)x進(jìn)行電暈處理聚合物薄膜的試驗(yàn)方法第15頁/共33頁FormationMechanisimofNanoparticleFilmFigure3.theself-assemblyofPSAN-b-PEOb-PSANintonanoparticlefilmABATriblockCopolymer第16頁/共33頁Aftertheappearanceofmicelles,thesolventevaporationleadstoaprogressivedecreaseofthemicelle-to-micelledistance.Whenmicellesarecloseenoughtointeract,dynamicassociationcouldtakeplacethroughbridgedconformationsoftheABApolymerchains，whichleadstopermanentnanomaterials.第17頁/共33頁FirstsolubilizedthecopolymerinDMF(100mg/mL)followedbyaslowadditionofwater.DialyzeremoveDMFInthiscase,micellesweredetectedinPCCSinhighconcentrationwithahydrodynamicdiameterof110nm,whichconfirmstheabilityoftheBCtobeassembledintomicellarmorphology.AnalternativestrategyDMF/water第18頁/共33頁Thisalternativestrategyseemstobelessefficientintermsofparticleorganization.looseDuringthespincoatingofthewater-baseddispersion,micellescomeintocontactwiththesurfaceandstayprobablyataroundthisplacewithoutanyefficientdynamicadjustment.DMF/tolueneDMF/waterLoosenanoparticlefilmDMF/water第19頁/共33頁ItmustbementionedthatnanoparticlefilmscanalsobeobservedfromBCsolutionsinpureDMF.However,thereproducibilitywaspoor.Smallunwantedchangesintheprocessparametersmightswitchtheorganizationfromnanoparticletoshortworm-likesuperstructurepureDMFRepeatedexperimentMixture:Spherical＆Shortworm-likefilmSphericalmicellefilm第20頁/共33頁Byaddingsome

toluene,thewindowtotargettheworm-likestructureisenlargedandthereproducibilityisensured.Disconnected

worm-likemicellefilmwithdiameterofabout50nmis

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