电子纸2207803678

SCIENCECHINAChemistry©ScienceChinaPressandSpringer-VerlagBerlinHeidelberg2011chem.scichina.comwww.springerlink.com*Correspondingauthor(email:[e-mail])•ARTICLES•February2011Vol.54No.2:385–391·SPECIALISSUE·InHonorofthe80thBirthdaysofProfessorsSHENJiaCong,SHENZhiQuanandZHUORenXidoi:10.1007/s11426-010-4203-9Microcapsuleswithcompactwallfromhydrocarbon/fluorocarboncompositesurfactantsforelectrophoreticdisplayDAIRunYing,WUGang*&CHENHongZhengMOEKeyLaboratoryofMacromoleculeSynthesisandFunctionalization;DepartmentofPolymerScienceandEngineering,StateKeyLaboratoryofSiliconMaterials;ZhejiangUniversity,Hangzhou310027,ChinaReceivedSeptember29,2010;acceptedOctober26,2010Thecomponentsandtheirconcentrationratioofsurfactantmixtureinaqueoussolutionofgelatinandsodiumcarboxymethyl-cellulose(NaCMC)areveryimportantduringthepreparationofstablemicrocapsulesforelectrophoreticdisplay.Inthiswork,hydrocarbon/fluorocarboncompositesurfactantwasintroducedforthefirsttimeintothecapsulewalltoimprovethechemicalresistanceandbarrierpropertyofthemicrocapsules.ByinvestigatingsurfacetensionandzetapotentialofNaCMCwiththemixtureofsodiumdodecylsulfate(SDS)/perfluoro-noneneoxybenzenesulfonate(OBS),wefoundthatboththepresenceofhydrophobicinteractionandthehydrogenbondingbetweenNaCMCandSDS/OBSenhancedtheadsorptionofNaCMCattheoil/waterinterfaceandthusfacilitatedtheformationofcapsulewall.Themorphology,particlesize,surfacefreeenergyandthermalstabilityoftheobtainedmicrocapsuleswerecharacterized.Theresultsshowedthatopticallytransparentmicrocapsuleswithuniformsize,smoothsurfaceandcompactwallcanbeobtainedbyadjustingthepHvalueofthereactionsystemandtheconcentrationratioofSDS/OBS.Basedonthepreparedmicrocapsules,amatrixdisplayprototypeoperatedat9Vdirectcur-rentinstaticdrivenmodewasfabricated.microcapsules,compactwall,sodiumcarboxymethylcellulose,sodiumdodecylsulfate/perfluoro-noneneoxybenzenesulfonatecompositesurfactant,electrophoreticdisplay1IntroductionComparedwithothersurfactants,fluorocarbonsurfactantsexhibithighersurfaceactivity,betterthermalstabilityandchemicalstabilityagainstacidic,basic,andoxidativecondi-tions[1].Thesetypicalpropertiescanbeattributedtothereplacementofhydrogenatomsbyfluorineatomsinthehydrophobicgroupsofperfluorocarbonsurfactantmole-cules.Byvirtueofthelargervolumeandhigherelectro-negativityofFatomthanHatom,thehydrophobicityandsurfaceactivityofthefluorocarbonsurfactantwereim-proved,andthecriticalmicelleconcentration(CMC)andsurfacetensionweredecreased[2,3].Compositesurfac-tantshaveattractedgreatinteresttotailortheirchemicalandphysicalpropertiesbychangingtheinvolvedcomponentsandtheirconcentrationratioofsurfactantcomposites.MukerjeeandYang[4]firstlyproposedthatcoexistingmi-celles,onerichinfluorocarbonandtheotherinhydrocar-bon,couldbepreparedbymixingsodiumperfluorooc-tanoateandhydrocarbonsurfactants.Dongetal.[2]inves-tigatedthemixtureofdiethanolheptadecafluoro-2-undeca-nolmethyl-ammoniumchloride(DEFUMACl)anddodecyl-trimethyammoniumchloride(DTACl)by19FNMRandfoundthatthereexistedbothDEFUMACl/DTAClmixedmicellesandindividualDEFUMAClmicellesinthesamesystem.Inthecaseofhydrocarbonandfluorocarboncompositesur-factants,theformercomponentcanreducetheoil-waterinterfacialtension,andthelatteraidstodecreaseair-watersurfacetension[5].Thus,suchacompositesurfactantshowsalowersurfacetension,alowerCMC,ahighersurfaceac-tivitythanthoseofindividualsurfactants[6].386DaiRY,etal.SciChinaChemFebruary(2011)Vol.54No.2Thestabilityofmicrocapsulesappliedinelectrophoreticdisplay(EPD)dependsheavilyonthebarrierpropertyofcapsulewall.Itisknownthatfluorinationcanenhancethechemicalresistanceandthebarrierpropertiesofpolymers.Usingsurface-fluorination,Joffre[7]improvedthebarrierpropertyofhigh-densitypolyethyleneagainstnon-polarsolventpermeation.Modificationofpolyisoprenewithfluorochlorocarbeneenhanceditsthermalstability[8].Blendingperfluorocarbonsurfactantwithhydrocarbonsur-factantasonecomponentofcapsulewallmaterialsisafacilemethodtointroducefluorineintothecapsulewall.Bythismeans,thestabilityofthemicrocapsulescanbeim-proved.However,mostperfluorocarbonsurfactantsexhibitpoorsolubilityatroomtemperature,confiningtheirconcen-trationsinthesurfactantmixtures.Perfluoro-noneneoxybenzenesulfonate(OBS),owningahighsolubilityduetoitsC=Cdoublebondsandoxygenfunctionalgroups,turnsouttobethemostappropriateperfluorocarbonsurfactantforourpurpose.Inthisstudy,byexploitingsodiumdodecylsulfate(SDS)/OBSmixedsurfactantintheaqueoussolutionofgelatinandsodiumcarboxymethylcellulose(NaCMC),wepreparedmicrocapsulesforEPDapplication.Thestabilityofmicro-capsuleswasenhancedowingtothehighsurfaceactivity,thermalstability,andchemicalresistanceofOBSandtheinteractionsbetweenNaCMCandmixedSDS/OBScom-positesurfactants.ByoptimizingthepHvalueofthesystemandtheconcentrationratioofSDS/OBS,theopticallytransparentmicrocapsuleswithcompactwallandhighbar-rierpropertyweresuccessfullyobtained.2Experimental2.1MaterialsGelatin(typeB,alkaliprocessed,isoelectricpointpH4.7),sodiumcarboxymethylcellulose,glutaraldehyde(25%),so-diumdodecylsulf