Selective Coating of Single Wall Carbon Nanotubes with Thin SiO2 Layer

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1、NANOLETTERSSelectiveCoatingofSingleWallCarbon2002Vol.2,No.4NanotubeswithThinSiO2Layer329-332QiangFu,ChenguangLu,andJieLiu*GrossChemistryLaboratory,DukeUniVersity,Box90354,Durham,NorthCarolina27708ReceivedJanuary27,2002;RevisedManuscriptReceivedFebruary19,2002ABSTR

2、ACTSinglewalledcarbonnanotubes(SWNTs)havebeenshowntobehighlysensitivegassensors.However,attachingfunctionalgroupswithselectivesensingfunctionsonnanotubeswithoutdestroyingtheintrinsicelectronicpropertyofthenanotubesisstillchallenging.Here,wereportanewmethodofcoatin

3、gSWNTswithathinlayerofSiO2using3-aminopropyltriethoxyysilaneascouplinglayers.ThethicknessoftheSiO2couldbecontrolledatabout1nm.ThecoatingofSiO2onSWNTswasconfirmedbyburningtheSWNTsinair.Theeffectof3-aminopropyltriethoxyysilanewasalsodiscussed.Carbonnanotubeshavebeen

4、themostactivelystudiedpingandcoatingbypolymersandsurfactantswerere-materialsinthepastfewyearsduetotheiruniqueelectronicported.13-15Morerecently,coatingwiththicklayerofSiO2andmechanicalproperties.1,2CarbonnanotubescanbeeitheronMWNTsforcompositeapplicationshavebeenr

5、eported.12metallicorsemiconductive,dependingontheirhelicityandHowever,sofar,thereisnoflexiblemethodthatcoulddiameter.Moreimportantly,itwasobservedthatthefunctionalizeSWNTswithabroadvarietyoffunctionalities.electronicpropertiesofnanotubes,especiallysemiconductingHe

6、re,wereportanewmethodtoselectivelyfunctionalizecarbonnanotubes,areverysensitivetothesurroundingSWNTssidewallswithathinlayerofSiO2,whichcouldenvironments.Thepresenceofoxygen,NH3andmanyotherofferflexiblewaysforfurthermodificationbyutilizingthemoleculesthatcaneitherd

7、onateorremoveelectronsfromrichchemistryavailableforsilicasurface.Ourapproachthenanotubescansignificantlyaltertheoverallconductivityinvolvestheuseofapromoter,3-aminopropyltriethanox-ofthenanotubes.3-5Suchpropertiesmakecarbonnanotubesysilane(APTES),whichcouldbeabsor

8、bedonthesidewallsidealcandidatesfornanoscalesensingmaterials.Actually,ofSWNTbytheinteractionbetweenaminegroupsanditwasreportedthatnanotubesFETscanfuncti