Silver nanocrystals by hyperbranched polyurethane-assisted p

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MaterialsChemistryandPhysics81(2003)

104–107

Silvernanocrystalsbyhyperbranchedpolyurethane-assisted

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photochemicalreductionofAg光化学

H.W.Lu,S.H.Liu,X.L.Wang,X.F.Qian ,J.Yin,Z.K.Zhu

ResearchInstituteofPolymerMaterials,SchoolofChemistryandChemicalTechnology,

ShanghaiJiaoTongUniversity,Shanghai200240,PRChinaReceived11April2002;receivedinrevisedform4March2003;accepted4March2003

超支化聚氨酯

Abstract

Silvernanoparticlesinhyperbranchedpolyurethane(HP)matrixwerepreparedbymeansofUVirradiationatroomtemperature.HPwasfoundtoplayakeyroleinthephotochemicalreductionofsilverionsandtheformationofnanosizedparticles.Transmissionelectronmicroscopic(TEM)analysisshowedthatsilvernanoparticleswerehomogeneouslydispersedinHPmatrix.Theabsorptionpeaksduetothesurfaceplasmonresonanceoftheobtainedsilvernanoparticleswereobservedatabout430nmintheultraviolet-visible(UV-Vis)

表面等离子共振

absorptionspectra.X-raypowderdiffraction(XRD)wasalsousedtocharacterizetheobtainednanoparticles.©2003ElsevierScienceB.V.Allrightsreserved.

Keywords:Nanostructures;Polymers;Opticalproperties

照射

1.Introduction

金属纳米颗粒的合成方法

Inthepastdecade,nanoparticlesofnoblemetalshavebeeninvestigatedintensivelyduetotheirpotentialapplica-tionsinmicroelectronics[1–3],andtheiroptical,electric,andcatalyticproperties[4–6].Manywetchemicalmethods,whichincludesolid–liquid-phasearcdischarge[7],ultravi-oletirradiationphotoreduction[8],andapulsesonoelectro-chemicalmethod[9]havebeenreportedforthesynthesisofmetalnanoparticles.

Recently,theapplicationofdendrimers,whichhaveuniquestructuresandproperties,hasopenedanewwayofproducingmetalnanoparticleswithsmallsizeandnarrowsizedistribution[7,10].Dendrimersusuallytakeasphericalthree-dimensionalstructure,whichisverydifferentfromlinearpolymersadoptingarandom-coilstructure,soden-drimersmightprovidereactionsitesincludingtheirinteriororperiphery[11].Tillnow,manynanoparticlessynthesizedindendrimershavebeenreported[11–13].Forexample,Esumietal.preparednanoparticlesofgold,platinum,andsilverbyreductionoftheirmetalsaltswithNaBH4inthepresenceofpoly(amidoamine)dendrimers[11].However,thesyntheticschemeofdendrimerswhichhaveawellde nedandperfectlybranchingstructureisusuallycom-Correspondingauthor.Tel.:+86-21-54743268;fax:+86-21-54741297.

E-mailaddress:xfqian@(X.F.Qian).

贵金属－－－银

plicated.Asanalternative,hyperbranchedpolymerscanbepreparedbyamucheasierprocess.Althoughhavingalessperfectstructurethandendrimers,hyperbranchedpolymersstillmaintainmanyofthearchitecturalfeaturesfoundintheirmoreperfectlyde neddendriticcounterpartsandare

树枝

supposedtoexhibitpropertiesresemblingthoseofden-driticones[14,15].Itissurprising,however,thatreportsonthepreparationofmetalnanoparticlesinhyperbranchedpolymersarestilllimited.

Herein,wepresentedahyperbranchedpolyurethane(HP)-assistedphotochemicalmethodforproducingsilvernanoparticlesbymeansofUVirradiation.ItwasfoundthatthesilvernanoparticleswerehomogeneouslydispersedintheHPmatrixandexhibitedanUV-Visabsorptionpeak,correspondingtothecharacteristicsurfaceplasmonreso-nanceofsilverparticles.2.Experimental

Allthereactantsandsolventswereofanalyticalgrade.HPwassynthesizedaccordingto[16].A250Whigh-pressuremercurylampwasusedastheultravioletirradiationsource.水银灯

Inatypicalpreparationprocess,0.1gAgNO3wasdissolvedinthesolutionof0.5gHPdissolvedin20mlethanolun-dervigorousstirring.Thesolutionswerethenirradiatedfor4,24,and36h,respectivelyunderultravioletirradiationatroomtemperature.Theobtainedblackviscoussolutionwas

紫外照射不同时间：４，２４，３６小时

0254-0584/03/$–seefrontmatter©2003ElsevierScienceB.V.Allrightsreserved.doi:10.1016/S0254-0584(03)00147-0