Synthesis of Fe 3O 4@Polyaniline Core/Shell Microspheres with Well-Defined Blackberry-Like Morphology
Shouhu Xuan,†,‡Yi-Xiang J.Wang,§Ken Cham-Fai Leung,*,‡and Kangying Shu*,†
我的奇思妙想300字作文Department of Materials Science and Engineering,China Jiliang Uni V ersity,Hangzhou,310018,People’s Republic of China;,The Center of No V el Functional Molecules and Department of Chemistry,The Chine Uni V ersity of Hong Kong,Shatin,NT,Hong Kong SAR;,Department of Radiology,Prince of Wales Hospital,The Chine Uni V ersity of Hong Kong,Shatin,NT,Hong Kong SAR Recei V ed:August 9,2008;Re V id Manuscript Recei V ed:October 3,2008
Superparamagnetic Fe 3O 4@polyaniline core/shell microspheres with well-defined blackberry-like morphology have been synthesized via a simple in situ surface polymerization method.The thickness of the polyaniline (PANI)shell can be lectively obtained by tuning the reaction time and monomer concentration.The poly(vinylpyrroldine)(PVP)plays an important role in the coating process.The prent method can be extendable to fabricate other magnetic/conductive core/shell composites,and the unique core/shell spherical materials could find applications in catalyst supports or biomedical areas.
1.Introduction
Core/shell structured particles,1especially magnetic nano-composite materials,2have attracted increasing attention becau they offer the possibility of a new generation of nanostructured materials with diver applications for their unique magnetic responsivity,low cytotoxicity,and chemically liable surface.Among the magnetic core/shell particles,superparamagnetic materials do not retain any magnetization in the abnce of an externally applied magnetic field.Due to this property,3super-paramagnetic core/shell particles are of great interest for applications in magnetic resonance imaging,hyperthermia,paration and purification of biomolecules,drug delivery,and catalysis.4
扇子妈In such applications,functional materials are often ud as a protective coating shell to ensure the stability of the inner magnetic core and as the intrinsic functions of the core/shell particles being electron-conductive,biocompatible,inert,hy-drophilic,or hydrophobic,etc.5Polyaniline (PANI)is one of the most technologically important materials becau of its environmental stability in a conducting form,unique redox properties,and high conductivity with suitable dopants.6PANI composite materials posss the potential for a multitude of applications,such as in gas nsors and inductors.7Therefore,conductive organic/inorganic nanocomposites have recently been studied inten
sively.8Concerning the above-stated fields of rearch,superparamagnetic and conducting polymer hybrid materials in which inorganic magnetic cores are augmented with insoluble outer layers of conductive PANI belong to an important class of materials.9
Recently,bifunctional PANI/Fe 3O 4nanocomposites have attracted intensive attention for applications of nanomaterials due to their novel magnetic and conductive properties.Wan et al.10studied a ries of PANI composites containing nanomag-nets prepared by chemical polymerization.Deng et al.11reported
the preparation of PANI/Fe 3O 4nanoparticles with core/shell structure via an in situ polymerization of aniline monomer in an aqueous solution,which contained Fe 3O 4nanoparticles and surfactants.Peng’s group 12described the fabrication of nanoscale ferromagnetic Fe 3O 4-cross-linked PANI by an oxidative po-lymerization of aniline with ammonium peroxodisulfate as the oxidant.The resulting core/shell particles are polydisperd,having an average diameter of 20-30nm.In the studies,Fe 3O 4with a size of less than 10nm that exhibit low magnetization 13were ud becau their superparamagnetic properties eliminated magnetic force-induced lf-aggregation of the particles.However,such methods result in fluctuations in the size for which the as-synthesized particles had a nonuniform magnetite fraction in each nanosphere due to nanoscale clu
stering of magnetic particles.Furthermore,many of the materials show relatively a small amount of magnetic contents,which usually resulted in the reduction of their respon to magnetic fields.It is therefore of interest to achieve high loads of superparamagnetic materials in each PANI/Fe 3O 4particle,keeping in mind that each particle should have a well-defined,core/shell-like structure.
To date,effective coating of magnetic particles with natural or synthetic polymers is still a challenge,since the surfaces of magnetic particles are hydrophilic but polymers are hydrophobic.Therefore,development of a versatile method to directly coat PANI onto Fe 3O 4particles is still challenging.Herein,we report a novel synthesis of Fe 3O 4@PANI core shell microspheres via a simple in situ surface polymerization method.Through this surface-modified procedure,high-content superparamagnetic Fe 3O 4containing Fe 3O 4@PANI microparticles were obtained with well-defined blackberry-like morphology.Although we have demonstrated this procedure only with a Fe 3O 4core and PANI shell as examples,it is believed that this method should be extendible to other magnetic core materials (Fe,γ-Fe 2O 3,Co,Ni,and ferrite)and to a range of other conductive shell materials (such as polypyrrole,polythiophene,etc).2.Experimental Section
Materials.Ferric chloride hexahydrate (FeCl 3·6H 2O),sodium acetate (CH 3COONa),ethylene glycol (C 2H 6O 2),3-aminopro-
环比增长什么意思
*Corresponding author.Tel:+8657186835740.Fax:+865718683-5740.E-mail:(K.S.),(K.C.-F.L.)cfleung@cuhk.edu.hk.†China Jiliang University.
‡The Center of Novel Functional Molecules and Department of Chemistry,The Chine University of Hong Kong.
§Prince of Wales Hospital,The Chine University of Hong Kong.
J.Phys.Chem.C 2008,112,18804–18809
1880410.1021/jp807124z CCC:$40.75 2008American Chemical Society
Published on Web 11/08/2008
东北冬天pyltriethoxysilane(APTES),absolute ethanol(95wt%),am-monium peroxodisulfate((NH4)2S2O8;APS),and poly(vinylpyr-rolidone)(PVP;30kDa,95wt%)were purchad from Sinopharm Chemical Reagent Co.,Ltd.All chemicals were of analytical grade and ud without further purification.Aniline was obtained from Beijing Xingjin Chemical Factory and was distilled at a reduced pressure before u.Doubly deionized water was ud through all the process.
Synthesis and Chemical Modification of Fe3O4Particles. The magnetic Fe3O4particles were prepared through a solvo-thermal reaction.Briefly,FeCl3·6H2O(1.35g)and sodium acetate(3.6g)were dissolved in ethylene glycol(40mL)under magnetic stirring.The obtained homogeneous yellow solution was transferred to a Teflon-lined stainless-steel autoclave and aled to heat at200°C.After reaction for8h,the autoclave was cooled to room temperature.The obtained black magnetite particles were washed with ethanol six times and then dried in vacuum at60°C for12h.Subquently,the Fe3O4particles were chemically modified by using APTES.Typically,Fe3O4 microspheres(0.1g)and APTES(2mL)were dissolved in anhydrous ethanol to give a mixture solution(50mL).The mixture was refluxed for12h under dry nitrogen.The resulting modified Fe3O4particles were parated with the help of a
magnet and then washed with ethanol.Finally,the product was dried in vacuum at60°C for24h to obtain the amine-functionalized Fe3O4particles(NH2-Fe3O4).
Synthesis of Fe3O4@PANI Microparticles.The bifunctional Fe3O4@PANI microspheres with blackberry-like morphology were prepared by an in situ surface polymerization method in the prence of PVP.In a typical procedure,PVP(0.05g)was dissolved in130mL of deionized water,and then the NH2-Fe3O4particles(0.015g)were added.The mixture was then ultrasonically disperd,and
a solution of aniline(20µL) in HCl(0.1mL)was added into the mixture with vigorous stirring.Afterward,the mixture was mechanically stirred for 30min at20°C.Then an aqueous solution(20mL)of APS (0.2g)was added into the above mixture instantly to start the oxidative polymerization.The reaction was performed under mechanical stirring for5h.The resulting precipitates were washed with deionized water and ethanol veral times.Finally, the product was dried in vacuum at60°C for24h to obtain of the desired Fe3O4@PANI composite as a dark powder. Characterization.X-ray powder diffraction patterns(XRD) of the products were obtained on a Japan Rigaku DMax-γA rotation anode X-ray diffractometer equipped with graphite monochromatized Cu K R radiation(λ)1.54178Å).Transmis-sion electron microscopy(TEM)photographs were taken on a Hitachi model H-800transmission electron microscope at an accelerating voltage of200kV.Thefield emission scanning electron microscopy(FE-SEM)images were taken on a JEOL JSM-6700F SEM.X-ray photoelectron spectra(XPS)were measured on a photoelectron spectrometer using Mg K R radiation.Infrared(IR)spectra were recorded in the wavenum-bers ranging from4000to500cm-1with a Nicolet model759 Fourier transform infrared(FT-IR)spectrometer using a KBr wafer.Thermogravimetric analys were conducted with a Netzsch STA409C thermoanalyzer instrument.Their magnetic properties(M-H curve)were measured at room temperature on a MPMS XL magnetometer made by Quantum Design Corporation.
3.Results and Discussion
Precily size-regulated magnetic particles are esntial to control the Fe3O4content in each core/shell sphere.Here,we employed a previously described solvothermal method to prepare well-disperd Fe3O4microspheres.14Since each of them is compod of many small primary nanocrystals,the Fe3O4 spheres retain superparamagnetic behavior at room temperature while posssing higher saturation magnetization.Additionally, the magnetic cores can be synthesized with tunable sizes ranging from200to1500nm.Therefore,the Fe3O4micro-spheres are the most suitable template to fabricate superpara-magnetic core/shell particles.Many strategies have also been developed to construct various inorganic-inorganic core/shell or sandwichlike structures by coating the cores with SiO2,15 porous SiO2,16and TiO2.17In this work,in contrast,we prepared exquisite inorganic-organic bifunctional Fe3O4@PANI core/ shell structures with the approximate size of Fe3O4microspheres, about350nm.
The Fe3O4microspheres were coated with uniform shells of PANI via an in situ surface polymerization method at room temperature.Figure1shows the reprentative TEM images of Fe3O4@PANI composites.A continuous layer,which exhibits afine increment in brightness in comparison to the dark inner core,is clearly obrved on the outer shell of the Fe3O4 microsphere c
ores,as shown in Figure1a.Figure1b shows the TEM image of a single Fe3O4@PANI particle with a typical core/shell structure.In comparison with Fe3O4@PANI(Figure 1b)and the pristine Fe3O4microsphere(Figure7a),there are two majorfindings that can be easily obrved:(1)there is no obvious change in the average particle size for the Fe3O4 particles before and after being coated with PANI,and(2)the resultant Fe3O4@PANI composites also posss a well-disperd nature and spherical shape.It reveals that the Fe3O4particles act as a template for the deposition of PANI during the reaction. Clearly,the Fe3O4@PANI composites contain well-defined core/shell-like structure,and the thickness of the PANI shell is about35nm.Moreover,the TEM images with higher resolutions (Figure1c,d)reveal that the PANI coating is relatively rough, compod of nanoparticles with sizes of30-60nm,which are deposited on the surface of the Fe3O4core.
To further characterize the size and shape of the prented Fe3O4@PANI composites,FE-SEM inspection was conducted. Figure2a and b depict typical SEM images of Fe3O4@PANI microspheres,indicating that the core/shell products are
梦见吃核桃well-Figure1.(a-d)TEM images of the as-prepared Fe3O4@PANI core/ shell composite with increasing magnification.Note the scale bar.
Synthesis of Fe3O4@PANI Core/Shell Microspheres J.Phys.Chem.C,Vol.112,No.48,200818805
disperd with near-spherical morphology,which is similar to the results obtained from TEM.From the SEM images with higher resolutions (Figure 2c and d),it can be clearly obrved that many tiny nanoparticles are located on the microparticles’surfaces.The size of the tiny nanoparticles ranges from 30to 60nm,which agrees with the TEM results.As a conquence,the TEM and SEM obrvations strongly demonstrate that our obtained Fe 3O 4@PANI composites posss well-defined core/shell structures with uniform blackberry-like shape.
Figure 3shows the XRD patterns of the Fe 3O 4microsphere and Fe 3O 4@PANI composites.All detected diffraction peaks in Figure 3a could be indexed as face centered cubic (fcc)Fe 3O 4(JCPDS card No.19-629).No other characteristic peaks due to the impurities of hematite or hydroxides were detected.The broadened nature indicates that the Fe 3O 4microspheres obtained by the prent solvothermal route consist of nanoparticles with a diameter of 15nm,which is well in accordance with previous reports.16For the XRD spectrum of the Fe 3O 4@PANI composite (Figure 3b),the main pea
ks are similar to the pristine Fe 3O 4particles (Figure 3a),which reveals that the crystal structure of Fe 3O 4is well-maintained after the coating process under acidic conditions.Becau of the relatively thin layer and amorphous crystallinity of the PANI prepared under this polymerization method,no obvious diffraction peak for the PANI is obrved.Moreover,the successful polymerization of aniline onto the Fe 3O 4core was confirmed by Fourier transform infrared spectroscopy (FTIR),as shown in Figure 4b.It reveals that
Fe 3O 4@PANI composite microspheres have characteristic peaks at around 1593(C d C stretching deformation of quinoid and benzenoid ring,respectively),1315(C -N stretching of cond-ary aromatic amine),1165,and 837cm -1(out of plane deformation of C -H in the 1,4-disubstituted benzene ring),18which are similar to that of the PANI sample without Fe 3O 4microcores under the same conditions (Figure 4c).The relatively high intensity of a band at 594cm -1(Fe -O stretching of Fe 3O 4)19indicates the low content of PANI in the Fe 3O 4@PANI composite,which was further confirmed by the following TG analysis.Figure 5illustrates the results of the thermogravimetric analysis of the Fe 3O 4@PANI composite,for which the thermal degradation of the PANI occurs at 450°C.The initial
mass
Figure 2.(a -d)SEM image of the as-prepared Fe 3O 4@PANI core/shell composite with increasing
magnification.
Figure 3.XRD patterns of (a)Fe 3O 4and (b)Fe 3O 4@PANI core/shell
composite.
Figure 4.FTIR spectroscopy of (a)Fe 3O 4,(b)Fe 3O 4@PANI,and (c)
PANI.
Figure 5.TG curve of the as-prepared Fe 3O 4@PANI core/shell
composite.
Figure 6.XPS spectrum of the as-prepared Fe 3O 4@PANI core/shell composite.
18806J.Phys.Chem.C,Vol.112,No.48,2008Xuan et al.
loss at lower temperatures is mainly due to the relea of water and dopant anions from the PANI.A sharp loss in mass is obrved at 300°C and continues to 650°C,possibly due to a large scale thermal degradation of the PANI chains.From the TG analysis,the mass ratio of the Fe 3O 4in the magnetic core/shell composite is about 66%.
XPS has often been ud for the surface characterization of various materials,and unambiguous results are readily obtained when each of the various surface components contains unique elemental markers.Here,to further analyze the PANI shell in the core/shell product,XPS (Figure 6)was employed to understand the composition of the particle surface.It is obvious that the main content of the surface is C,O,and N elements.The binding energy at 710.20eV for Fe2p3cannot be detected,which further supports that all Fe 3O 4cores in the composite are confined within a shell of PANI,in agreement with the TEM and SEM analys.
The thickness of the PANI shells strongly depends on a number of parameters,including the reaction/incubation time,the initial concentrations of aniline,and the reaction temperature.We found that it was most convenient and reproducible to control the thickness of PANI coatings by adjusting the concentration of the aniline precursor.Figures 7a -d show the TEM images of Fe 3O 4@PANI composites synthesized from different aniline concentrations.All the products were obtained starting from Fe 3O 4beads of 350nm by allowing the growth of PANI to proceed for the same period of time (5h).By simply altering the concentration of aniline from 1.1to 2.2mM,the thickness of the deposited PANI could be varied in the range from 10to 50nm.The concentration of aniline had to be controlled in the range of 1.1-2.2mM for the polymerization in the prent work.When the concentration of aniline was reduced to 0.55mM,the PANI derived from the precursor appeared to be insufficient to form a complete shell on the surface of each Fe 3O 4sphere (Figure 7a).As the concentration of aniline was incread to 1.1mM,the surface of each Fe 3O 4sphere was coated with a complete shell of PANI with a thickness of ∼10nm (Figure 7b).The PANI shells’thickness continued to increa to 35nm when the concentration of aniline was incread to 1.65mM (Figure 7c).As the concentration was incread beyond 2.2mM,the surface of each Fe 3O 4sphere was coated with a uniform shell of PANI with about 50nm (Figure 7d).However,a significant number of PANI gel spheres attached on the magnetic spheres were also obrved in the final
product as a result of unsuppresd homogeneous nucleation.The obrvations imply that the concentration of the aniline precursor has to be optimized to obtain reproducible,uniform core/shell particles by avoiding incomplete coating of the Fe 3O 4spheres.
Furthermore,the thickness of the PANI could be tuned by controlling the reaction time.Here,when the reaction time was 3h,with a constant polymerization temperature,amount of Fe 3O 4spheres,and aniline precursor concentration,the thickness of PANI shells was ∼7nm (Figure 7e).If the reaction time was prolonged to 5h,the thickness of the PANI shell could increa up to 35nm (Figure 7f).As shown in Figure 7g,the PANI shell thickness incread to 45nm when the reaction time was prolonged to 7h.However,under this condition,some individual bulk PANI particles existed in the Fe 3O 4@PANI composites such that the PANI particles were barely linked to each other.Obviously,the longer reaction time can produce more PANI materials in the product which finally induced PANI floccules.Therefore,in our experiment,the optimum reaction time for the fabrication of well-defined core/shell structure is 5h.
The synthetic procedure for the Fe 3O 4@PANI core/shell composite is schematically illustrated in Figure 8.In our system,Fe 3O 4spheres were prepared according to the method given in previous reports.14To overcome the intrinsic hydrophilic character of the Fe 3O 4particles and to favor the gro
wth of PANI nodules on their surface,a coupling agent is needed.Therefore,the periphery of prepared Fe 3O 4particles was modified with amine groups to improve their affinity to PANI.The amine-modified Fe 3O 4particles were redisperd in aqueous
solution.
Figure 7.TEM images of the Fe 3O 4@PANI composite prepared under different conditions.(a -d)Varying monomer concentrations:(a)0.55,(b)1.1,(c)1.65,and (d)2.2mM.(e -g)Varying reaction times:(e)3,(f)5,and (g)7h.(h)No PVP
added.
xXx19
Figure 8.Schematic illustration of the synthesis process of Fe 3O 4@PANI core/shell composite.
Synthesis of Fe 3O 4@PANI Core/Shell Microspheres J.Phys.Chem.C,Vol.112,No.48,200818807
Before the polymerization reaction,PVP was added to the solution.Being an amphiphilic and nonionic surfactant,PVP usually formed a polymer coil in aqueous solution under a dilute concentration.20Due to the prence of pyrrolidone groups,the PVP macromolecules could be attached on the peripheral amine functions of the Fe 3O 4particles by hydrogen bonds.The PVP macromolecules that attached onto the surface of the Fe 3O 4are very important for the formation of the resulting core/shell structure.Figure 7h shows a typical image of the product prepared from the unmodified Fe 3O 4.It is obvious that PANI nanoparticles could not be coated effectively on the Fe 3O 4surface.Moreover,without the prence of PVP,well-defined core/shell particles could not be obtained.Afterward,the aniline monomers were added and converted to cationic anilinium ions under acidic conditions.Once PANI nucleation was generated,the grains might be stabilized by the PVP molecules that attached onto the Fe 3O 4surface.21The polymerization usually took place preferentially and continuously in proximity to existing PANI.Hence,the polymerization was successfully initiated,propagated,and terminated on the surface of the Fe 3O 4core rather than in solution.Eventually,a homogeneous,continuous,and uniform PANI shell was formed on the surface of
the Fe 3O 4core.Accounting for the stabilization of PANI grains by the PVP macromolecules,the peripheral coating consisted of many PANI nanoparticles.Hence,Fe 3O 4@PANI core/shell particles with a blackberry-like morphology were subquently obtained by this in situ polymerization method.On the basis of all the previous results,the mechanism for the shell formation on the amine-modified Fe 3O 4particles can be propod.The amine modification endows the affinity between the PVP and the template surface.PVP plays two roles here:First is to rve as a linker between the PANI nanoparticles and the Fe 3O 4surface.Second is to rve as a stabilizer to stabilize the amine-modified Fe 3O 4and the formed Fe 3O 4@PANI core/shell particles.In this solution,the PANI grains stabilized by PVP can be adsorbed onto the particle surface (Figure 7e),which will rapidly form thin shells on the particle surfaces upon initiation.As the polymerization proceeds,large PANI nanoparticles were obtained and grew on the cores’surface to form the blackberry-like structure (Figure 7f).At last,the final compact shells can be formed (Figure 7g).Nevertheless,the reason for this morphology evolution is still not completely clear,and the detailed growth mechanism will be investigated further.
From the above analysis,it is obvious that Fe 3O 4@PANI core/shell structures with blackberry-like morphology can be suc-cessfully constructed.The magnetic properties,which are
inherited from the magnetic Fe 3O 4core particles,were measured at 300K using a superconducting quantum interference device magnetometer.As shown in the figure of magnetization (M )versus magnetic field (H )(Figure 9),the saturated magnetization value of Fe 3O 4@PANI composite spheres is 53.86emu/g at 300K.No remanence was detected for the as-prepared product.The zero coercivity and the reversible hysteresis behavior indicate the superparamagnetic nature of the particles.19Taking into account that the Fe 3O 4@PANI sample contains 66%Fe 3O 4,this gives a value of 81.7emu/g which is similar to the previous reports.14The magnetic parability of our prented core/shell-structured Fe 3O 4@PANI particles was tested in ethanol by placing an external magnetic field near the bottom of the glass bottle.A color change from black to transparent was obrved,and the black particles were attracted toward the magnet within 45s,which directly demonstrated that the obtained nanocom-posites posss magnetic properties.This feature will provide an easy and efficient avenue for parating Fe 3O 4@PANI core/shell particles from a sol or a suspension system and for carrying drugs to targeted locations under an external magnetic field.4.Conclusions
趣味问答
In summary,the prent work demonstrates a novel and facile synthetic route for the construction and synthesis of highly disperd bifunctional Fe 3O 4@PANI core/shell spheres with well-defined bl
ackberry-like morphology.The synthetic proce-dure for the well-defined core/shell structure is highly reproduc-ible.During the whole construction process,PVP molecules acted as both the linker (between the PANI and Fe 3O 4)and the stabilizer.The possible mechanism of forming the blackberry-like particles was discusd.The microspheres are shown to be superparamagnetic,which allows them to rve as ideal candidates for biomedical applications,such as nucleic acid extraction,cancer diagnosis and treatment,bionsors,and drug delivery.
Acknowledgment.This work is partly supported by an Innovative Technology Fund (CUHK6902336)from the In-novative Technology Commission,Hong Kong SAR,and a Direct Grant of Rearch (2060301)from the Chine University of Hong Kong.Professor Christopher H.K.Cheng (Biochem-istry,CUHK)is gratefully acknowledged.References and Notes
(1)Caruso,F.Ad V .Mater.2001,13,11–22.
(2)(a)Lu,Y.;Yin,Y.;Mayers,B.T.;Xia,Y.Nano Lett.2002,2,183–186.(b)Deng,Y.H.;Wang,C.C.;Hu,J.H.;Yang,W.L.;Fu,S.K.Colloid Surf.,A 2005,26,87–93.(c)Tartaj,P.;Serna,C.J.J.Am.Chem.Soc.2003,125,15754–15755.(d)Im,S.H.;Herricks,T.;Lee,Y.T.;Xia,Y.Chem.Phys.Lett.2005,401,19–23.
(3)(a)Jeong,U.;Teng,X.;Wang,Y.;Yang,H.;Xia,Y.Ad V .Mater.2007,19,33–60.(b)Lu,A.H.;Salabas,E.L.;Schueth,F.Angew.Chem.,Int.Ed.2007,46,1222–1244.
(4)(a)Tartaj,P.;Morales,M.D.P.;Veintemillas-Verdaguer,S.;Gonzalez-Carreno,T.;Serna,C.J.J.Phys.D:Appl.Phys.2003,36,R182–R197.(b)Pankhurst,Q.A.;Connolly,J.;Jones,S.K.;Dobson,J.J.Phys.D:Appl.Phys.2003,36,R167–R181.(c)Safarik,I.;Safarykova,M.J.Chromatogr.,B 1999,722,33–53.(d)Halavaara,J.;Tervahartiala,P.;Isoniemi,H.;Ho ¨ckerstedt,K.Acad.Radiol.2002,43,180–185.(e)Lubbe,A.S.;Alexiou,C.;Bergemann,C.J.Surg.Res.2001,95,200–206.(f)Xu,X.Q.;Deng,C.H.;Gao,M.X.;Yu,W.J.;Yang,P.Y.;Zhang,X.M.Ad V .Mater.2006,18,3289–3293.(g)Li,Y.;Yan,B.;Deng,C.H.;Yu,W.J.;Xu,X.Q.;Yang,P.Y.;Zhang,X.M.Proteomics 2007,7,2330–2339.(h)Levy,L.;Sahoo,Y.;Kim,K.-S.;Bergey,E.J.;Prasad,P.N.Chem.Mater.2002,14,3715–3721.(i)Yi,D.K.;Lee,S.S.;Ying,J.Y.Chem.Mater.2006,18,2459–2461.
(5)(a)Andreeva,D.V.;Gorin,D.A.;Shchukin,D.G.;Sukhorukov,G.B.Macromol.Rapid Commun.2006,27,931–936.(b)Xu,H.;Cui,
L.;
Figure 9.Room temperature magnetization curve of the as-prepared Fe 3O 4@PANI core/shell composite.
18808J.Phys.Chem.C,Vol.112,No.48,2008Xuan et al.
>维生素和矿物质
