templated synthesis of mesoporous superparamagnetic polymers

DOI: 10.1002/adfm.200700073

Templated Synthesis of Mesoporous Superparamagnetic Polymers**

By Antonio B. Fuertes,* Marta Sevilla, Sonia Álvarez, Teresa Valdés-Solís, and Pedro Tartaj

1. Introduction

The synthesis of materials with nanometre-scale architec-tures has received considerable attention in recent years. Oneof the most powerful tools for the synthesis of this kind of ma-terials is the nanocasting technique, which allows strict controlover the structural properties of the obtained products. A fun-damental part of this synthetic strategy is the use of mesopo-rous silica materials, which have been extensively employed assacrificial templates to prepare a wide variety of porous materi-als with well-controlled textural properties.[1] Whereas muchattention has been paid to the application of this syntheticroute to the preparation of porous carbons and other inorganiccompounds, only a few works have focused on the synthesis ofporous polymers. In a pioneering work, Johnston et al.[2] re-ported on the preparation of ordered mesoporous polymers byusing colloidal silica crystals as templates. Kim et al.[3] synthe-sized highly ordered three-dimensionally interconnected meso-porous polymers by using mesostructured MCM-48 and SBA-15 silica materials as templates. Lee et al.[4] employed a meso-cellular silica foam as template to fabricate a porous polymercontaining a bimodal porosity made up of two pore systems ofsizes centred at 3 nm and 17 nm. The same research group alsoreported on the fabrication of polymer capsules with a hollow

macroporous core and a mesoporous shell structure.[5] Nanopo-rous materials with entirely organic frameworks are importantfor applications in lipophilic environments where they aremore compatible with organic solvents than the commerciallyavailable inorganic supports.[6] Thus, porous polymers are ofgreat interest as supports of noble metals that are employed ascatalysts for reactions that occur in organic media.[7] These ma-terials also have great importance as adsorbents in numerousapplications including the recovery of precious metals,[8] theseparation of biomolecules[9] and the adsorption of organiccompounds.[10]

The porous polymers that support expensive catalysts (noblemetals) or contain adsorbates must be recovered and separatedafter use. However, it is often very difficult to achieve a selec-tive separation of the support/adsorbent from the reaction me-dium (liquid) due to the presence of other solid products. Oneway to overcome this problem is by magnetic separation, whichconstitutes an effective method for selectively removing a mag-netizable adsorbent. Adsorbents with magnetic properties canbe fabricated through the incorporation of magnetic nanoparti-cles within the matrix of the porous material. Recently, severalsynthetic methods have been reported for fabricating inorganicmagnetic adsorbents. Thus, magnetic porous carbons have beenobtained through the incorporation of magnetic nanoparticlesof Co,[11] Fe,[12], Ni[13], and iron oxide ferrites[14] within thepores or on the outer surface of different types of porous car-bons. Similarly, magnetic porous silica composites have beenprepared by inserting magnetic nanoparticles (Co, iron oxideferrite) via different synthetic strategies.[15] Most of these syn-thetic methods include heat treatments at relatively high tem-peratures (> 300 °C). However, these methods cannot beemployed with easily degradable polymeric materials. To over-come this difficulty we present here a novel and simple syn-thetic methodology for fabricating magnetic mesoporous poly-meric materials with a large surface area. An additionaladvantage of this method is that it allows us to prepare mag-

Adv. Funct. Mater. 2007, 17, 2321–2327 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2321

–[*] Dr. A. B. Fuertes, M. Sevilla, S. Álvarez, Dr. T. Valdés-Solís

Instituto Nacional del Carbón (CSIC)Apartado 73, 33080, Oviedo (Spain)E-mail: [email protected]. P. TartajInstituto de Ciencia de Materiales de Madrid (CSIC)Cantoblanco, 28049, Madrid (Spain)

[**] The financial support for this research work provided by the SpanishMCyT (MAT2005-00262) and CSIC-I3 (200660I192) is gratefully ac-knowledged. Supporting Information is available online from WileyInterScience or from the authors.

We present a novel synthetic strategy for fabricating superparamagnetic nanoparticles randomly dispersed in a mesoporouspolymeric matrix. This method is based on the use of mesoporous silica materials as templates. The procedure used to obtainthese mesoporous magnetic polymers consisted in: a) generating iron oxide ferrite magnetic nanoparticles (FMNP) of size∼ 7–8 nm within the pores of the silica, b) loading the porosity of the silica/FMNP composite with a polymer (Polydivinylben-zene), c) selectively removing the silica framework from the resulting silica/FMNP/polymer composite. Such magnetic porouspolymeric materials exhibit large surface areas (up to 630 m2 g–1), high pore volumes (up to 0.73 cm3 g–1) and a porosity madeup of mesopores. In this way, it is possible to obtain superparamagnetic mesoporous hybrid nanocomposites that are easilymanipulated by an external magnetic field and display different magnetic behaviours depending on the textural properties ofthe template employed.

FULL

PAPER

netic nanocomposites that display an ideal superparamagneticbehaviour and at the same time possess a magnetic momenthigh enough for the hybrid nanocomposites to be easilymanipulated by an external magnetic field. For the above men-tioned applications, the use of particles that present an idealsuperparamagnetic behaviour at room temperature is pre-ferred.[16] Moreover, the method allows us to modulate themagnetic properties of the resulting hybrid nanocomposites bysimply changing the textural properties of the sacrificial tem-plate. This synthetic method can help to clarify the interestingphysics that occurs when magnetic nanoparticles are dispersedin matrixes.[17]

2. Results and Discussion

The methodology employed to obtain the magnetic hybridnanocomposites is illustrated in Figure 1 (see Experimentalsection for details). This includes: i) the use of a porous silicathat is employed as sacrificial template, ii) the generation ofiron oxide ferrite magnetic nanoparticles (FMNP) within theporous network of the silica, iii) loading the porosity of the sili-ca/FMNP composite with a polymer synthesized in situ, iv) theselective removal of the silica framework in the resulting silica/FMNP/polymer hybrid nanocomposite. By means of this pro-cedure it is possible to obtain a porous polymer exhibiting mag-netic properties derived from the embedded FMNP.

2.1. Structural Characteristics of the Silica Used as Templatesand FMNP/Silica Composites

In order to prove the versatility of the synthetic strategy pre-sented here and to determine the influence of the initial condi-tions on the magnetic properties of the hybrid nanocomposites,we selected three mesoporous silica materials with differentstructural characteristics as sacrificial templates. Two of thesematerials were synthesized by using surfactants as structure di-recting agents, i.e., a well-ordered mesostructured SBA-15 sili-ca (S-1) and a bimodal mesoporous silica with spherical mor-phology (S-2). The other, S-3 silica, is a low-cost commercialmesoporous silica gel produced by means of simple sol-geltechniques. The textural characteristics of these materials arelisted in Table 1. They exhibit high BET surface areas, largepore volumes and a porosity made up almost exclusively of me-sopores (see Fig. S1 in the Supporting Information). As ex-pected for a SBA-15 silica, the porosity of sample S-1 consistsof highly uniform mesopores, which have a size centred at9.1 nm. The S-2 silica contains two pore systems of around2.8 nm and 27 nm, whereas the silica gel has a poorly struc-tured porosity and, in consequence, it exhibits a relativelybroad pore size distribution centred at 12 nm. These materialshardly contain any micropores as can be deduced by applyingthe as-plot method to the adsorption branch of the N2 iso-therms. The morphology of these materials is illustrated by theSEM images shown in Figure 2. The S-1 silica consists of rod-like particles with a diameter of ∼ 2 lm. The S-2 sample exhib-

its a spherical morphology with a particlediameter in the 2–4 lm range. The parti-cles of silica gel (S-3) are irregular inshape (size ∼ 5–10 lm).

The first step in our synthetic schemewas to incorporate magnetic nanoparticlesof iron oxide ferrites (magnetite, Fe3O4,and/or its oxidized form maghemite,c-Fe2O3) within the pores of the mesopo-rous silica. To achieve this we used ethyl-ene glycol as reducing agent in a similarway to that previously described by someof us to prepare superparamagnetic po-rous carbons.[14b,c] Evidence of the forma-tion of iron oxide ferrite nanoparticleswithin the pores of silica was obtained byXRD analysis (see Fig. S2(a) in Support-ing Information). The incorporation ofFMNP to the porous silica did not causeany blockage of the pores of the silica asdeduced from an analysis of the texturalproperties of the FMNP/silica composites.As an example, Figure S2(b) and S2(c)(Supporting Information) show the sorp-tion isotherm and PSD obtained for theFMNP/S-1 and FMNP/S-2 composites.These samples have high BET surfaceareas, large pore volumes and a mesopo-rous network made up of only one pore

2322 www.afm-journal.de © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Adv. Funct. Mater. 2007, 17, 2321–2327

Mesoporous silica (SBA-15)

In situ synthesis of FMNP

(iron oxide ferrite)

FMNP/Mesoporous silica

In situ

polymerization

FMNP/Silica/Polymer

Removal of the silica

framework (NaOH)

Mesoporous FMNP/Polymer

magnetic nanocomposite

Figure 1. Illustration of the synthesis procedure used for mesoporous magnetic polymeric compos-ites (Silica template: SBA-15).

FULL

PAPER

A. B. Fuertes et al./Templated Synthesis of Mesoporous Superparamagnetic Polymers

system (FMNP/S-1) or two pore systems (FMNP/S-2), whichare similar to those of S-1 and S-2 silica respectively. Thesedata reveal that, after the incorporation of FMNP, the compos-ite still retains a large and accessible porosity, which will besubsequently filled by the polymer.

2.2. Mesoporous FMNP/Polymer Magnetic Nanocomposites

Templated mesoporous FMNP/polymer replicas were ob-tained after the selective removal of the silica framework from

the FMNP/polymer/silica composite,which was carried out by means of NaOH(2 M). In this way, a porous polymeric net-work with inserted magnetic iron oxidespinel nanoparticles is obtained (ironoxide does not dissolve at a basic pH).The successful synthesis of the polymer(PDVB) was confirmed by means of infra-red spectroscopy (see Fig. S3 in the Sup-porting Information).

SEM images (Fig. 2) for the PDVB/FMNP hybrid nanocomposites reveal thatthe morphology and size of the silica tem-plates is retained in the polymeric mag-netic composites (MP-1, MP-2 and MP-3are the names of the samples derived fromS-1, S2 and S-3, respectively). Only thesample MP-2 (diameter ∼ 1.5–3 lm) ex-hibits a slight shrinkage with respect tothe corresponding S-2 silica (diameter∼ 2–4 lm). This is probably due to the factthat a portion of the large pores observedin the S-2 silica (27 nm, see Fig. S1b) par-tially collapse during their replication to apolymer. Evidence of the presence of theiron oxide ferrite phase in these hybridnanocomposites was obtained by XRDanalysis (Fig. S4 in the Supporting Infor-mation). The particle sizes of the iron ox-ide spinel nanoparticles obtained from the(311) reflection, using the Scherrer equa-tion are around 7–8 nm (Table 1). Theamount of iron oxide spinel in these com-posites ranges from 23 to 32 wt % as de-duced by thermogravimetric analysis(Table 1). Despite the presence of theseinorganic oxide particles, the FMNP/PDVB hybrid nanocomposites possesshigh BET surface areas and large porevolumes (Table 1). The sorption isotherms(Fig. 3a) contain capillary condensationsteps, which clearly reflect the existenceof a mesoporous network. The pores sizedistributions (PSD, Fig. 3b) deduced froman analysis of these isotherms confirmthat the porosity of the MP-1 and MP-3samples is made up of uniform mesopores

with sizes centred at 4.1 nm and 5.9 nm respectively. In con-trast, the PSD of the MP-2 sample indicates that the porosityof this material is made up of mesopores with sizes rangingfrom 2 nm to 20 nm. In our opinion, this broad PSD reflectsthe presence of two pore systems. One system of mesopores isgenerated from the dissolution of the silica walls (pores with asize of around 2.5 nm), whereas the other pore system (poresize > 10 nm) must correspond to the non-filled large meso-pores present in the bimodal S-2 sample. The presence of theselarge mesopores is a consequence of the fact that during syn-

Adv. Funct. Mater. 2007, 17, 2321–2327 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.afm-journal.de 2323

Table 1. Physical properties of the silica materials used as template and of the mesoporous mag-netic polymeric composites.

Material Code SBET

[m2.g–1]

Vp

[cm3.g–1]

Pore size

[nm]

Ferrite content

[wt %]

dXRD (ferrite)

[nm]

Ms [emu.g–1] Hc

[Oe]

Silica

(Template)

S-1 490 0.92 9.1 – – – –

S-2 860 2.06 2.8, 27 – – – –

S-3 340 0.84 12 – – – –

Magnetic

polymer

MP-1 510 0.49 4.1 23 7 9.8 0

MP-2 630 0.73 2–20 27 8 6.4 0

MP-3 390 0.50 5.9 32 8 15.6 0

Figure 2. SEM microphotographs of the silica samples used as templates (S-1, S-2, and S-3) and ofthe magnetic porous polymeric materials (MP-1, MP-2, and MP-3).

FULL

PAPER


thesis, in order to replicate the bimodal porosity of the S-2 sili-ca in the polymeric composite, only ∼ 65 % of the pore volumeof FMNP/S-2 was loaded with the polymeric precursor.

The TEM microphotographs (Fig. 4) show that the iron ox-ide spinel nanoparticles (dark spots) are dispersed throughoutthe polymeric matrix. In the MP-1 hybrid nanocomposite, themagnetic nanoparticles appear to form small clusters. This canbe also clearly seen in the TEM images obtained from theMP-2 sample (Fig. 4b and c). On the other hand, in the MP-3composite, the FMNPs are well-dispersed and the size quanti-

fied from TEM (∼ 8–10 nm) is in good agreement with that de-duced by XRD analysis. Moreover, the TEM images obtainedfor the MP-1 sample show that the ordered structure character-istic of SBA-15 is partially preserved in the polymeric compos-ite (Fig. 4a). This is corroborated by comparing the XRD pat-terns obtained at the low-range angles (0.5–5°) for the S-1(SBA-15) silica and the MP-1 composite (Fig. S5 in the Sup-porting Information). Thus, whereas the S-1 sample exhibitsthree well-resolved XRD peaks, which can be assigned to the(100), (110), and (200) reflections characteristic of the 2D hex-agonal space group p6mm, the MP-1 composite exhibits aXRD sharp peak at 2h = 1.05°, indicating a mesoporous struc-ture with a long-range ordering.

2.3. Magnetic Characterization of the Mesoporous FMNP/Polymer Hybrid Nanocomposites

One possible use for the hybrid nanocomposites prepared inthis work is in the magnetically-assisted separation of com-pounds from a liquid medium. We are particularly interested innanocomposites that display reversible magnetic behaviour atroom temperature.[16] Moreover, the samples prepared herecould serve as an ideal system for checking the influence of thetextural properties of the initial templates on the magneticproperties of the resulting hybrid nanocomposites. This infor-mation could be useful for drug targeting (in that case the poly-mer would be replaced by a biocompatible one). The results ofthe magnetic characterization of the nanocomposites revealthat they have a reversible magnetic behaviour (i.e., zero coer-civity field) at room temperature, as is illustrated in Figure 5a.It is well-known that nanoscale iron oxide ferrite samples havea magnetic moment that is dependent on nanoparticle size, de-gree of order and the specific surface coating or degree of in-teraction with the matrix.[18] In our samples, we observed (afternormalizing to the iron oxide content) that sample MP-2 whichhas a larger crystallite size than sample MP-1 and a similar


0

100

200

300

400

500

600

0.0 0.2 0.4 0.6 0.8 1.0

Relative pressure (p/po)

Ad

so

rbe

d v

olu

me

, (c

m3

ST

P/g

)

MP-1

MP-2

MP-3

a

0

1

2

1 10 100

Pore size (D), nm

dV

/dlo

g(D

), c

m3/g

4.1 nm

5.9 nm

b

Figure 3. a) Nitrogen sorption isotherms and b) pore size distributions of the magnetic porous polymeric materials (MP-1, MP-2, and MP-3).

50 nm

a

500 nm

b

50 nm

c

40 nm

d

Figure 4. TEM images showing the microstructure of the porous magneticpolymeric composites. The dark spots correspond to areas containingmagnetic nanoparticles. (a) MP-1, (b, c) MP-2 and (d) MP-3.

FULL

PAPER


crystallite size to sample MP-3 exhibits a lower saturation mag-netization (Ms). More specifically, the normalized Ms of sampleMP-2 is 24 emu g–1 versus 43 and 49 emu g–1 for samples MP-1and MP-3, respectively. This result could be related to the high-er degree of disorder in the ferrite nanocrystals of the MP-2

sample or more plausibly to the different degree of interactionwith the polymeric matrix. This may be a consequence of thetextural properties of sample MP-2, which are quite differentto those observed in sample MP-1 and MP-3.

It is important to examine not only the magnetic reversibilitybehaviour but also the nature of this reversibility. In otherwords we are interested in knowing whether we are dealingwith composites that present a non-interacting regime or an in-teracting superparamagnetic regime. Again our system is idealfor correlating the textural properties of the initial templateswith the possible presence of these two regimes. The non-inter-acting superparamagnetic regime is characterized by a H/Tscaling law of reduced magnetization isotherms.[17] In the tem-perature range from 200 K to RT (Fig. 5b), samples MP-1 andMP-3 present a non-interacting superparamagnetic regime(i.e., the ideal regime) which is characterized by a H/T scalinglaw while samples MP-2 do not scale with H/T. These resultstend to confirm those obtained by the TEM images (Fig. 4band c), which clearly showed the presence of aggregates ofmagnetic nanoparticles in sample MP-2. In sample MP-1,which according to TEM image (Fig. 4a), also presents someaggregates of magnetic nanoparticles, the maintenance of idealsuperparamagnetic behaviour at temperatures higher than200 K could be associated with the smaller nanocrystallite sizeof the ferrite phase (dipolar interactions scale with r6, where ris the particle radius). These results clearly demonstrate the im-portance of the textural properties of the initial templates forthe magnetic behaviour of the final nanocomposites. This resultsuggests a way to modulate the magnetic response of the mate-rials simply by changing the characteristics of the initial tem-plate.

The ability of the synthesised porous polymers to adsorb ly-pophilic substances in an organic media as well as their mag-netic separability was also examined. For this purpose, we useda lypophilic dye (Red Oil O) dissolved in n-hexane (concentra-tion ∼ 0.01 g L–1). This solution exhibits a red colour (Fig. 6a).After the addition of a small amount of the MP-2 sample, ahomogeneous black suspension is formed (Fig. 6b), whichproves that this adsorbent can be easily dispersed in a hydro-phobic medium. The dispersed MP-2 particles are rapidly at-tracted (< 1 min) by a conventional magnet placed close to thebottle, demonstrating the efficacy of magnetic separation(Fig. 6c). Moreover, magnetic separation of the adsorbentleaves a colourless solution indicating that the dye has beensuccessfully adsorbed by MP-2. UV-vis analysis (Fig. 6d) re-vealed that 96 % of dye was adsorbed by the MP-2 nanocom-posite.

3. Conclusions

In summary, we have illustrated a nanocasting route for suc-cessfully fabricating magnetically separable mesoporous hybrid(ferrite-polydivinylbenzene) nanocomposites. Such magneticnanocomposites exhibit large surface areas (up to 630 m2 g–1),high pore volumes (up to 0.73 cm3 g–1) and a porosity made upof mesopores. They exhibit a superparamagnetic behaviour,


(A)

(B)

MP3

MP1

MP2

MP3

MP-2

MP-1

M/M

s

H/T

20

10

0

-10

-20-4 -2 0 2 4

2

0

-2-0.02 -0.01 0.00 0.01 0.02

H(Teslas)

M (

em

u g

-1)

Figure 5. a) Magnetization (M) as a function of the applied magnetic field(H) for the hybrid nanocomposites. Inside is a zoom of the low-field partof the magnetization curve, in which a value of coercivity of zero is ob-served for all the samples. b) Reduced magnetization (M/Ms), measuredfor four different temperatures (200, 230, 260, 298 K), and plotted as afunction of H/T for samples MP-1, MP-2, and MP-3.

FULL

PAPER


which allows the material to be easily manipulated through anexternal magnetic field. The application of these materials asmagnetically separable adsorbents has been clearly demon-strated in this study. Moreover, easy functionalization of thepolymeric surfaces opens up a pathway for the preparation ofmagnetic polymeric composites with the desired functionalgroups that are useful for specific applications. The versatilityof the method has allowed us to obtain some useful informa-tion about the magnetic behaviour of these hybrid nanocom-posites. In particular, the fact that the magnetism of thesenanocomposites depends on the structural properties of the ini-tial template suggests a way to modulate the magnetic responseof the materials by selecting the appropriate template.

4. Experimental

Silica Templates: Three types of mesoporous silica materials were se-lected as sacrificial templates: a) an ordered mesostructured SBA-15silica (denoted as S-1), b) a bimodal mesoporous silica with a sphericalmorphology (denoted as S-2) and c) a commercial mesoporous silicagel (Aldrich, Cat No. 28851-9) (denoted as S-3). The mesostructuredSBA-15 silica was synthesized according to the procedure reported by

Yu et al. [19]. whereas the spherical bimodal mesoporous silica wasprepared according to the method described by Schulz-Ekloff et al.[20].

Incorporation of Iron Oxide Spinel Nanoparticles within the Pores ofthe Silica: Firstly, the porosity of the silica was filled with a solution ofiron nitrate in ethanol, followed by drying at 90 °C for 2 h. The amountof iron nitrate introduced was equivalent to around 12 wt % Fe in thesilica-iron oxide composite. Once the iron salt was deposited within theporosity of the silica, the sample was impregnated with ethylene glycolup to incipient wetness. The impregnated sample was then subjected toa heat treatment under nitrogen up to a temperature of 400 °C (heatingrate: 5 K min–1) and maintained at this temperature for 2 h.

Synthesis of Porous FMNP/Polymer Composites: Polydivinylbenzene(PDVB) was deposited within the pores of the silica-iron oxide com-posite. This was carried out by in situ polymerization as reported byKim et al. [21]. Briefly, a precursor solution of divinylbenzene (DVB)(Aldrich) with a free radical initiator, 1,1′-azobis(cyclohexane-carboni-trile) (ACC) (Aldrich) (DVB/ACC mol ratio: 12) was added dropwiseuntil the structural porosity of the composite was filled up to the de-sired level. Polymerization was performed by heating the impregnatedsample under nitrogen to 80 °C for 24 h. The resulting composite waswashed with chloroform and then immersed in 2 M NaOH solution(1/1: water/ethanol) at room temperature for 15 h to remove the silicatemplate. The porous polymer-FMNP composite obtained as an insolu-ble fraction was washed with distilled water and then dried in air at60 °C. Depending on the type of silica used as template, the synthesisedpolymer/FMNP composites were denoted as MP-x (x = 1, 2, or 3).

Characterization: X-ray diffraction (XRD) patterns were obtainedon a Siemens D5000 instrument operating at 40 kV and 20 mA, usingCuKa radiation (k = 0.15406 nm). The morphology of the powders wasexamined by scanning electron microscopy (SEM, Zeiss DSM 942). Ni-trogen adsorption and desorption isotherms were performed at –196 °Cin a Micromeritics ASAP 2010 volumetric adsorption system. The BETsurface area was deduced from the isotherm analysis in the relativepressure range of 0.04 to 0.20. The total pore volume was calculatedfrom the amount adsorbed at a relative pressure of 0.99. The PSD wascalculated by means of the Kruk-Jaroniec-Sayari method [22]. Themagnetic properties of the samples were recorded in a vibrating samplemagnetometer (MLVSM9 MagLab 9 T, Oxford Instrument). The satu-ration magnetization (Ms) and coercivity field values (Hc) were ob-tained from the hysteresis loops recorded up to a field value of 5 T.The amounts of polymer and iron in the composites were deduced fromthe TGA analysis using a C.I. Electronics thermogravimetric analyzer.

Received: January 15, 2007Revised: February 22, 2007

Published online: August 17, 2007

–[1] a) A. H. Lu, F. Schüth, Adv. Mater. 2006, 18, 1793. b) J. Lee, J. Kim,

T. Hyeon, Adv. Mater. 2006, 18, 2073. c) F. Schüth, Angew. Chem. Int.Ed. 2003, 42, 3604. d) H. Yang, D. Zhao, J. Mater. Chem. 2005, 15,1217. e) J. Lee, S. Han, S.; T. Hyeon, J. Mater. Chem. 2004, 14, 478.f) X. S. Zhao, F. Su, Q.Yan, W. Guo, X. Bao, L. Ly, Z. Zhou, J. Mater.Chem. 2006, 16, 637. g) Z. Y. Yuan, B. L. Su, J. Mater. Chem. 2006, 16,663. h) T. Valdés-Solís, A. B. Fuertes, Mater. Res. Bull. 2006, 41, 2187.

[2] S. A. Johnson, P. J. Ollivier, T. E. Mallouk, Science 1999, 283, 963.[3] J. Y. Kim, S. B. Yoon, F. Kooli, J. S. Yu, J. Mater. Chem. 2001, 11,

2912.[4] J. Lee, J. Kim, S. W. Kim, C. H. Shin, T. Hyeon, Chem. Commun.

2004, 562.[5] M. Kim, S. B. Yoon, K. Sohn, J. Y. Kim, C. H. Shin, T. Hyeon, J. S.

Yu, Microporous Mesoporous Mater. 2003, 63, 1.[6] R. Arshady, Adv. Mater. 1991, 3, 182.[7] a) E. Ruckestein, L. Hong, Chem. Mater. 1992, 4, 122. b) V. Smigol,

F. Svec, J. M. Frechet, Macromolecules 1993, 26, 5615. c) A. Biffis,A. A. D’Archivio, K. Jerabek, G. Schmid, B. Corain, Adv. Mater.2000, 12, 1909. d) M. Kralik, A. Biffis, J. Mol. Catal. A 2001, 177, 113.e) S. Itsuno, M. Takahashi, A. Tsuji, Macromol. Symp. 2004, 217, 191.


0.0

0.1

0.2

0.3

0.4

0.5

350 450 550 650

Wavelength, nm

Ab

so

rba

nce

A

C

d

Figure 6. a) Dye (Red oil O)/n-hexane solution, b) after dispersion of theMP-2 particles, c) after separation of the dye loaded MP-2 by a magnetand d) UV-vis spectra for the dye/n-hexane solution before and after theaddition of the MP-2 adsorbent.

FULL

PAPER


f) B. Altava, M. I. Burguete, E. Garcia-Verdugo, N. Karbass, S. V.Luis, A. Puzary, V. Sans, Tetrahedron Lett. 2006, 47, 2311.

[8] J. L. Cortina, E. Meinhardt, O. Roijals, V. Marti, React. Funct. Polym.1998, 36, 149.

[9] a) A. A. Garcia, Biotechnol. Prog. 1991, 7, 33. b) D. S. Grzegorczyk,G. Carta, Chem. Eng. Sci. 1996, 51, 819. c) A. Denizli, H. Yavuz,B. Garipcan, M. Y. Arica, J. Appl. Polym. Sci. 2000, 76, 115.

[10] J. Hradil, F. Svec, V. V. Podlesnyuk, R. M. Marutovskii, L. E. Fried-man, N. A. Klimenko, Ind. Eng. Chem. Res. 1991, 30, 1926.

[11] a) A. H. Lu, W. Schmidt, N. Matoussevitch, H. Bonnemann,B. Spliethoff, B. Tesche, E. Bill, W. Kiefer, F. Schüth, Angew. Chem.Int. Ed. 2004, 43, 4303. b) I. S. Park, M. Choi, T. W. Kim, R. Ryoo, J.Mater. Chem. 2006, 16, 3409.

[12] M. Schwickardi, S. Olejnik, E. L. Salabas, W. Schmidt, F. Schüth,Chem. Commun. 2006, 3987.

[13] P. Gorria, M. Sevilla, J. A. Blanco, A. B. Fuertes, Carbon 2006, 44,1954.

[14] a) J. Lee, S. Jin, Y. Hwang, J. G. Park, H. M. Park, T. Hyeon, Carbon2005, 43, 2536. b) A. B. Fuertes, P. Tartaj, Chem. Mater. 2006, 18, 1675.c) A. B. Fuertes, P. Tartaj, Small 2007, 3, 275.

[15] a) A. H. Lu, W. C. Li, A. Kiefer, W. Schmidt, E. Bill, G. Fink,F. Schüth, J. Am. Chem. Soc. 2004, 126, 8616. b) D. Lee, J. Lee,H. Lee, S. Jin, T. Hyeon, B. M. Kim, Adv. Synth. Catal. 2006, 348, 41.c) J. Kim, J. E. Lee, J. Lee, J. H. Yu, B. C. Kim, K. An, Y. Hwang,C. H. Shin, J. G. Park, J. Kim, T. Hyeon, J. Am. Chem. Soc. 2006, 128,

688. d) J. Kim, J. Lee, H. B. Na, B. C. Kim, J. K. Youn, J. H. Kwak,K. Moon, E. Lee, J. Kim, J. Park, A. Dohnalkova, H. G. Park, M. B.Gu, H. N. Chang, J. W. Grate, T. Hyeon, Small 2005, 1, 1203.

[16] a) Q. A. Pankhurst, J. Connolly, S. K. Jones, J. Dobson, J. Phys. D2003, 36, R167. b) P. Tartaj, Curr. Nanosci. 2006, 2, 43. c) U. Jeong,X. Teng, Y. Wang, Y. N. Xia, Adv. Mater. 2007, 19, 33.

[17] a) P. Allia, M. Coisson, P. Tiberto, F. Viani, M. Knobel, M. A. Novak,W. C. Nunes, Phys. Rev. B 2001, 64, 144 420. b) C. Binns, M. J. Maher,Q. A. Pankhurst, D. Kechrakos, K. N. Trohidou, Phys. Rev. B 2002,66, 184 413. c) P. Tartaj, T. González-Carreño, O. Bomatí-Miguel,P. Bonville, C. J. Serna, Phys. Rev. B 2004, 69, 094 401. d) J. Nogués,J. Sort, V. Langlais, V. Skumryev, S. Suriñach, J. S. Muñoz, M. D.Baró, Phys. Rep. 2005, 422, 65.

[18] a) M. P. Morales, S. Veintemillas-Verdaguer, M. I. Montero, C. J. Ser-na, A. Roig, L. Casas, B. Martinez, F. Sandiumenge, Chem. Mater.1999, 11, 3058. b) C. R. Vestal, Z. J. Zhang, J. Am. Chem. Soc. 2003,125, 9828. c) A. G. Roca, M. P. Morales, K. O’Grady, C. J. Serna,Nanotechnology 2006, 17, 2783.

[19] C. Yu, J. Fan, B. Tian, D. Zhao, G. D. Stucky, Adv. Mater. 2002, 14,1742.

[20] G. Schulz-Ekloff, J. Rathousky, A. Zukal, Int. J. Inorg. Mater. 1999, 1,97.

[21] J. Y. Kim, S. B. Yoon, F. Kooli, J. S. Yu, J. Mater. Chem. 2001, 11,2912.

[22] M. Kruk, M. Jaroniec, A. Sayari, Langmuir 1997, 13, 6267.

______________________


FULL

PAPER


templated synthesis of mesoporous superparamagnetic polymers

Documents