research article synthesis, structural …downloads.hindawi.com/journals/jnm/2016/2462135.pdfpmma...

Research ArticleSynthesis Structural Characterization and ThermalProperties of the Poly(methylmethacrylate)120575-FeOOH HybridMaterial An Experimental and Theoretical Study

Silviana Correcirca1 Liacutevia C T Lacerda1 Maiacutera dos S Pires1 Marcus V J Rocha12

Francisco G E Nogueira3 Adilson C da Silva4 Marcio C Pereira5 Angela D B de Brito6

Elaine F F da Cunha1 and Teodorico C Ramalho17

1Department of Chemistry Federal University of Lavras No 37 37200000 Lavras MG Brazil2Department of Theoretical Chemistry Vrije Universiteit Amsterdam De Boelelaan 1083 1081 HV Amsterdam Netherlands3Institute of Chemistry of Sao Carlos University of Sao Paulo Avenue Trabalhador Sao Carlense 400 13560970 Sao Carlos SP Brazil4Institute of Exact Sciences and Biological Department of Chemistry Federal University of Ouro Preto Room 25 ICEB 3 Bauxita35400000 Ouro Preto MG Brazil5Institute of Science Engineering and Technology Federal University of the Jequitinhonha and Mucuri Valleys39803-371 Teofilo Otoni MG Brazil6Department of Physics Federal University of Lavras No 37 37200000 Lavras MG Brazil7Center for Basic and Applied Research Faculty of Informatics and Management University of Hradec Kralove50000 Hradec Kralove Czech Republic

Correspondence should be addressed to Teodorico C Ramalho teodqiuflabr

Received 31 August 2015 Revised 2 November 2015 Accepted 10 November 2015

Academic Editor Alessandro Pegoretti

Copyright copy 2016 Silviana Correa et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The 120575-FeOOHPMMA nanocomposites with 05 and 25 wt of 120575-FeOOH were prepared by grafting 3-(trimethoxysilyl)propylmethacrylate on the surface of the iron oxyhydroxide particlesThe FTIR spectra of the 120575-FeOOHPMMAnanocomposites showedthat the silanemonomers were covalently attached to the 120575-FeOOHparticles Because of the strong interaction between the PMMAand 120575-FeOOH nanoparticles the thermal stability of the 120575-FeOOHPMMA nanocomposites was improved compared to the purePMMAThe SEM analysis conferred the size agglomerate of particles regarding the morphology of samples The theoretical studyenabled a better understanding of the interaction of the polymer with the iron oxyhydroxideTheDFT-based calculations reinforcethe radical trapping mechanism of stabilization of nanocomposites that is Fe3+ species might be able to accept electrons comingfrom the organic phase that decomposes via radical unzipping The radical scavenge effect delays the weight loss of polymer

1 Introduction

Nanocomposites are part of broad family of materials calledorganic-inorganic hybrid materials The organic phase iscomprised of polymers and the inorganic phase can beconstituted of a wide variety of materials such as metalnanoparticles oxide nanoparticles nanotubes or clays [1 2]

In nanocomposites as in other organic-inorganichybrids the phases are dispersed at the molecular ornanometric level while in microcomposites or conventionalcomposites inorganic fillers are dispersed at a micrometric

scale This means that in conventional composites thephases are immiscible [3]

The use of the magnetic materials to synthesis organic-inorganic hybrids with polymer matrix has been developedto explore the physical and chemical properties The poly-mers can be modeled to afford a particular architectureand arrangement of the particles which could allow theincorporation of inorganics particles [4]

Materials that can appropriately replace living tissues arecalled biomaterials and must present physical and biologicalproperties consistent with these host tissues to stimulate an

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2016 Article ID 2462135 7 pageshttpdxdoiorg10115520162462135

2 Journal of Nanomaterials

adequate response Such property characterizes biocompati-bility [5]

The uses of these materials in controlled release drugto bone regeneration procedures are reported in studies Inkeeping with Soundrapandian and collaborators [6] poly-mers and ceramics are applied in nanomaterials for drugdelivery in the bones The carrier materials selected for drugdelivery in bones are expected to be affordable and needexhibit predictable release characteristics biologically andmechanically compatible with local bone tissue

The influence of the magnetic field on the controlledrelease of fluorescein isothiocyanate using nanoparticles ofmagnetitePMMAmdashpoly(methylmethacrylate)mdashand cobaltPMMA has been studied by Urbina and collaborators [7]The results showed a higher rate of release material with themagnetite

In this context hybrids based on PMMA and ironoxides have been studied in recent years especially withmagnetic iron oxides However themagnetic property wouldonly be guaranteed in modified polymers if there was amaximum dispersion of iron oxide on the polymeric matrixSubsequently PMMAwas considered a suitable dispersant ofmagnetite nanoparticles [8]

Among themagnetic iron oxides 120575-FeOOHhas attractedspecial attention due to its stability in biochemical media[9] 120575-FeOOH is a polymorph of several common ironoxyhydroxides with a structure that is based on a hexagonalclose-packed oxygen lattice similar to that of hematite (120572-Fe2O3) with iron occupying half of the available octahedral

interstices [9] Due to its superparamagnetic properties [10]120575-FeOOH is a potentially interesting material to be used inmodern medicine Despite its great importance surprisinglylittle detailed computational and experimental work on thissubject has appeared

Thus the current work aims to develop 120575-FeOOHPMMA hybrids characterizing their structure morphol-ogy and thermal properties by using several experimentaltechniques as well as to perform theoretical investigationsinvolving structural and electronic parameters

2 Materials and Methods

21 Synthesis of PMMA120575-FeOOH Films The synthesis of 120575-FeOOHwas carried out according to the modified proceduredescribed by Chagas and collaborators [10] It consists ofprecipitating Fe2+ alcoholic solution with NaOH followed byfast oxidation with H

2O2 enabling the direct attainment of

the 120575-FeOOHThe 3-(trimethoxysilyl)propyl methacrylate (Aldrich)

(TMSM) was used to graft the nanoparticles For that 500mgof dried nanoparticles was dispersed in a solution of 1mLof TMSM and 2mL of tetrahydrofuran (THF Aldrich)This mixture was kept in an ultrasound bath for 24 hoursat 55∘C The nanoparticles were washed three times withtoluene (Aldrich) and recuperated by centrifugation (7000 gfor 30min) then they were dried for 24 hours at 50∘C

Finally the grafted nanoparticles were dispersed by ultra-sound during 4 hours in 2mL of THF and mixed with

2015mL of methylmethacrylate (Aldrich) (MMA) 2mL ofTHF and 5mg of BPO (Benzoyl Peroxide) This mixturewas then kept under ultrasound for 2 hours Polymerizationof MMA was made by keeping the samples for 12 hours at70∘C The nanocomposites were deposited on Teflontrade sheetsand then dried under air atmosphere for 24 hours at roomtemperature The resulting free (not supported) films weredried for 12 hours at 100∘C

22 Characterization Thenanostructures of the hybrid filmswere characterized by Fourier transform infrared (FTIR)spectroscopy using Spectrum 2000 PerkinElmer FTIR mea-surements were performed in attenuated total reflexion(ATR) mode thus obtaining vibrational absorption spectraover a spectral range of 4000ndash400 cmminus1

The crystalline structure was analyzed by X-ray powderdiffraction (XRD) Data were obtained using XrsquoPert Promultipurpose X-ray diffraction (MPD) system employing CuK120572 radiation (120582 = 0154 nm) operated at 40mA and 45 kV

Scanning electron microscopy (SEM) was performed onsamples using LEO VP 435 scanning electron microscopeoperating at 20 kV

The thermogravimetric analyses were performed in trip-licate using a Mettler Toledo equipment (TGDSC1) StarSystem using 10mg of sample in the temperatures of 25 to1000∘C with a heating rate of 10∘Cminminus1 in a synthetic airatmosphere

23 Computational Details All calculations were performedwith DFT (Density Functional Theory) method using theADF-BAND 200901 program [11 12] The performance forcomputing the geometries has been done by the PBE densityfunctional In conjunction with PBE density functional theTZP basis set has been used which is a large uncontractedset of Slater-type orbitals containing diffuse functions whichis of triple-120577 quality and has been improved with one set ofpolarization function 3d on carbon and silicon 4f on ironand 2p on hydrogenThe frozen core approximationwas usedin the inner cores of O (1s) and Fe (1s2s2p) atoms

The 120575-FeOOH structure was built using the parametersbased on previous studies [13] with space group P-3m1 Ithas only Fe3+ atoms at the octahedral sites ldquo0 0 and 0rdquo andldquo0 0 and 12rdquo The positions of O and H atoms are definedby their coordinates ldquo13 23 and 02468rdquo and ldquo13 23 and051rdquo the lattices parameters 119886 = 2946 A and 119888 = 4552 AFor the potential surface energy calculation were varied thePMMA angles of 80 to 200∘ about the iron oxyhydroxide

3 Results and Discussion

31 Structural Characterization In the present work 120575-FeOOH and the grafted 120575-FeOOHTMSM samples werecharacterized with ATR infrared spectroscopy The obtainedresults are summarized in Figure 1 The ATR spectrum of 120575-FeOOH (Figure 1) shows a very strong and broad band at3265 cmminus1 that can be associated with the stretching modesof molecules water present on its surface The two bandsat 1096 cmminus1 and 908 cmminus1 correspond to Fe-O-H bending

Journal of Nanomaterials 3

(Fe-OH)

(Fe-OH)

120575-FeOOH120575-FeOOH grafted

0

(C=O)

20

40

60

80

100

ATR

()

900

3300

3000

2700

2400

2100

1800

1500

1200

3600

3900

Wavenumber (cmminus1)

Figure 1 FTIR spectra of 120575-FeOOH and grafted 120575-FeOOH

vibrations [13] The most remarkable band is located at1701 cmminus1 and it corresponds to carbonyl (C=O) vibrationson TMSM structureThe infrared spectrum of functionalized120575-FeOOH showed a band centered at 1096 cmminus1 which canbe attributed to Si-O-Fe vibrations [14 15] It suggests thatthe silane monomers were covalently bonded to 120575-FeOOHparticles It should be kept in mind however that theinfrared bands are attributed to Fe-O-H bending vibrationsin the same region Despite this feature the functionalizationoccurs in the formation of the Si-O-Fe bonding becausethe Fe-O-H bending vibration at 908 cmminus1 disappears in 120575-FeOOHTMSM infrared spectrum Probably one or two Si-OCH3groups are broken after functionalization reaction

Figure 2 represents the atomic model of 120575-FeOOHPMMAhybrid material

The loss of two or three methyl groups of TMSM ledto a new chemical bond between oxygen atoms from 120575-FeOOH and silicon The nucleophilic substitution of Fe-OHinto Si(OCH

3) can be described as

Fe-OH + Si-OCH3997888rarr Fe-O-Si + CH

3OH (1)

In the study of Pereira and collaborators [9] therewere found peaks in the X-ray diffraction pattern ldquo100rdquoldquo101rdquo ldquo102rdquo and ldquo110rdquo characteristic of 120575-FeOOHThe latticeparameters can be indexed on a hexagonal lattice with 119886 =2946 A and 119888 = 4552 A

The XRD patterns were recorded for the nanoparticlesafter grafting with TMSM molecules Figures 3(a) and 3(b)reveal the presence of peaks 2120579 = 36∘ 56∘ and 63∘ approx-imately corresponding to the ldquo100rdquo ldquo102rdquo and ldquo110rdquo to thegrafted 120575-FeOOH 05wt and 25 wt

The XRD showed bands characteristic of PMMA such asin the study of Shobhana and the peaks of 120575-FeOOH [16]confirming the presence of PMMA and 120575-FeOOH in thismaterial Because the main peaks are represented in bothXRD patterns in the second (Figure 3(b)) the peak intensityis smaller it can be interpreted by the fact that sample

has a higher percentage of feroxyhyte 25 wt Already inFigure 3(a) the intensity is large for the grafted 120575-FeOOH05wt

Figures 4(a) and 4(b) show the images obtained bySEM of surface and cross section fractured under liquidnitrogen of hybrids with 25 wt of 120575-FeOOHnanoparticlesrespectively

A general analysis of the micrographs of all samplesshows agglomerates of different sizes and with irregularblocks formats throughout the film The average size of theagglomerates was larger than 1 120583m to 30 120583m indicating abroad size distribution

32 Thermal Properties The thermal stabilities of theobtained hybrid materials were determined by thermogravi-metric analysis (TGA) and differential thermogravimetric(DTA)

Figures 5 and 6display theTGandDTAcurves of PMMA120575-FeOOH grafted with TMSM and 120575-FeOOHPMMAhybrid These TG and DTA curves indicate that the neat 120575-FeOOH and 120575-FeOOHTMSM sample weight loss occursin two and three distinct steps respectively For both ofthe materials the first step of weight loss can be attributedto the free water in the powder For neat 120575-FeOOH par-ticles about 11 weight loss is observed at 273∘C whichis due to the crystal transition of 120575-FeOOH to hematite[13]

By analyzing the 120575-FeOOH grafted with TMSM after thefirst step attributed to the free water in the powder it can berelated to another weight loss at 289∘C which is due to thesilane groups grafted on the iron oxyhydroxide surface Thegrafting process shifted the second decomposition step of 120575-FeOOH at 340∘C to higher values suggesting higher thermalstability

Concerning the thermal decomposition of PMMA thiscan take place in three stages the first step between 130 and260∘C is related to the decomposition starting at the head-to-head chain segments The second step between 260 and370∘C is attributed to first unzipping starting at unsaturatedpolymer end chains and the third step between 370 and500∘Ccorresponds to the random joining of polymeric chains[17 18]

The DTA curves shown in Figure 6 indicate that thestarting temperature of the second decomposition step isshifted to higher values for increasing 120575-FeOOH loadingwhile the end of this step is only slightly affected by 120575-FeOOH content This implies that the increasing amountof 120575-FeOOH nanoparticles delays the beginning of poly-mer unzipping However during the decomposition the 120575-FeOOH nanoparticles confer suppressing effect that seemsto be independent of their loading in the nanocompositeat least within the 05 to 25 wt range presented in thisstudy

We can also notice in Figure 6 that the maximumdegradation rate of PMMA occurs at 293∘C while increasing120575-FeOOH loading this maximum shifts toward higher tem-peratures from119879 = 378∘C for 120575-FeOOH05wt up to 389∘Cfor 120575-FeOOH 25wt


TMSM

Si

Fe

120575-FeOOHPMMA120575-FeOOH

MMA + THF + BPO

THF 55∘C24h

Figure 2 Atomic model of a 120575-FeOOH nanocrystal embedded in the PMMA

100

102110

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 8002120579

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Inte

nsity

(au

)

(a) Polymer 05 wt FeOOH

100

102 110

10 15 20 25 30 35 40 45 50 55 60 65 70 75 8052120579

0

100

200

300

400

500

600

700

800

900

1000

Inte

nsity

(au

)

(b) Polymer 25 wt FeOOH

Figure 3 Powder X-ray diffraction pattern of grafted 120575-FeOOH 05wt (a) and 25 wt (b) sample

20120583m

(a)

20120583m

(b)

Figure 4 SEM micrographs of PMMA120575-FeOOH hybrid with (a) 05 and (b) 25 wt of 120575-FeOOH

The radical trapping effect might be the responsiblefor the thermal stability improvement observed for theincreasing amount of 120575-FeOOH nanoparticles This effectwas recently demonstrated for inorganic hybridswith PMMA[19ndash22] Therefore the thermal improvement reported abovemay take place due to a similar effect that may be undergoing

in the presence of 120575-FeOOH which acts as radical trappersand accepts the unpaired electron from the radical polymerchain thus stopping or retarding the unzipping

321 120575-FeOOH Bulk For study theoretical calculations withthe relativistic effects DFTZORAPBEmethod of the surface


120575-FeOOH120575-FeOOHPMMATMSM

Mas

s los

s (

)

0

10

20

30

40

50

60

70

80

90

100

500100 150 200 250 300 350 400 450500Temperature (∘C)

05wt025wt

Figure 5 Thermogravimetric curves of pure PMMA and PMMAwith different 120575-FeOOH contents

DTA

Pure polymer120575-FeOOH 05

120575-FeOOH 25FeOOH

Temperature (∘C)100 200 300 400 500 600 700 800 900 1000

minus0010

minus0008

minus0006

minus0004

minus0002

0000

0002

Figure 6 Differential thermogravimetric (DTA) curves of 120575-FeOOH Polymer and 120575-FeOOHPMMA hybrid 05 and 25 wt

of 120575-FeOOH before the functionalization process were per-formed From the planes examined ldquo100rdquo ldquo101rdquo ldquo102rdquo andldquo110rdquo the more stable one was ldquo100rdquo

In the density of states (DOS) graphs the valence bandlocated in the region of the oxygen 2p and the conductionband situated in the region of the iron 3d (Figure 7) indicatean electron transfer from O2minus anions to Fe3+ cations

Figure 8 shows areaswith high and low electron density ingreen and red color respectivelyThe valence charge density ishigher in the volumes close to O atomsThese are preferentialregions for nucleophilic or electrophilic substitution whereFe-OH reacts with Si-OCH

3to originate Fe-O-Si bonds

3d

Fe

Fe

3d

2p

O

000

028

056

084

DO

S (a

u)

000

023

046

069

DO

S (a

u)

000

025

050

075

DO

S (a

u)

minus035 minus030 minus025 minus020 minus015 minus010 minus005 000minus040

Energy hartree


Energy hartree


Energy hartree

Figure 7 Densities of states (DOS) of octahedral Fe and O in thebulk 120575-FeOOH

322 PMMA120575-FeOOH The potential energy surface vary-ing the PMMA angle in relation to the oxide surface by angles(I) Si-C-C-C and (II) C-C-O-C from 80 to 200∘ has beendetermined This feature allowed us to evaluate the probableconformation of the monomer of the polymeric matrix closeto the surface of feroxyhyte nanoparticles Our results plottedin Figure 9 indicate that the minimum energy or most stableconformation of PMMA molecule on the 120575-FeOOH surfacelies in the range of 155ndash130∘

The 120575-FeOOH surface interferes in the PMMA anglesso that the system stability increases while angles I and IIreduce This phenomenon can be explained by attractiveelectrostatic interactions either between the positive regionsof the PMMA and the surface oxygen or between 120587-electronsof the end of the molecule and the empty orbital of ironatoms present on the surface This trend prevailed while theelectronic effects were greater than the steric effects


100

00552

000316

0000173

100e minus 005

Figure 8 Electrostatic surface contours of 120575-FeOOH bulk Red andgreen indicate volumes of low electron density and high electrondensity respectively Red = oxygen white = hydrogen and pink =iron

0

minus1000

minus2000

minus3000

minus4000

minus5000

minus6000

200

180

160

140

120

100

80

60

2001801601401201008060

Ener

gy (k

calm

ol)

II (deg)I (deg)

gtminus1000

ltminus1000

ltminus2000

ltminus3000

ltminus4000

ltminus5000

Figure 9 Surface potential energy of 120575-FeOOHPMMA as afunction of the (I) Si-C-C-C and (II) C-O-C-C angles 3D surface 11015840versus 21015840 versus energy Energy = distance weighted least squares

4 Conclusions

Thehybrid nanocomposites 120575-FeOOHPMMAwere success-fully prepared The results of SEM confirmed the dispersionof 120575-FeOOH particles in the polymer matrix

The TG analysis showed that the thermal stability of 120575-FeOOHPMMA nanocomposites is higher than that of purePMMA This trend became more evident by increasing theiron concentration

The results of FTIR indicate the existence of covalentbonding between silane monomers and atoms located on thesurface of the 120575-FeOOH nanoparticles This was confirmed

by surface charge density map which clearly showed thepresence of regions likely to perform this type of interaction

In general the computational studies coupled withexperimental characterizations allowed a better understand-ing of themorphology structure and electronic properties ofhybrid 120575-FeOOHPMMA

Conflict of Interests

All authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors thank the Brazilian agencies FAPEMIG CAPESand CNPq for funding this work They are also especiallygrateful to CNPq and CAPES for the fellowships and schol-arships provided Teodorico C Ramalho thanks also theInvited Professor position at the Center for Basic and AppliedResearch at the Czech Republic

References

[1] P Kiliaris and C D Papaspyrides ldquoPolymerlayered silicate(clay) nanocomposites an overview of flame retardancyrdquoProgress in Polymer Science vol 35 no 7 pp 902ndash958 2010

[2] F Hussain M Hojjati M Okamoto and R E Gorga ldquoReviewarticle polymer-matrix nanocomposites processing manufac-turing and application an overviewrdquo Journal of CompositeMaterials vol 40 no 17 pp 1511ndash1575 2006

[3] J Macan I Brnardic S Orlic H Ivankovic and M IvankovicldquoThermal degradation of epoxy-silica organic-inorganic hybridmaterialsrdquo Polymer Degradation and Stability vol 91 no 1 pp122ndash127 2006

[4] S Gross D Camozzo V Di Noto L Armelao and E TondelloldquoPMMA a key macromolecular component for dielectric low-K hybrid inorganic-organic polymer filmsrdquo European PolymerJournal vol 43 no 3 pp 673ndash696 2007

[5] G Toskas C Cherif R Hund et al ldquoChitosan(PEO)silicahybrid nanofibers as a potential biomaterial for bone regener-ationrdquo Carbohydrate Polymers vol 94 no 2 pp 713ndash722 2013

[6] C Soundrapandian B Sa and S Datta ldquoOrganic-inorganiccomposites for bone drug deliveryrdquo AAPS PharmSciTech vol10 no 4 pp 1158ndash1171 2009

[7] M C Urbina S Zinoveva T Miller C M Sabliov W TMonroe and C S S R Kumar ldquoInvestigation of magneticnanoparticle-polymer composites for multiple-controlled drugdeliveryrdquo Journal of Physical Chemistry C vol 112 no 30 pp11102ndash11108 2008

[8] S Kirchberg M Rudolph G Ziegmann and U A PeukerldquoNanocomposites based on technical polymers and stericallyfunctionalized soft magnetic magnetite nanoparticles synthe-sis processing and characterizationrdquo Journal of Nanomaterialsvol 2012 Article ID 670531 8 pages 2012

[9] M C Pereira E M Garcia A Candido Da Silva et alldquoNanostructured 120575-FeOOH a novel photocatalyst for watersplittingrdquo Journal of Materials Chemistry vol 21 no 28 pp10280ndash10282 2011

[10] P Chagas A C Da Silva E C Passamani et al ldquo120575-FeOOHa superparamagnetic material for controlled heat release under


ACmagnetic fieldrdquo Journal of Nanoparticle Research vol 15 no4 article 1544 2013

[11] G Te Velde F M Bickelhaupt E J Baerends et al ldquoChemistrywith ADFrdquo Journal of Computational Chemistry vol 22 no 9pp 931ndash967 2001

[12] BAND 200901 SCM Theoretical Chemistry Vrije UniversiteitAmsterdam The Netherlands 2009 httpwwwscmcom

[13] R M Cornell and U Schwertmann The Iron Oxides Wiley-VCH Weinheim Germany 2nd edition 2003

[14] U Schwertmann and H Thalmann ldquoThe influence of [Fe(II)][Si] and pH on the formation of lepidocrocite and ferrihydriteduring oxidation of aqueous FeCl

2solutionsrdquo Clay Minerals

vol 11 no 3 pp 189ndash200 1976[15] L Carlson and U Schwertmann ldquoNatural occurrence of ferox-

yhite (1205751015840-FeOOH)rdquo Clay and Clays Minerals vol 28 no 4 pp272ndash280 1980

[16] E Shobhana ldquoX-Ray diffraction and UV-visible studies ofPMMA thin filmsrdquo International Journal of Modern EngineeringResearch vol 2 no 3 pp 1092ndash1095 2012

[17] P R Westmoreland T Inguilizian and K Rotem ldquoFlamma-bility kinetics from TGADSCGCMS microcalorimetry andcomputational quantum chemistryrdquo Thermochimica Acta vol367-368 pp 401ndash405 2001

[18] T Kashiwagi A Inaba J E Brown K Hatada T Kitayamaand E Masuda ldquoEffects of weak linkages on the thermal andoxidative degradation of poly(methyl methacrylates)rdquo Macro-molecules vol 19 no 8 pp 2160ndash2168 1986

[19] P K Sahoo and R Samal ldquoFire retardancy and biodegradabilityof poly(methyl methacrylate)montmorillonite nanocompos-iterdquo Polymer Degradation and Stability vol 92 no 9 pp 1700ndash1707 2007

[20] M A Goncalves E F F da Cunha F C Peixoto and T CRamalho ldquoProbing thermal and solvent effects on hyperfineinteractions and spin relaxation rate of 120575-FeOOH(1 0 0) and[MnH

3buea(OH)]2minus toward new MRI probesrdquo Computational

and Theoretical Chemistry vol 1069 pp 96ndash104 2015[21] M A Goncalves E F F da Cunha F C Peixoto and T C

Ramalho ldquoNMR parameters and hyperfine coupling constantsof the Fe

3O4(1 0 0)-water interface implications for MRI

probesrdquo Chemical Physics Letters vol 609 pp 88ndash92 2014[22] K Chrissafis and D Bikiaris ldquoCan nanoparticles really enhance

thermal stability of polymers Part I an overview on thermaldecomposition of addition polymersrdquoThermochimica Acta vol523 no 1-2 pp 1ndash24 2011

Submit your manuscripts athttpwwwhindawicom

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CoatingsJournal of

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Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


adequate response Such property characterizes biocompati-bility [5]

The uses of these materials in controlled release drugto bone regeneration procedures are reported in studies Inkeeping with Soundrapandian and collaborators [6] poly-mers and ceramics are applied in nanomaterials for drugdelivery in the bones The carrier materials selected for drugdelivery in bones are expected to be affordable and needexhibit predictable release characteristics biologically andmechanically compatible with local bone tissue

The influence of the magnetic field on the controlledrelease of fluorescein isothiocyanate using nanoparticles ofmagnetitePMMAmdashpoly(methylmethacrylate)mdashand cobaltPMMA has been studied by Urbina and collaborators [7]The results showed a higher rate of release material with themagnetite

In this context hybrids based on PMMA and ironoxides have been studied in recent years especially withmagnetic iron oxides However themagnetic property wouldonly be guaranteed in modified polymers if there was amaximum dispersion of iron oxide on the polymeric matrixSubsequently PMMAwas considered a suitable dispersant ofmagnetite nanoparticles [8]

Among themagnetic iron oxides 120575-FeOOHhas attractedspecial attention due to its stability in biochemical media[9] 120575-FeOOH is a polymorph of several common ironoxyhydroxides with a structure that is based on a hexagonalclose-packed oxygen lattice similar to that of hematite (120572-Fe2O3) with iron occupying half of the available octahedral

interstices [9] Due to its superparamagnetic properties [10]120575-FeOOH is a potentially interesting material to be used inmodern medicine Despite its great importance surprisinglylittle detailed computational and experimental work on thissubject has appeared

Thus the current work aims to develop 120575-FeOOHPMMA hybrids characterizing their structure morphol-ogy and thermal properties by using several experimentaltechniques as well as to perform theoretical investigationsinvolving structural and electronic parameters

2 Materials and Methods

21 Synthesis of PMMA120575-FeOOH Films The synthesis of 120575-FeOOHwas carried out according to the modified proceduredescribed by Chagas and collaborators [10] It consists ofprecipitating Fe2+ alcoholic solution with NaOH followed byfast oxidation with H

2O2 enabling the direct attainment of

the 120575-FeOOHThe 3-(trimethoxysilyl)propyl methacrylate (Aldrich)

(TMSM) was used to graft the nanoparticles For that 500mgof dried nanoparticles was dispersed in a solution of 1mLof TMSM and 2mL of tetrahydrofuran (THF Aldrich)This mixture was kept in an ultrasound bath for 24 hoursat 55∘C The nanoparticles were washed three times withtoluene (Aldrich) and recuperated by centrifugation (7000 gfor 30min) then they were dried for 24 hours at 50∘C

Finally the grafted nanoparticles were dispersed by ultra-sound during 4 hours in 2mL of THF and mixed with

2015mL of methylmethacrylate (Aldrich) (MMA) 2mL ofTHF and 5mg of BPO (Benzoyl Peroxide) This mixturewas then kept under ultrasound for 2 hours Polymerizationof MMA was made by keeping the samples for 12 hours at70∘C The nanocomposites were deposited on Teflontrade sheetsand then dried under air atmosphere for 24 hours at roomtemperature The resulting free (not supported) films weredried for 12 hours at 100∘C

22 Characterization Thenanostructures of the hybrid filmswere characterized by Fourier transform infrared (FTIR)spectroscopy using Spectrum 2000 PerkinElmer FTIR mea-surements were performed in attenuated total reflexion(ATR) mode thus obtaining vibrational absorption spectraover a spectral range of 4000ndash400 cmminus1

The crystalline structure was analyzed by X-ray powderdiffraction (XRD) Data were obtained using XrsquoPert Promultipurpose X-ray diffraction (MPD) system employing CuK120572 radiation (120582 = 0154 nm) operated at 40mA and 45 kV

Scanning electron microscopy (SEM) was performed onsamples using LEO VP 435 scanning electron microscopeoperating at 20 kV

The thermogravimetric analyses were performed in trip-licate using a Mettler Toledo equipment (TGDSC1) StarSystem using 10mg of sample in the temperatures of 25 to1000∘C with a heating rate of 10∘Cminminus1 in a synthetic airatmosphere

23 Computational Details All calculations were performedwith DFT (Density Functional Theory) method using theADF-BAND 200901 program [11 12] The performance forcomputing the geometries has been done by the PBE densityfunctional In conjunction with PBE density functional theTZP basis set has been used which is a large uncontractedset of Slater-type orbitals containing diffuse functions whichis of triple-120577 quality and has been improved with one set ofpolarization function 3d on carbon and silicon 4f on ironand 2p on hydrogenThe frozen core approximationwas usedin the inner cores of O (1s) and Fe (1s2s2p) atoms

The 120575-FeOOH structure was built using the parametersbased on previous studies [13] with space group P-3m1 Ithas only Fe3+ atoms at the octahedral sites ldquo0 0 and 0rdquo andldquo0 0 and 12rdquo The positions of O and H atoms are definedby their coordinates ldquo13 23 and 02468rdquo and ldquo13 23 and051rdquo the lattices parameters 119886 = 2946 A and 119888 = 4552 AFor the potential surface energy calculation were varied thePMMA angles of 80 to 200∘ about the iron oxyhydroxide

3 Results and Discussion

31 Structural Characterization In the present work 120575-FeOOH and the grafted 120575-FeOOHTMSM samples werecharacterized with ATR infrared spectroscopy The obtainedresults are summarized in Figure 1 The ATR spectrum of 120575-FeOOH (Figure 1) shows a very strong and broad band at3265 cmminus1 that can be associated with the stretching modesof molecules water present on its surface The two bandsat 1096 cmminus1 and 908 cmminus1 correspond to Fe-O-H bending


(Fe-OH)

(Fe-OH)


0

(C=O)

20

40

60

80

100

ATR

()

900

3300

3000

2700

2400

2100

1800

1500

1200

3600

3900








3OH (1)














TMSM

Si

Fe


MMA + THF + BPO

THF 55∘C24h


100

102110

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 8002120579

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Inte

nsity

(au

)


100

102 110

10 15 20 25 30 35 40 45 50 55 60 65 70 75 8052120579

0

100

200

300

400

500

600

700

800

900

1000

Inte

nsity

(au

)



20120583m

(a)

20120583m

(b)







Mas

s los

s (

)

0

10

20

30

40

50

60

70

80

90

100

500100 150 200 250 300 350 400 450500Temperature (∘C)

05wt025wt


DTA



Temperature (∘C)100 200 300 400 500 600 700 800 900 1000

minus0010

minus0008

minus0006

minus0004

minus0002

0000

0002






3d

Fe

Fe

3d

2p

O

000

028

056

084

DO

S (a

u)

000

023

046

069

DO

S (a

u)

000

025

050

075

DO

S (a

u)


Energy hartree


Energy hartree


Energy hartree





100

00552

000316

0000173

100e minus 005


0

minus1000

minus2000

minus3000

minus4000

minus5000

minus6000

200

180

160

140

120

100

80

60

2001801601401201008060

Ener

gy (k

calm

ol)

II (deg)I (deg)

gtminus1000

ltminus1000

ltminus2000

ltminus3000

ltminus4000

ltminus5000


4 Conclusions








Acknowledgments


References






































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(Fe-OH)

(Fe-OH)


0

(C=O)

20

40

60

80

100

ATR

()

900

3300

3000

2700

2400

2100

1800

1500

1200

3600

3900








3OH (1)














TMSM

Si

Fe


MMA + THF + BPO

THF 55∘C24h


100

102110

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 8002120579

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Inte

nsity

(au

)


100

102 110

10 15 20 25 30 35 40 45 50 55 60 65 70 75 8052120579

0

100

200

300

400

500

600

700

800

900

1000

Inte

nsity

(au

)



20120583m

(a)

20120583m

(b)







Mas

s los

s (

)

0

10

20

30

40

50

60

70

80

90

100

500100 150 200 250 300 350 400 450500Temperature (∘C)

05wt025wt


DTA



Temperature (∘C)100 200 300 400 500 600 700 800 900 1000

minus0010

minus0008

minus0006

minus0004

minus0002

0000

0002






3d

Fe

Fe

3d

2p

O

000

028

056

084

DO

S (a

u)

000

023

046

069

DO

S (a

u)

000

025

050

075

DO

S (a

u)


Energy hartree


Energy hartree


Energy hartree





100

00552

000316

0000173

100e minus 005


0

minus1000

minus2000

minus3000

minus4000

minus5000

minus6000

200

180

160

140

120

100

80

60

2001801601401201008060

Ener

gy (k

calm

ol)

II (deg)I (deg)

gtminus1000

ltminus1000

ltminus2000

ltminus3000

ltminus4000

ltminus5000


4 Conclusions








Acknowledgments


References






































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




TMSM

Si

Fe


MMA + THF + BPO

THF 55∘C24h


100

102110

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 8002120579

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Inte

nsity

(au

)


100

102 110

10 15 20 25 30 35 40 45 50 55 60 65 70 75 8052120579

0

100

200

300

400

500

600

700

800

900

1000

Inte

nsity

(au

)



20120583m

(a)

20120583m

(b)







Mas

s los

s (

)

0

10

20

30

40

50

60

70

80

90

100

500100 150 200 250 300 350 400 450500Temperature (∘C)

05wt025wt


DTA



Temperature (∘C)100 200 300 400 500 600 700 800 900 1000

minus0010

minus0008

minus0006

minus0004

minus0002

0000

0002






3d

Fe

Fe

3d

2p

O

000

028

056

084

DO

S (a

u)

000

023

046

069

DO

S (a

u)

000

025

050

075

DO

S (a

u)


Energy hartree


Energy hartree


Energy hartree





100

00552

000316

0000173

100e minus 005


0

minus1000

minus2000

minus3000

minus4000

minus5000

minus6000

200

180

160

140

120

100

80

60

2001801601401201008060

Ener

gy (k

calm

ol)

II (deg)I (deg)

gtminus1000

ltminus1000

ltminus2000

ltminus3000

ltminus4000

ltminus5000


4 Conclusions








Acknowledgments


References






































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Mas

s los

s (

)

0

10

20

30

40

50

60

70

80

90

100

500100 150 200 250 300 350 400 450500Temperature (∘C)

05wt025wt


DTA



Temperature (∘C)100 200 300 400 500 600 700 800 900 1000

minus0010

minus0008

minus0006

minus0004

minus0002

0000

0002






3d

Fe

Fe

3d

2p

O

000

028

056

084

DO

S (a

u)

000

023

046

069

DO

S (a

u)

000

025

050

075

DO

S (a

u)


Energy hartree


Energy hartree


Energy hartree





100

00552

000316

0000173

100e minus 005


0

minus1000

minus2000

minus3000

minus4000

minus5000

minus6000

200

180

160

140

120

100

80

60

2001801601401201008060

Ener

gy (k

calm

ol)

II (deg)I (deg)

gtminus1000

ltminus1000

ltminus2000

ltminus3000

ltminus4000

ltminus5000


4 Conclusions








Acknowledgments


References






































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




100

00552

000316

0000173

100e minus 005


0

minus1000

minus2000

minus3000

minus4000

minus5000

minus6000

200

180

160

140

120

100

80

60

2001801601401201008060

Ener

gy (k

calm

ol)

II (deg)I (deg)

gtminus1000

ltminus1000

ltminus2000

ltminus3000

ltminus4000

ltminus5000


4 Conclusions








Acknowledgments


References






































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article synthesis, structural …downloads.hindawi.com/journals/jnm/2016/2462135.pdfpmma...

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