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Available online at www.sciencedirect.com

Particuology 6 (2008) 207–213

Synthesis and characterization of PMMA/Al2O3 compositeparticles by in situ emulsion polymerization

Hui Liu ∗, Hongqi Ye, Tianquan Lin, Tao ZhouCollege of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China

Received 5 December 2007; accepted 10 January 2008

bstract

In order to improve its dispersibility, superfine alumina (Al2O3) was encapsulated with poly(methyl methacrylate) (PMMA) by in situ emulsionolymerization. It was found that only when the concentration of sodium dodecyl sulfate (SDS) was much higher than its critical micelle concen-ration, could PMMA/Al2O3 composite particles with high percentage of grafting (PG) be prepared. The same results were obtained between thexperimental and stoichiometric amounts of tris(dodecylbenzenesulfonate) isopropoxide (NDZ), indicating that single-molecule-layer adsorptionad taken place between NDZ and Al O . Analysis using FTIR, TEM and XPS showed that PMMA/Al O composite particles with core–shell

2 3 2 3

tructure had been successfully synthesized by in situ emulsion polymerization. Compared to Al2O3, thermal stability and dispersibility of theomposite particles showed marked improvement.

© 2008 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. Allrights reserved.

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eywords: PMMA; Alumina; Composite particle; Encapsulation; Dispersibilit

. Introduction

In the last three decades superfine inorganic particles haveeen widely used in the field of polymer modification (Estevest al., 2005; Yang, Yoon, & Chung, 2004; Yoon, Choi, Yang, &ark, 2004). Embedding of superfine particles could improve theechanical and anti-aging properties of polymers, extending the

pplication of polymers in many domains (Capiglia, Mustarelli,uartarone, Tomasi, & Magistris, 1999). Due to its low price

nd abundant source, superfine alumina (Al2O3) has becomehe most commonly used polymeric filler (Ash et al., 2002; Benmor et al., 2000; Goyal, Tiwari, Mulik, & Negi, 2007; Tambelli

t al., 2002). However, a severe problem of superfine alumina ists agglomeration and incompatibility with organic matrix, bothestricting its efficient use (Kasprzyk-Hordern, 2004; Miyamae

Nozoye, 2005; Zheng, Zhang, Lu, Wang, & Xu, 2006). There-ore, surface treatment of superfine alumina is desirable in its

pplication, leading to a great deal of research. Alumina par-icles were treated with nonionic surfactants such as steroids,arbiturates and pilocarpine by Jansen, Treiner, Vaution, and

∗ Corresponding author. Tel.: +86 731 8876605; fax: +86 731 8879616.E-mail address: liuhui@mail.csu.edu.cn (H. Liu).

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674-2001/$ – see inside back cover © 2008 Chinese Society of Particuology and Institute of Process

oi:10.1016/j.partic.2008.01.003

uisieux (1994). Surface modifications induced by high energyeavy ions on Al2O3 were studied by means of photoelectronpectroscopy and extended X-ray absorption fine structure spec-roscopy, and the results have been interpreted in the frame ofensity of states calculations using a semiempirical tight bind-ng method (Jollet, Duraud, Noguera, Dooryhee, & Langevin,990). Ion implantation technique was applied to grafting –NH2midogen radicals onto the surface of Al2O3 bioceramic, and itas found that the implanted surface had better biocompatibilityith animal bone tissue than plain ceramic surface (Zhao, Zhai,g, Zhang, & Chen, 1999).As a powerful technique for preparing polymer/inorganic

omposite particles (Ma, Wang, Li, Chen, & Bai, 2006; Soares,morim, Souza, Oliveira, & Pereira da Silva, 2006), in situolymerization has been used to improve the dispersibility ofnorganic particles (Qi, Bao, Weng, & Huang, 2006). Amongther relevant research, nano-Al2O3 particles coated witholystyrene (PS) by emulsion polymerization were used as fillerso reinforce PS-based composites prepared by selective laser sin-ering, and the fractured surfaces of composites with such treated

anoparticles were found to be rougher than that with unfilledS and untreated composites (Zheng et al., 2006). Nanocompos-

tes of poly(ether ether ketone) (PEEK) containing nano-Al2O3ller up to 30 wt.% loading were prepared and characterized,

Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

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08 H. Liu et al. / Partic

howing good thermal stability, crystallization and coefficientf thermal expansion (Goyal et al., 2007). To improve theispersibility of silica, acrylate polymer/silica nanocompositearticles were prepared through mini-emulsion polymerizationy using methyl methacrylate/butylacrylate mixture containinghe well-dispersed nano-sized silica particles treated with 3-trimethoxysilyl)propylmeth-acrylate (MPS) (Qi, Bao, Huang,

Weng, 2006; Qi, Bao, Weng, et al., 2006). Polyanilina (PANI)rafted silica nanoparticles were prepared by in situ chemi-al oxidative graft polymerization of aniline with ammoniumeroxodisulfate (APS) on the surfaces of aminopropyl silicaanoparticles (Liu, Liu, & Xue, 2004).

There have been, however, few reports about the encapsu-ation of alumina with poly(methyl methacrylate) (PMMA).n the present work, in order to improve its dispersibility,uperfine alumina is encapsulated with a layer of PMMA, thats, PMMA/Al2O3 composite particles with core–shell structurere synthesized by in situ emulsion polymerization. The choicef PMMA is based on its remarkable mechanical properties,iocompatibility and transparency.

. Experimental

.1. Materials

Methyl methacrylate (MMA, Guangzhou Chemical Fac-ory, China) was washed with dilute alkali solution andistilled water, dried over calcium chloride and distillednder reduced pressure. Superfine alumina with averagearticle size of 200 nm (Shandong Aluminum Co. Ltd.,hina), titanium tris(dodecylbenzenesulfonate)-isopropoxide

NDZ, Nanjing Shuguang Chemical Group Co. Ltd., China)s a coupling agent, sodium dodecyl sulfate (SDS, Changshahemical Factory, China) as an emulsifier, ammonium persul-

ate (APS, Tianjin Chemicals Co. Ltd., China) as an initiator, andolyvinylpyrrolidone (PVP, Tianjin Chemicals Co. Ltd., China)s a dispersant, were all analytical grade reagents and used aseceived.

.2. Preparation of PMMA/Al2O3 composite particle

10 g MMA, 1.2 g SDS and 150 mL distilled water were addednto a 250 mL four-necked round-bottomed flask equipped withmechanical stirrer, a thermometer, a reflux condenser and a fun-el. After complete emulsification through stirring, 20 g Al2O3,.4 g PVP and 0.3 g NDZ were charged into the flask. The mix-ure was heated to 65 ◦C with nitrogen flowing, while 10 mL.15 mol/L APS aqueous solution was slowly added into theask. Then the mixture was heated to 85 ◦C and reacted forh. After reaction, the mixture was precipitated with methanolnd filtered. The cake was dried in vacuum for 24 h to obtainMMA/Al2O3 composite particles (called PMMA/Al2O3).

To determine quantitatively grafted and non-grafted PMMA

n PMMA/Al2O3, 5 g of PMMA/Al2O3 was dispersed in ace-one with ultrasonic vibration and the non-grafted PMMA wasissolved in acetone. After centrifugation at 10,000 rpm for 1 h,on-grafted PMMA was obtained by precipitating the filtrate

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y 6 (2008) 207–213

ith methanol. The cake was dried in vacuum, and PMMA-rafted Al2O3 obtained. The content of grafted PMMA inMMA-grafted Al2O3 was determined through calcination at00 ◦C for 3 h. The conversion of monomer (CM), percentagef grafting (PG) and grafting efficiency (GE) were calculatedccording to the following formulas (Liu & Guo, 2006; Liu, Ye,

Tang, 2007; Liu, Ye, & Zhang, 2007; Luna-Xavier, Guyot, &ourgeat-Lami, 2002):

M (%) = total PMMA (g)

MMA used (g)× 100, (1)

G (%) = grafted PMMA (g)

alumina used (g)× 100, (2)

E (%) = grafted PMMA (g)

total PMMA (g)× 100. (3)

.3. Characterization and testing

FTIR spectroscopy patterns were recorded on a Nico-et AVATAR360 system. The morphology of the resultingomposite particles was investigated by transmission electronicroscopy (TEM, Tecnai G2 20 ST). The surface char-

cterization was accomplished using an ESCALAB MK IIulti-functional X-ray photoelectron spectrometer (XPS) with

ass energy of 29.35 eV and an Mg K� line excitation source.he binding energy of C 1s (284.6 eV) was used as a reference.he thermal stability was characterized by PerkinElmer TGAystem from room temperature to 800 ◦C in air at a scanningate of 10 ◦C/min. The evaluation of dispersibility was carriedut according to the literature (Shi, Huang, Bao, & Weng, 2006):0 g samples were first dispersed in ethanol or tetrahydrofuranTHF) with ultrasonic vibration for 10 min, then 10 mL upperayer liquid was taken out and dried at 200 ◦C, and finally theesidual fraction (RF) was calculated according to the solid con-ent of the resulting residua.

. Results and discussion

.1. Affecting factors in the preparation of compositearticles

Since PMMA/Al2O3 composite particles are prepared byn-situ emulsion polymerization, it is necessary to control theoncentration of the emulsifier strictly. Fig. 1 shows the effect ofDS concentration on CM, PG and GE. As could be seen, there

s an evident increase in CM when SDS concentration stridesver its critical micelle concentration (CMC) of 8.7 mmol/L,mplying that SDS concentration higher than its CMC favorsolymerization of MMA. The CM is noted to be lower thanhat of the homogenous polymerization of MMA (Suzuki et al.,005), which can be explained as follows. First, due to possi-le adsorption on Al2O3, effective SDS concentration and the

umber of latex would decrease, thus preventing the increasef CM. Second, the existence of alumina prolongs the pathf primary radicals to latex particle, and reduces the initiat-ng efficiency, which is known as “cage effect” (Grebenkin &

H. Liu et al. / Particuology 6 (2008) 207–213 209

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ig. 1. Effect of SDS concentration on CM, PG and GEm(NDZ)/m(Al2O3) = 2%, m(PVP)/m(Al2O3) = 1.5%].

ol’shakov, 1999). It is also found that both PG and GE attainheir saturated values at CSDS = 26.5 mmol/L, implying that onlyhen SDS concentration was much higher than its CMC, canMMA/Al2O3 with high PG be prepared.

In order to enhance PMMA formation on the surface of alu-ina, NDZ, an ordinary titanate coupling agent is added into the

olymerization system. Fig. 2 demonstrates the effect of NDZmount on CM, PG and GE, showing that both PG and GE retainheir stable plateau at the mass ratio of m(NDZ)/m(Al2O3) ≥ 2%.ased on the hypothesis of single-molecule-layer adsorption,in, Wang, Qin, and Jin (2001) put forward the theoretical mass

atio of coupling agent/inorganic particle as

m(coupling agent)

m(inorganic particle)= 6M

ρNd2D× 100%, (4)

here the molar quality of coupling agent M = 0.376 kg/mol,ensity of inorganic particle ρ = 3.99 × 103 kg/m3, Avogadroonstant N = 6.02 × 1023, the calculated diameter of coupling

gent molecule d = 4.10 × 10−10 m, which is equal approxi-ately to the double length of Ti O bond, and the average

iameter of inorganic particle D = 200 nm = 2 × 10−7 m.

ig. 2. Effect of NDZ amount on CM, PG and GE [CSDS = 26.5 mmol/L,(PVP)/m(Al2O3) = 1.5%].

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ig. 3. Effect of PVP amount on CM, PG and GE [CSDS = 26.5 mmol/L,(NDZ)/m(Al2O3) = 2%].

Thus

m(NDZ)

m(Al2O3)

= 6 × 0.376

3.99 × 103 × 6.02 × 1023 × (4.10 × 10−10)2 × 2 × 10−7

×100%=2.8%,

howing a good agreement between experimental and theoreticalesults, and indicating that single-molecule-layer adsorption ofDZ did take place on surface of Al2O3 particles.As a commonly used dispersant, PVP plays an important role

n the synthesis of PMMA/Al2O3 composite particles, as shownn Fig. 3 as for its effect on CM, PG and GE, that is, both PG andE increase with the amount of PVP until “saturation” at a mass

atio of m(PVP)/m(Al2O3) = 1.5%. Increase in PVP amount maynhance the integration between PVP and Al2O3, decrease therobability of collision among inorganic particles, and improvehe dispersibility of reacting system.

.2. FTIR analysis

Fig. 4 presents the FTIR spectra of Al2O3, pure PMMAnd PMMA/Al2O3 composite particles, showing a broadand at 400–1000 cm−1 in the curve for alumina, wherere located the characteristic adsorption peaks of Al2O3Shek, Lai, Gu, & Lin, 1997). The vibration bands corre-ponding to PMMA (C O stretching vibration at 1731 cm−1,he aliphatic C–H stretch at 1394 and 2950 cm−1) and theharacteristic peaks of Al2O3 at 400–1000 cm−1 are alsoresent in the FTIR spectrum for composite particles. Further-

ore, the chemical shift of C O from 1731 cm−1 for pureMMA (in the absence of Al2O3) to 1709 cm−1 for com-osite particles is possibly due to chemical bonding betweenMMA and Al2O3. So it may be assumed that PMMA/Al2O3omposite particles were prepared by in situ emulsionolymerization.

210 H. Liu et al. / Particuology 6 (2008) 207–213

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ig. 4. FTIR spectra of Al2O3 (a), pure PMMA (b) and PMMA/Al2O3 com-osite particle (c).

.3. TEM analysis

Fig. 5 shows the TEM micrograms elucidating the surfaceorphology of PMMA/Al2O3 composite particles: their good

ispersibility, and the existence of a transparent film on the sur-ace of the particles. The diameter of Al2O3 is about 200 nm,nd the thickness of polymeric layer is about 10 nm. Theseesults suggest that PMMA/Al2O3 composite particles with aore–shell structure were synthesized by in situ polymerization.

To examine the relationship between the thickness of poly-eric layer (δ) and PG in the preparation, the observed value

nd calculated value of polymeric layer thickness are compared.ased on PG definition in Eq. (2), the polymer layer thicknessan be approximated as

= ρ(Al2O3) · D(Al2O3) · PG

6ρ(PMMA), (5)

here ρ(Al2O3) and ρ(PMMA) are density of Al2O3 andMMA respectively, and D(Al2O3) is the average diameter oflumina particles.

In this study, ρ(Al2O3) = 3.99, D (Al2O3) = 200 nm,(PMMA) = 1.18, and PG = 10.7%, so δ can be calculated as2 nm, which is basically consistent with the observed result inig. 5, that is, the thickness of polymeric layer of compositearticle can be predicted by formula (5).

.4. XPS analysis

Fig. 6 illustrates the XPS full-survey spectra of Al2O3 andMMA/Al2O3 composite particles and their surface elemen-

al compositions are listed in Table 1. Compared to Al2O3, the

able 1urface elemental composition of Al2O3 and PMMA/Al2O3 composite particles

amples Al (%) C (%) O (%)

l2O3 33.0 28.3 38.7MMA/Al2O3 4.1 72.4 23.5

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ig. 5. TEM micrograms of PMMA/Al2O3 composite particles withG = 10.7%.

ontents of Al, C and O for PMMA/Al2O3 composite parti-les changed from 33.0%, 28.3% and 38.7% to 4.1%, 72.4%nd 23.5%, respectively, indicating that Al2O3 was encapsulatedith a layer of PMMA.In order to clarify the role of surface chemical bond-

ng, high-resolution XPS spectra of C 1s and O 1s werecanned, and fitted through the software “XPSPEAKFIT” in theight of Lorentzian–Gaussian principle (Perruchot et al., 2004;ajagopalan & Iroh, 2003), as shown in Fig. 7(a) for Al2O3nd Fig. 7(b) for PMMA/Al2O3, respectively, while the bindingnergies and the attributions of C1s peaks are listed in Table 2, to

ndicate that the contents of C–C and C–O on the surface of com-osite particles were lower than those of Al2O3. Moreover, themergence of C O in the curve-fitting spectrum of compositearticles can also be ascribed to the encapsulation of Al2O3 by

H. Liu et al. / Particuology 6 (2008) 207–213 211

Table 2C 1s XPS analysis of Al2O3 and PMMA/Al2O3 composite particles

Samples Standard position (eV) Actual position (eV) Chemical shift (eV) Content (%) Attribution

Al2O3285.0 284.7 −0.3 68.2 C–C286.9 286.5 −0.4 31.8 C–O

PMMA/Al2O3

285.0 284.5 −0.5 53.6 C–C286.9 286.4 −0.5 30.8 C–O288.6 288.2 −0.4 15.6 C O

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ig. 6. XPS full-survey spectra of Al2O3 (a) and PMMA/Al2O3 compositearticles (b).

MMA. It is noticeable that negative chemical shifts take placen the curve-fitting spectrum, because the existence of polymereduces the outer electron density, weakens the shielding effect,nd enhances the inner electron binding energy.

Analogously, Fig. 8(a) and (b) demonstrate the high-esolution O 1s XPS spectra and curve-fitting of Al2O3 andMMA/Al2O3 composite particles, respectively, and Table 3resents the binding energies and the attributions of O1s peaks.ecrease of Al–O, increase of C–O and emergence of C O are

ssentially caused by the existence of PMMA on the surfacef Al2O3. Unexpectedly, positive chemical shifts of bindingnergies are observed in the O 1s peaks of composite parti-les, possibly due to the amorphous polymeric layer and specialore–shell structure of the composite particles.

To sum up, XPS analysis indicates that Al2O3 has been

ncapsulated with a layer of PMMA by in situ emulsion poly-erization through chemical bond. This is in good agreementith the FTIR analysis.

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able 31s XPS analysis of Al2O3 and PMMA/Al2O3 composite particles

amples Standard position (eV) Actual position (eV)

l2O3531.5 530.7533.1 532.8

MMA/Al2O3

531.5 531.6532.0 532.8533.1 533.8

ig. 7. High-resolution C 1s XPS spectrum and curve-fittings: (a) Al2O3 andb) PMMA/Al2O3 composite particles.

.5. TGA analysis

Fig. 9 displays the TGA curves of pure PMMA and

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f the two samples is due to the decomposition of PMMA.he initiating decomposition temperatures of pure PMMA andomposite particles are 300 ◦C and 400 ◦C, respectively. It is sug-

Chemical shift (eV) Content (%) Attribution

−0.8 78.8 Al–O−0.3 21.2 C–O

+0.1 46.4 Al–O+0.8 17.8 C O+0.7 35.8 C–O

212 H. Liu et al. / Particuology 6 (2008) 207–213

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ig. 8. High-resolution O 1s XPS spectrum and curve-fittings: (a) Al2O3 andb) PMMA/Al2O3 composite particles.

ested that strong chemical force has emerged between PMMAnd Al2O3, as is consistent with FTIR and XPS analyses.

.6. Evaluation of dispersibility

Residual fraction (RF) is used to evaluate the dispersibilityf the synthesized samples. The higher the RF is, the better theispersibility is (Shi et al., 2006). As shown in Fig. 10, the RF

ig. 9. TGA curves of pure PMMA (a) and PMMA/Al2O3 composite particlesb).

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Fig. 10. Residual fraction (RF) vs. standing time.

f Al2O3 in ethanol (or THF) after 6 h almost becomes zero,mplying that complete sedimentation has taken place. The RFf composite particles in ethanol (or THF) after 6 h is 45% (or5%), and remains at 20% (or 35%) even if the standing timencreases to 12 h. The existence of polymer may reduce the sur-ace energy of superfine alumina and prevent its agglomeration,ndicating that the dispersibility of PMMA/Al2O3 compositearticles has been markedly improved by in situ emulsion poly-erization.

. Conclusion

In order to improve its dispersibility, superfine alumina wasncapsulated with PMMA by in situ emulsion polymerization. Itas found that only when SDS concentration was much higher

han its critical micelle concentration, could PMMA/Al2O3 withigh PG be prepared. Good agreement was found betweenxperimental and theoretical NDZ amounts, indicating thatingle-molecule-layer adsorption took place between NDZ andl2O3. PMMA/Al2O3 composite particles with a core-shell

tructure were successfully synthesized by in situ emulsion poly-erization. FTIR and XPS showed that Al2O3 was encapsulatedithin a layer of PMMA through chemical bonding. Compared

o Al2O3, the thermal stability and dispersibility of compositearticles were markedly improved.

cknowledgements

The authors thank Q.N. Zhao from Wuhan University ofechnology for his great help in FTIR, TEM and XPS testing.hanks are also expressed to Zhang Y.C., Li Y., Chen Z.L. andang H. for their skillful experimental works.

eferences

sh, B. J., Rogers, D. F., Wiegand, C. J., Schadler, L. S., Siegel,R. W., Benicewicz, B. C., et al. (2002). Mechanical propertiesof Al2O3/polymethylmethacrylate nanocomposites. Polymer Composites,23(6), 1014–1025.

uolog

B

C

E

G

G

J

J

K

L

L

L

L

L

L

M

M

P

Q

Q

R

S

S

S

S

T

Y

Y

Z

H. Liu et al. / Partic

en Amor, S., Baud, G., Jacquet, M., Nanse, G., Fioux, P., & Nardin, M. (2000).XPS characterisation of plasma-treated and alumina-coated PMMA. AppliedSurface Science, 153(2–3), 172–183.

apiglia, C., Mustarelli, P., Quartarone, E., Tomasi, C., & Magistris, A. (1999).Effects of nanoscale SiO2 on the thermal and transport properties of solvent-free, poly(ethylene oxide) (PEO)-based polymer electrolytes. Solid StateIonics, 118(1–2), 73–79.

steves, A. C. C., Barros-Timmons, A. M., Martins, J. A., Zhang, W.,Cruz-Pinto, J., & Trindade, T. (2005). Crystallization behaviour ofnew poly(tetramethyleneterephthalamide) nanocomposites containing SiO2

fillers with distinct morphologies. Composites Part B: Engineering, 36(1),51–59.

oyal, R. K., Tiwari, A. N., Mulik, U. P., & Negi, Y. S. (2007). Novel high per-formance Al2O3/poly(ether-ether-ketone) nanocomposites for electronicsapplications. Composites Science and Technology, 67(9), 1802–1812.

rebenkin, S. Y., & Bol’shakov, B. V. (1999). Cage effects upon light irradiationon azo compounds: cis → trans isomerization in polymethyl methacry-late. Journal of Photochemistry and Photobiology A: Chemistry, 122(3),205–209.

ansen, J., Treiner, C., Vaution, C., & Puisieux, F. (1994). Surface modificationof alumina particles by nonionic surfactants: Adsorption of steroids, bar-biturates and pilocarpine. International Journal of Pharmaceutics, 103(1),19–26.

ollet, F., Duraud, J. P., Noguera, C., Dooryhee, E., & Langevin, Y. (1990).Surface modifications of crystalline SiO2 and Al2O3 induced by energeticheavy ions. Nuclear Instruments and Methods in Physical Research SectionB, 46(1), 125–127.

asprzyk-Hordern, B. (2004). Chemistry of alumina, reactions in aqueous solu-tion and its application in water treatment. Advances in Colloid and InterfaceScience, 110(1–2), 19–48.

in, Y. L., Wang, T. J., Qin, C., & Jin, Y. (2001). Surface organic modificationof SiO2 & Al2O3 coated TiO2 particles with titanate coupling reagent. ActaPhysico-Chimica Sinica, 17(2), 169–172 (in Chinese).

iu, H., Ye, H. Q., & Tang, X. D. (2007). Aluminum pigment encapsulated by insitu copolymerization of styrene and maleic acid. Applied Surface Science,254(2), 616–620.

iu, H., Ye, H. Q., & Zhang, Y. C. (2007). Preparation of PMMA grafted alu-minum powder by surface-initiated in situ polymerization. Applied SurfaceScience, 253(17), 7219–7224.

iu, P., & Guo, J. S. (2006). Polyacrylamide grafted attapulgite (PAM-ATP)via surface-initiated atom transfer radical polymerization (SI-ATRP) forremoval of Hg(II) ion and dyes. Colloids and Surfaces A: Physicochemicaland Engineering Aspects, 282–283, 498–503.

iu, P., Liu, W. M., & Xue, Q. J. (2004). In situ chemical oxidative graft poly-merization of aniline from silica nanoparticles. Materials Chemistry andPhysics, 87(1), 109–113.

una-Xavier, J., Guyot, A., & Bourgeat-Lami, E. (2002). Synthesis and charac-

terization of silica/poly (methyl methacrylate) nanocomposite latex particlesthrough emulsion polymerization using a cationic azo initiator. Journal ofColloid and Interface Science, 250(1), 82–92.

a, X. F., Wang, M., Li, G., Chen, H. Z., & Bai, R. (2006). Preparation ofpolyaniline–TiO2 composite film with in situ polymerization approach and

Z

y 6 (2008) 207–213 213

its gas-sensitivity at room temperature. Materials Chemistry and Physics,98(2–3), 241–247.

iyamae, T., & Nozoye, H. (2005). Poly(ethylene terephthalate) surface andalumina/poly(ethylene terephthalate) interface studied using sum-frequencygeneration spectroscopy. Surface Science, 587(1–2), 142–149.

erruchot, C., Khan, M. A., Kamitsi, A., Armes, S. P., Watts, J. F., Werne, T. V.,& Patten, T. E. (2004). XPS characterisation of core–shell silica–polymercomposite particles synthesised by atom transfer radical polymerisation inaqueous media. European Polymer Journal, 40(9), 2129–2141.

i, D. M., Bao, Y. Z., Huang, Z. M., & Weng, Z. X. (2006). Syn-thesis and characterization of poly(butyl acrylate)/silica poly(butylacrylate)/silica/poly(methyl methacrylate) composite particles. Journal ofApplied Polymer Science, 99, 3425–3432.

i, D. M., Bao, Y. Z., Weng, Z. X., & Huang, Z. M. (2006). Preparation ofacrylate polymer/silica nanocomposite particles with high silica encapsu-lation efficiency via miniemulsion polymerization. Polymer, 47(13), 4622–4629.

ajagopalan, R., & Iroh, J. O. (2003). Characterization ofpolyaniline–polypyrrole composite coatings on low carbon steel: AXPS and infrared spectroscopy study. Applied Surface Science, 218(1–4),58–69.

hek, C. H., Lai, J. K. L., Gu, T. S., & Lin, G. M. (1997). Transformationevolution and infrared absorption spectra of amorphous and crystalline nano-Al2O3 powders. Nanostructured Materials, 8(5), 605–610.

hi, J. M., Huang, Z. M., Bao, Y. Z., & Weng, Z. X. (2006). Preparation ofpoly(methyl methacrylate)/ultrafine CaCO3 composite particles by in-situdispersion polymerization. Journal of Chemical Engineering of ChineseUniversities, 20(1), 104–108 (in Chinese).

oares, B. G., Amorim, G. S., Souza, F. G., Oliveira, M. G., & Pereira da Silva,J. E. (2006). The in situ polymerization of aniline in nitrile rubber. SyntheticMetals, 156(2–4), 91–98.

uzuki, K., Wakatuki, Y., Shirasaki, S., Fujita, K., Kato, S., & Nomura, M.(2005). Effect of mixing ratio of anionic and nonionic emulsifiers on thekinetic behavior of methyl methacrylate emulsion polymerization. Polymer,46(16), 5890–5895.

ambelli, C. C., Bloise, A. C., Rosario, A. V., Pereira, E. C., Magon, C. J., &Donoso, J. P. (2002). Characterisation of PEO–Al2O3 composite polymerelectrolytes. Electrochimica Acta, 47(11), 1677–1682.

ang, B. D., Yoon, K. H., & Chung, K. W. (2004). Effect of TiO2 and SiO2

nanoparticles on the stability of poly(p-phenylene vinylene) precursor. Syn-thetic Metals, 143(1), 25–29.

oon, S., Choi, H. J., Yang, J. K., & Park, H. H. (2004). Comparative studybetween poly(p-phenylenevinylene) (PPV) and PPV/SiO2 nano-compositefor interface with aluminum electrode. Applied Surface Science, 237(1–4),451–456.

hao, Q., Zhai, G. J., Ng, D. H. L., Zhang, X. Z., & Chen, Z. Q. (1999). Surfacemodification of Al2O3 bioceramic by NH2

+ ion implantation. Biomaterials,

20(6), 595–599.

heng, H. Z., Zhang, J., Lu, S. Q., Wang, G. C., & Xu, Z. F. (2006). Effectof core–shell composite particles on the sintering behavior and propertiesof nano-Al2O3/polystyrene composite prepared by SLS. Materials Letters,60(9–10), 1219–1223.