Composites: Part B 57 (2014) 1–7

Contents lists available at ScienceDirect

Composites: Part B

journal homepage: www.elsevier .com/locate /composi tesb

Synthesis and characterization of organic–inorganic hybrid compositesfrom poly(acrylic acid)-[3-(trimethoxysilyl)propyl methacrylate]-Al2O3

1359-8368/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.compositesb.2013.09.031

⇑ Corresponding author. Tel.: +56 412203373.E-mail addresses: c.campos@cipachile.cl (C.H. Campos), burbano@udec.cl (B.F.

Urbano), brivas@udec.cl (B.L. Rivas).

C.H. Campos a, B.F. Urbano b, B.L. Rivas b,⇑a Advanced Polymer Research Center, Beltran Mathieu 224 piso 2, Concepción 4070412, Chileb University of Concepción, Faculty of Chemistry, Department of Polymers, Edmundo Larenas 129, Concepción 4070371, Chile

a r t i c l e i n f o

Article history:Received 7 May 2013Received in revised form 19 August 2013Accepted 6 September 2013Available online 21 September 2013

Keywords:A. HybridB. Surface propertiesE. Surface treatments

a b s t r a c t

Hybrid inorganic–organic materials are promising systems for a variety of applications due to theirextraordinary properties from the combination of different building blocks. In this work, we presentthe synthesis and characterization of a hybrid material based on poly[acrylic acid] (PAA), 3-(trimethoxy-silyl)propyl methacrylate (TMPM), and aluminum oxide (Al2O3). The synthesis was carried out using atwo-step process: first, a polymerization via radical initiation, and subsequently, a sol–gel process. Thehybrids were prepared by keeping constant the amount of acrylic acid and aluminum oxide precursorbut changing the amount of TMPM. The physical and chemical properties of the hybrids were investi-gated using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 absorption (SBET), scanning electronmicroscopy (SEM), and thermogravimetric analysis (TGA). The results indicate that all of the materialswere simultaneous interpenetrating networks (SIPNs) and that the morphologies and the propertiesdepend on the amount of TMPM used. All materials showed good thermal stability, and the surface areaof the composite decreased as more TMPM was incorporated in the network.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

It is well known that organic polymers usually have some supe-rior characteristics with respect to their toughness, flexibility, andprocessability. On the other hand, inorganic materials have highheat resistance and good mechanical and optical properties. Be-cause many of the well-established materials, i.e., metals, ceramicsor plastics, cannot fulfill all technological desires, a new class ofmaterials has to be developed. With regard to tailoring new mate-rials, scientists and engineers realized early on that mixtures ofmaterials could exhibit enhanced properties compared to theirpure counterparts [1–3]. The simplest way to realize such a com-posite is to incorporate, for instance, inorganic particles into apolymeric matrix. If the interaction of the inorganic and organicphases is suitable, the material will combine the advantages ofthe inorganic material (e.g., rigidity, thermal stability) and the or-ganic polymer (e.g., flexibility, dielectric, ductility, and processabil-ity) [4–10].

The term ‘‘hybrid’’ is often used if the inorganic units are formedin situ with the polymeric matrix, for example, by the sol–gel pro-cess [11,12]. This process is similar to an organic polymerizationstarting from molecular precursors resulting in a bulk material.

Unlike many other procedures used for the synthesis of inorganicmaterials, this procedure uses mild experimental conditions, i.e.,a low reaction temperature, leading to industrial interest in theprocedure [11–16]. In particular, the silicon-based sol–gel processwas one of the major driving forces for what has become the broadfield of inorganic–organic hybrid materials [17–22]. The reason forthe special role of silicon was its good processability and the stabil-ity of the SiAC bond during the formation of the silica network,which allowed for the production of organic-modified inorganicnetworks in one step [23,24].

Kickelbick has reported different synthesis methodologies toobtain hybrid materials [25]. Particularly interesting for our workare those for interpenetrating networks (IPNs). For example, IPNsare formed if the sol–gel material is formed in the presence of anorganic polymer or vice versa. In this way, IPNs could be Class I hy-brids (materials characterized by weak interactions between thetwo phases, such as van der Waals or hydrogen bonds) or Class IIhybrids (where there is evidence of strong chemical interactions,such as covalent bonds, between the components) [11].

Depending on the strength or level of interaction, two types oforganic–inorganic hybrid materials can be obtained. Hence, to en-hance the compatibility between the components, the organic andthe inorganic components have to be modified. This modificationconsists of adding to either the organic or the inorganic componentfunctional groups similar in nature to the other constituent. Suchmodifiers are also known as coupling agents [20,26,27]. Of the in

2 C.H. Campos et al. / Composites: Part B 57 (2014) 1–7

silica-based hybrid materials, silane coupling agents are the mostused type of modifier agents. They generally have hydrolyzableand organofunctional ends. The general structure of the couplingagents can be represented as RSiX3, where the X represents thehydrolyzable groups, which are typically chloro, ethoxy or meth-oxy groups. The organo, R, group can have a variety of functional-ities chosen to meet the requirements of the polymer. Thesefunctionalities are involved in the formation of the inorganicnetwork.

Scheme 1. Schematic diagrams of simultaneous interpenetrating networks (SIPN) in theClass II with x: 0.05–0.5.

A different approach to the production of IPNs is denoted as theSIPNs (Simultaneous Interpenetrating Polymer Networks) process.In this case, the material is produced by performing the sol–gelprocess in combination with free radical polymerization of thepolymeric phase [28,29]. This approach allows for the in situ for-mation and thus the homogeneous incorporation of polymers thatnormally would not be miscible. The use of coupling agents madeit possible to observe the same beneficial effect in thermoset, i.e.,epoxy resin, cellulose matrices [18,30,31], and others matrices.

composites PAA/TMPM(x)/Al2O3 synthetized. (a) SIPN Class I, with x = 0 and (b) SIPN

Fig. 1. The powder XRD patterns of PAA/TMPM(x)/Al2O3 composites samples. (a) x:0; (b) x: 0.05; (c) x: 0.075; (d) x: 0.125; (e) x: 0.25 and (f) x: 0.50.

Fig. 2. FT-IR spectra of PAA/TMPM(x)/Al2O3 composites. Solid line, x: 0; short dotline, x: 0.05; dash line, x: 0.075; short dash dot line, x: 0.125; dash dot dot line x:0.25; dot line, x: 0.50.

Fig. 3. Curve of the nominal mole ratio between TMPM/(TMPM + AA) and the arearatio of C@O groups (ester/(ester + carboxylic)) determined by FT-IR in function ofnominal ratio of Si/(Al + Si).

Table 1Thermogravimetric parameters for the PAA/Al2O3-TMPM(x) composites.

Nominal Si/(Si + Al) mol ratio TW* (K) Td (K) Mass loss (%)

First Second

0 377 730 4.8 47.80.05 371 726 4.3 50.20.075 356 721 4.1 50.80.125 346 649 2.3 46.30.25 345 639 2.4 51.70.50 340 621 2.6 55.6

* Temperature of water desorption.

Fig. 4. Thermogravimetrical analysis for PAA/TMPM(x)/Al2O3 composites. (a) TGAand (b) DTGA. Solid line, x: 0; short dot line, x: 0.05; dash line, x: 0.075; short dashdot line, x: 0.125; dash dot dot line x: 0.25; dot line, x: 0.50.

C.H. Campos et al. / Composites: Part B 57 (2014) 1–7 3

A well-known pH-responsive polymer, poly[acrylic acid] (PAA),has typically been used as a hydrophilic segment for amphiphilicor amphipathic block copolymers with different novel properties[14,32–35]. Rivas et al. have reported the use of PAA-like polyelec-trolytes (polymers or co-polymers) with a high concentration of

ionic or ionogenic groups (having the ability to chelate or exchangemetal ions) [36–38], which can serve as carriers for some drugs inpharmaceutical applications [39,40], and that modification of themembranes through permanent hydrophilization and/or perma-nent introduction of charges can help to reduce irreversible foulingin certain applications [41].

The aim of this study was to investigate the fundamental prop-erties of SIPNs derived from PAA/Al2O3 using a coupling agent [(3-trimethoxysilyl)propyl methacrylate] (TMPM). The null hypothesestested were as follows: (i) a new type of composite can beprepared using an organosilane compound with simultaneousradical polymerization and sol–gel processes and (ii) there wouldbe differences in the resulting physical and chemical propertiesusing different Si/(Si + Al) mole ratios in the syntheses.

4 C.H. Campos et al. / Composites: Part B 57 (2014) 1–7

2. Experimental section

2.1. Materials

3-(Trimethoxysilyl)propyl methacrylate TMPM (98%), ammo-nium persulfate (APS) (>98%), 2-butanol anhydrous (>99.5%) wereobtained from Sigma–Aldrich (Saint Louis, USA). Aluminum trisec-butoxide (TSBAl) and acetylacetone (acac) were provided by Merck(Darmstadt, Germany). All the chemicals used without furtherpurification. All air-sensitive reactions were performed in a poly-merization flask using an inert N2 atmosphere. Acrylic acid (AA)was distilled in the presence of terbutylcatechol at reduced pres-sure prior to use.

2.2. IPN synthesis

An appropriate amount of TSBAl (0.03 mol) was dissolved in 2-butanol and heated to 353 K. Subsequently, 0.04 mol of acac,0.02 mol of acrylic acid, and 0.002 mol of APS were added to thereaction mixture. TMPM was added in different mol ratios ofTMPM/(TMPM + TSBAl): 0, 0.5, 0.25, 0.125, 0.075, and 0.05. Thereaction was carried out at 353 K under a N2 atmosphere and con-tinuous stirring. Once the gel point was reached, the solution wascooled to room temperature and deionized water was added overthe gel and mixed mechanically. The mixture was left for 8 h atroom temperature and later dried in a vacuum oven until a finewhite powder was obtained. All composites were washed withdeionized water under magnetic stirring for 12 h and dried at373 K. All the materials obtained were labeled as PAA/Al2O3-TMPM(x), where x corresponds to TMPM/(TMPM + TSBAl) moleratio.

2.3. Characterization

The morphological and structural characteristics of the compos-ites were measured by XRD (Rigaku D/max-2500 diffractometerwith Cu Ka radiation at 40 kV and 100 mA), FT-IR spectroscopy(Nicolet 400D in KBr matrix in the range of 4000–400/cm), SEM(JEOL JSM-6380 LV) and thermal analyzer TGA (Netzsch STA 409PC/PG [STA] at temperatures from 300 to 873 K and with a heatingrate of 10 K/min in a N2 atmosphere). The specific surface area wascalculated using the Brunauer–Emmett–Teller (BET) method. N2-BET surface areas and pore volumes were determined on aMicromeritics ASAP 2010 apparatus at 77 K. The pore size distribu-tions were obtained from the adsorption and desorption branch ofthe nitrogen isotherms by the Barrett–Joyner–Halenda (BJH)method.

Fig. 5. The N2 adsorption–desorption isotherm of PAA/TMPM(x)/Al2O3 composites.Solid line, x: 0; short dot line, x: 0.05; dash line, x: 0.075; short dash dot line, x:0.125; dash dot dot line x: 0.25; dot line, x: 0.50.

3. Results and discussion

All of the PAA/Al2O3-TMPM(x) composites synthesized weresolids, and their physical aspects changed as the TMPM content in-creased. A washing procedure was carried out to remove unreactedmonomer and impurities in the material. However, the loss of masssuggests that polymer chains of low molecular weight that slightlyinteract with the hybrid matrix were also removed. The PAA/Al2O3-TMPM(0) composite shows the lowest yield (56%); this result canbe attributed to the absence of coupling agent, leading to SIPNClass I (see Scheme 1a), where the organic and inorganic phasesinteract only through hydrogen bonds and/or electrostatic interac-tions between the AlAOH surface groups [42]. For the compositesPAA/Al2O3-TMPM(x) with x > 0, the yield increased as the TMPMcontent increased (x: 0.05–0.125, 58%; x: 2.5, 61% and x: 0.5,75%) because it acts as a crosslinking agent between the inorganicnetwork of Al2O3 and the PAA chain, leading to SIPN Class II (see

Scheme 1b), where the organic and inorganic phases interact cova-lently, in a similar way as with conventional crosslinking reagents,such as 1,4-divinylbencene and N,N-methylene-bis-acrylamide[43–45].

3.1. X-ray diffraction analysis

Fig. 1 shows the powder X-ray diffraction patterns of the solidsPAA/Al2O3-TMPM(x). The Al2O3 displays the characteristic spectralprofile of amorphous aluminates with two amorphous halos pres-ent in the 2 theta = 23 and 40� [29,42]. This typical halo resultsfrom the dispersion of the angles and bond distances betweenthe basic structural units (silicates and aluminates), which de-stroys the structure periodicity and produces a non-crystallinematerial. Slight changes in the diffraction patterns are observedaround 10� 2 theta with increasing the TMPM content. This resultconfirms the assumption that PAA hybridization occurs on the so-lid surface without changing the structural form of the Al2O3 (com-posite PAA/Al2O3-TMPM(0)), but TMPM insertion modifies theinorganic network during the syntheses.

3.2. FT-IR analysis

Fig. 2 presents the FT-IR spectra of PAA/Al2O3-TMPM(x). The ex-pected absorption bands for the aluminosilicate can be observed at1113 cm�1 (CASiAO, st). The absorption peak of the AlAO stretch-ing vibration often appears in the range of 1000–1200 cm�1. How-ever, for the present system, it could not be solved due to itsoverlap with the absorption peak of the SiAOASi stretching vibra-tion. The absorption band at 3436 cm�1 is associated with the OAHbond vibration, while the very strong band at 1532 cm�1 is attrib-uted to the C@O carboxylic stretch of PAA. The band at 1720 cm�1

corresponds to the C@O ester vibration of TMPM.Fig. 3 shows a graph of the nominal mole ratio TMPM/

(TMPM + AA) and the area ratio of C@O absorptions associatedwith the ester and carboxylic groups’ vibrations determined byFT-IR and expressed as a ratio of the form ester/(ester + carboxylic).The ratios were plotted as a function of the nominal ratio Si/(Al + Si). Both curves show the same trend, though the experimen-tal curve lies above the nominal curve. This finding suggests thatfor each hybrid, more TMPM was incorporated into the matrix thanAA monomer. This result is consistent with the washing yields

Table 2Porosity data of PAA/Al2O3-TMPM(x) composite samples.

Nominal Si/(Si + Al)mol ratio

SBET

(m2 g�1)Pore volume(cm3(STP)g�1)

Diameter pore(nm)

0 140 0.37 1000.05 74 0.21 1060.075 48 0.12 890.125 39 0.09 870.25 35 0.08 870.50 34 0.06 86

C.H. Campos et al. / Composites: Part B 57 (2014) 1–7 5

observed in Table 1, and the polymer chains that are contributingto the absorption in the FT-IR are those covalently anchored to theinorganic material by the formation of CASiAOAAl (see the in-creased vibration band at 1113 cm�1). These results demonstratethe formation of SIPN because the use of TMPM improves the pro-duction of composites with co-continuous phases.

3.3. Thermogravimetric analysis

Fig. 4 presents the TGA and DTGA curves of PAA/Al2O3-TMPM(x). The composites show two stages of degradation. Thefirst step occurs at approximately 350 K and is related to desorp-tion of water. The second step appears at higher temperatures inthe range of 620–720 K and is attributed to the degradation ofthe polymer, with the degradation ending at 780 K. On the other

Fig. 6. Scanning electronmicroscopy (SEM) photographs of PAA/TMPM(x)/Al2O3 com

hand, it is observed that the mass loss depends on the TMPM con-tent; as the TMPM content increases, the mass loss decreases. Inthis case, the thermal decomposition of the polymer occurs at ahigher temperature, which shows that PAA/Al2O3-TMPM(0) com-posites have higher thermal stability and a slower degradation ratethan PAA in all cases. However, for the composites PAA/Al2O3-TMPM(x) with x > 0.075, we observed significant changes in theTGA (see Fig. 4a) and DTGA (see Fig. 4b). Two separate tempera-tures in the mass loss steps are seen. The first step, appearing at654 K, corresponds to chemical transformations of Si compounds.In this way, TMPM is capable of giving SixCyO4�y species in thethermic treatments [23,24]. For this reason, we should not usethese results to express the polymer content in the composite.The second weight loss (at approximately 690–720 K), in differentamounts, is related to the degradation of the polymer (see Table 1).

3.4. BET surface area and pore size analysis

The N2 adsorption–desorption isotherms of PAA/Al2O3-TMPM(x) composite samples are shown in Fig. 5. The isothermsare similar to Type IV isotherms with H1-type hysteresis loops athigh relative pressures, according to the IUPAC classification,which is characteristic of amorphous and macro- and mesoporousmaterials. The specific surface areas and the pore sizes were calcu-lated using Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods, respectively. The structure data for all ofthese materials (BET surface area, total pore volume, and pore size)

posites. (a) x: 0; (b) x: 0.05; (c) x: 0.075; (d) x: 0.125; (e) x: 0.25 and (f) x: 0.50.

6 C.H. Campos et al. / Composites: Part B 57 (2014) 1–7

are summarized in Table 2. It is clear that PAA/Al2O3-TMPM(0) hasthe highest BET surface area (140 m2/g), pore volume (0.37 cm3/g)and pore size (100 nm), indicative that it was a host to PAA beforewashing. Textural properties of composites with x > 0 (see Table 2)are smaller than that of the composite PAA/Al2O3-TMPM(0). TheTMPM gives more crosslinked materials (polymeric-oxide net-work), promoting smaller cavities and decreasing SBET values.

3.5. Scanning electron microscopy (SEM)

Fig. 6 shows the scanning electron microscopy (SEM) micro-graphs of PAA/Al2O3-TMPM(x) composite samples. The SEM imagesof PAA/Al2O3-TMPM(0) show a regular distribution of PAA in thestructure of Al2O3. As the coupling agent content increases, so doesthe morphology of the composites. Therefore, it can be concludedthat the polymer distribution on the Al2O3 surfaces is uniform.All of the characterizations show that the composites are SIPNmaterials because the incorporation of TMPM promotes the forma-tion of laminar sites, which are characteristic of this type of mate-rial resins, consistent with the detected SBET results of decreasedsurface areas.

4. Conclusions

A novel polymer-inorganic hybrid material PAA-TMPM-Al2O3

was prepared using in situ radical polymerization and a sol–gelprocess with acrylic acid and oxide organometallic precursors. Thismethod is very simple and uses an inexpensive and versatile orga-nosilane; the method results in a composite with the polymers’functional groups. This new solid-based composite is a SIPN andchanges its properties when different Si mol ratios are used. TheTMPM increment in the composite shows a decrease in thermalstability and surface area as the organic fraction increases.

Acknowledgements

The authors thank FONDECYT (Grant No. 1110079), PIA (AnilloACT-130), FONDECYT Initiation (Grant No. 11121291), REDOC(MINEDUC project UCO1202 at U. de Concepción), and CIPACONICYT Regional Project R08C1002.

References

[1] Rozenberg BA, Tenneb R. Polymer-assisted fabrication of nanoparticles andnanocomposites. Prog Polym Sci 2008;33:40–112.

[2] Yang S, Liu L, Jia Z, Jia D, Luo Y. Structure and mechanical properties of rare-earth complex La-GDTC modified silica/SBR composites. Polymer2011;52:2701–10.

[3] Pyun J, Matyjaszewski K. Synthesis of nanocomposite organic/inorganic hybridmaterials using controlled/‘‘living’’ radical polymerization. Chem Mater2001;13:3436–48.

[4] Zhang F-A, Yu C-L. Acrylic emulsifier-free emulsion polymerization containinghydrophilic hydroxyl monomer in the presence or absence of nano-SiO2. EurPolym J 2007;43:1105–11.

[5] Mahajan LH, Mhaske ST. Composite microspheres of poly(o-anisidine)/TiO2.Mater Lett 2012;68:183–6.

[6] Haldorai Y, Lyoo WS, Noh SK, Shim J-J. Ionic liquid mediated synthesis of silica/polystyrene core–shell composite nanospheres by radical dispersionpolymerization. React Funct Polym 2010;70:393–9.

[7] Ke Y-C, Wu T-B, Xia Y-F. The nucleation crystallization and dispersion behaviorPETemonodisperse SiO2 composites. Polymer 2007;48:3324e3336.

[8] Mahdavian AR, Ashjari M, Makoo AB. Preparation of poly (styrene-methylmethacrylate)/SiO2 composite nanoparticles via emulsion polymerization. Aninvestigation into the compatiblization. Eur Polym J 2007;43:336–44.

[9] Krishnan NN, Henkensmeier D, Jang JH, Kim H-J, Rebbin V, Oha I-H, et al.Sulfonated poly(ether sulfone)-based silica nanocomposite membranes forhigh temperature polymer electrolyte fuel cell applications. Int J HydrogenEnergy 2011;36:7152–61.

[10] Park JT, Seo JA, Ahn SH, Kim JH, Kang SW. Surface modification of silicananoparticles with hydrophilic polymers. J Ind Eng Chem 2010;16:517–22.

[11] Wen J, Wilkes GL. Organic/inorganic hybrid network materials by the sol–gelapproach. Chem Mater 1996;8:1667–81.

[12] Corriu RJP, Leclercq D. Recent developments of molecular chemistry for sol–gelprocesses. Angew Chem Int Ed Engl 1996;35:1420–36.

[13] Chan C-K, Peng S-L, Chu I-M, Ni S-C. Effects of heat treatment on the propertiesof poly(methyl methacrylate)/silica hybrid materials prepared by sol–gelprocess. Polymer 2001;42:4189–96.

[14] Motomatsu M, Takahashi T, Nie HY, Mizutani W, Tokumoto H. Microstructurestudy of acrylic polymersilica nanocomposite surface by scanning forcemicroscopy. Polymer 1997;38:177–82.

[15] Lu Y, Yin Y, Mayers BT, Xia Y. Modifying the surface properties ofsuperparamagnetic iron oxide nanoparticles through a sol–gel approach.Nano Lett 2002;2:183–6.

[16] Wang H, Xu P, Zhong W, Shen L, Du⁄ Q. Transparent poly(methylmethacrylate)/silica/zirconia nanocomposites with excellent thermalstabilities. Polym Degrad Stab 2005;87:319–27.

[17] Salon M-CB, Belgacem MN. Competition between hydrolysis and condensationreactions of trialkoxysilanes, as a function of the amount of water and thenature of the organic group. Colloids Surf, A 2010;366:147–54.

[18] Abdelmouleh M, Boufi S, Belgacem MN, Dufresne A, Gandini A. Modification ofcellulose fibers with functionalized silanes: effect of the fiber treatment on themechanical performances of cellulose-thermoset composites. J Appl Polym Sci2005;98:974–84.

[19] Schexnailder P, Schmidt G. Nanocomposite polymer hydrogels. Colloid PolymSci 2009;287:1–11.

[20] Habekost LV, Camacho GB, Lima GS, Ogliari FA, Piva E, Moraes RR.Properties of particulate resin-luting agents with phosphate and carboxylicfunctional methacrylates as coupling agents. J Appl Polym Sci2013;127:3467–73.

[21] Xie Y, Hill CAS, Xiao Z, Militz H, Mai C. Silane coupling agents used for naturalfiber/polymer composites: a review. Composites A 2010;41:806–19.

[22] Bauer F, Gläsel H-J, Decker U, Ernst H, Freyer A, Hartmann E, et al.Trialkoxysilane grafting onto nanoparticles for the preparation of clear coatpolyacrylate systems with excellent scratch performance. Prog Org Coat2003;47:147–53.

[23] Pinho RO, Radovanovic E, Torriani IL, Yoshida IVP. Hybrid materials derivedfrom divinylbenzene and cyclic siloxane. Eur Polym J 2004;40:615–22.

[24] Schiavon MA, Redondo SUA, Pina SRO, Yoshida IVP. Investigation on kinetics ofthermal decomposition in polysiloxane networks used as precursors of siliconoxycarbide glasses. J Non-Cryst Solids 2002;304:92–100.

[25] Kickelbick G. Concepts for the incorporation of inorganic building blocks intoorganic polymers on a nanoscale. Prog Polym Sci 2003;28:83–114.

[26] Altmann S, Pfeiffer J. The hydrolysis/condensation behaviour ofmethacryloyloxyalkylfunctional alkoxysilanes: structure-reactivity relations.Monatsh Chem 2003;134:1081–92.

[27] Castellano M, Gandini A, Fabbri P, Belgacem MN. Modification of cellulosefibres with organosilanes: Under what conditions does coupling occur? JColloid Interface Sci 2004;273:505–11.

[28] Kalbasi RJ, Kolahdoozan M, Vanani SM. Preparation, characterization andcatalyst application of ternary interpenetrating networks of poly4-methylvinylpyridinium hydroxide–SiO2–Al2O3. J Solid State Chem2011;184:2009–16.

[29] Kalbasi RJ, Kolahdoozan M, Rezaei M. Synthesis and characterization ofpolyvinyl amine-SiO2-Al2O3 as a new and inexpensive organic–inorganichybrid basic catalyst. J Ind Eng Chem 2012;18(3):909–18.

[30] Pothan LA, Thomas S, Groeninckx G. The role of fibre/matrix interactions onthe dynamic mechanical properties of chemically modified banana fibre/polyester composites. Composites A 2006;37:1260–9.

[31] Salon M-CB, Gerbaud G, Abdelmouleh M, Bruzzese C, Boufi S, Belgacem MN.Studies of interactions between silane coupling agents and cellulose fiberswith liquid and solid-state NMR. Magn Reson Chem 2007;45:473–83.

[32] Cutie SS, Smith PB, Henton DE, Staples TL, Powell C. Acrylic acidpolymerization kinetics. J Polym Sci, Part B: Polym Phys 1997;35:2029–47.

[33] Ji J, Jia L, Yan L, Bangal PR. Efficient synthesis of poly(acrylic acid) in aqueoussolution via a RAFT process. J Macromol Sci, Part A: Pure Appl Chem2010;47:445–51.

[34] Loiseau J, Doe N, Suau JM, Egraz JB, Llauro MF, Ladavière C, et al. Synthesis andcharacterization of poly(acrylic acid) produced by RAFT polymerization.application as a very efficient dispersant of CaCO3, Kaolin, and TiO2.Macromolecules 2003;36:3066–77.

[35] Yu Y-Y, Chen W-C. Transparent organic–inorganic hybrid thin films preparedfrom acrylic polymer and aqueous monodispersed colloidal silica. Mater ChemPhys 2003;82:388–95.

[36] Rivas BL, Schiappacasse LN, Pereira E, Moreno-Villoslada I. Interactions ofpolyelectrolytes bearing carboxylate and/or sulfonate groups with Cu(II) andNi(II). Polymer 2004;45:1771–5.

[37] Rivas BL, Aguirre MC. Removal of As(III) and As(V) by Tin(II) compounds.Water Res 2010;44:5730–9.

[38] Rivas BL, Palencia M. Removal-concentration of pollutant metal-ions by water-soluble polymers in conjunction with double emulsion systems: a new hybridmethod of membrane-based separation. Sep Purif Technol 2011;81:435–43.

[39] Moreno-Villoslada I, Oyarzún F, Miranda V, Hess S, Rivas BL. Comparisonbetween the binding of chlorpheniramine maleate to poly(sodium 4-styrenesulfonate) and the binding to other polyelectrolytes. Polymer2005;46:7240–5.

[40] Moreno-Villoslada I, Jofré M, Miranda V, Chandía P, González R, Hess S, et al. P-Stacking of rhodamine B onto water-soluble polymers containing aromaticgroups. Polymer 2006;47:6496–500.

C.H. Campos et al. / Composites: Part B 57 (2014) 1–7 7

[41] Palencia M, Rivas BL. Adsorption of linear polymers on polyethersulfonemembranes: Contribution of divalent counterions on modifying ofhydrophilic–lipophilic balance of polyelectrolyte chain. J Membr Sci2011;372:355–65.

[42] Friederich B, Laachachi A, Ferriol M, Ruch D, Cochez M, Toniazzo M. Tentativelinks between thermal diffusivity and fire-retardant properties inpoly(methylmethacrylate) metal oxide nanocomposites. Polym Degrad Stab2010;95:1183–93.

[43] Urbano BF, Rivas BL, Martinez F, Alexandratos SD. Equilibrium and kineticstudy of arsenic sorption by water-insoluble nanocomposite resin of poly[N-

(4-vinylbenzyl)-N-methyl-d-glucamine]-montmorillonite. Chem Eng J2012;193–194:21–30.

[44] Santander P, Rivas BL, Urbano BF, _Ipek IY, Özkula G, Arda M, et al. Removal ofboron from geothermal water by a novel boron selective resin. Desalination2013;310:102–8.

[45] Urbano BF, Rivas BL, Martinez F, Alexandratos SD. Water-insoluble polymer–clay nanocomposite ion exchange resin based on N-methyl-D-glucamineligand groups for arsenic removal. React Funct Polym 2012;72(9):642–9.