Synthesis and Thermal Behavior of Poly(methyl methacrylate)/Maghnia Bentonite Nanocomposite Prepared at Room Temperature via In Situ Polymerization Initiated by a New Ni(II)a-Benzoinoxime Complex Kamel Ouaad, 1,2 Saı ¨d Djadoun, 1 Hafida Ferfera-Harrar, 1 Nicolas Sbirrazzuoli, 3 Luc Vincent 3 1 Laboratoire des Mate ´riaux Polyme `res, Faculte ´ de Chimie, USTHB, BP 32, El-Alia, Bab-Ezzouar, Algiers 16111, Algeria 2 De ´partement de Chimie, Faculte ´ des Sciences, Universite ´ M’Hamed Bouguera, Avenue de L’Inde ´pendance, Boumerde `s 35000, Algeria 3 Laboratoire Chimie des Mate ´riaux Organiques et Me ´talliques, Institut de Chimie de Nice, Faculte ´ des Sciences, Universite ´ de Nice Sophia Antipolis, Nice Cedex-2 06108, France Received 17 January 2010; accepted 25 May 2010 DOI 10.1002/app.32872 Published online 24 September 2010 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate)/clay nanocomposite (PMMA/ OBT) were successfully prepared in dioxan at room tem- perature via in situ radical polymerization initiated by a new Ni(II)a- Benzoinoxime complex as a single compo- nent in presence of 3% by weight of an organically modi- fied bentonite (OBT) (originated from Maghnia, Algeria) and characterized by FTIR, 1 H-NMR and viscometry. Mainly intercalated and partially exfoliated PMMA/OBT nanocomposite was elaborated and evidenced by X-Ray diffraction (XRD) and transmission electron microscopy (TEM). The intrinsic viscosity of PMMA/OBT nanocompo- site is much higher than the one of pure PMMA prepared under the same conditions. Differential scanning calorime- try (DSC) displayed an increase of 10  C in the glass tran- sition temperature of the elaborated PMMA/OBT nanocomposite relative to the one of pure PMMA. More- over, the TGA analysis confirms a significant improve- ment of the thermal stability of PMMA/OBT nanocomposite compared to virgin PMMA: the onset deg- radation temperature of the nanocomposite, carried out under nitrogen atmosphere, increased by more than 45  C. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 3227–3233, 2011 Key words: poly(methyl methacrylate); nanocomposite; in situ polymerization; Ni(II)a- benzoinoxime complex; thermal stability INTRODUCTION Extensive research has been carried out in the last decades on the elaboration of polymer-clay nano- composites involving both thermoplastics and ther- mosets. 1–4 Many of these polymer-clay nanocompo- sites show significant improvements mainly in their mechanical, barrier and thermal properties com- pared to micro and macro composites. 5–8 Poly(methyl methacrylate) (PMMA) is one of the largely investigated thermoplastic-clay nanocompo- sites. Various methods of preparation of PMMA/ Clay nanocomposites that produced intercalated or exfoliated structures of improved properties have been reported. 9–11 Significant progresses are recently made in the field of transition metal complexes as catalysts for olefin polymerization. 12–14 However, their combina- tion with organically modified clay have attracted less interest in the preparation of polymer/clay nanocomposites via coordination polymerization owing to its challenging sensitivity problem to mois- ture and tiny impurities. Several approaches were therefore developed to achieve this kind of nano- composites. Tudor et al. 15 first treated the layered silicate with a large amount of methylaluminoxane (MAO) and then immobilized the metallocene cata- lyst on the surface of MAO-modified silicates nano- whiskers to subsequently initiate the polymerization of ethylene. Mariott et al. 16 prepared stereochemi- cally controlled PMMA-exfoliated silicate in which metallocene cationic complexes were effectively anchored inside the silicate galleries via a noncation- exchange approach involving protonolysis. He et al. 17 combined a traditional Ziegler–Natta catalyst with modified-montmorillonite to prepare exfoliated Correspondence to: S. Djadoun (matpolylab@yahoo.fr). Journal of Applied Polymer Science, Vol. 119, 3227–3233 (2011) V C 2010 Wiley Periodicals, Inc.