Maghnite-H 1 , a Solid Catalyst for the Cationic Polymerization of a-Methylstyrene Ayat Moulkheir, Amine Harrane, Mohamed Belbachir Laboratoire de Chimie des Polyme `res, De ´partement de Chimie, Faculte ´ des Sciences, Universite ´ d’Oran Es-Senia, BP 1524 El M’naouer, 31000 Oran, Algeria Received 12 November 2007; accepted 26 January 2008 DOI 10.1002/app.28285 Published online 18 April 2008 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: The polymerization of a-methylstyrene (AMS) catalyzed by Maghnite-H 1 (Mag-H) was investigated. Mag-H is a montmorillonite sheet silicate clay, exchanged with protons. It was found that the cationic polymerization of AMS is initiated by Mag-H at ambient temperature in bulk and in solution. The effect of the amount of Mag-H, the tem- perature, and the solvent was studied. The polymerization rate increased with increase in the temperature and the pro- portion of catalyst, and it was larger in nonpolar solvents. These results indicated the cationic nature of the polymeriza- tion. It may be suggested that the polymerization is initiated by proton addition to monomer from Mag-H. Ó 2008 Wiley Periodicals, Inc. J Appl Polym Sci 109: 1476–1479, 2008 Key words: synthesis; cationic polymerization; catalysts; montmorillonite; a-methylstyrene INTRODUCTION Traditional processes for the cationic polymerization of a-methylstyrene (AMS) to poly(a-methylstyrene) [poly(AMS)] have made use of Lewis acids such as boron trifluoride or other protic acid catalyst/initia- tors, such as tetrafluorboric acid, hexafluorophos- phoric acid, and pentafluoroantimonate. 1–5 A drawback of most current art methods using cationic and Lewis acid initiators is that they require cold temperatures to control the polymerization and obtain polymers of the desired molecular weight and molecular weight distribution. 1,6–8 Recently, Hee-Jang and Dong-Ryul 9 have prepared new nanocomposites from montmorillonite and some vinylic polymers such as poly(AMS). The cationic polymerization of AMS was initiated using cationic initiator in the presence of montmoril- lonite to produce these nanocomposites. The purpose of this article is to study the cationic polymerization of AMS initiated directly by a mont- morillonitic clay called Maghnite-H 1 , a new nontoxic cationic catalyst for vinyl monomers. 10,11 Mag-H can be easily separated from the polymer product and regenerated by heating to a temperature above 1008C. 10 The effect of some factors such as the amount of the Mag-H, the temperature or the dielec- tric constant of solvent, and the mechanism of initia- tion are discussed. EXPERIMENTAL Preparation of the maghnite-H 1 The preparation of the Mag-H was carried out by using a method similar to that described by Belba- chir and coworkers. 10,11 Indeed, the raw-maghnite (20 g) was crushed for 20 min using a Prolabo ce- ramic balls grinder. It was then dried by baking at 1058C for 2 h. The maghnite was then weighed and placed in an Erlenmeyer flask together with 500 mL of distilled water. The maghnite/water mixture was stirred using a magnetic stirrer and combined with 0.25M sulfuric acid, until saturation was achieved over 2 days at room temperature, the mineral was washed with water until it became sulfate free, and then dried at 1508C. Reagents The monomer (99%; Aldrich, Paris, France) was purified by fractional distillation under reduced pressure. Methanol was dried over magnesium sul- fate. Toluene was washed with concentrated sulfuric acid and water, refluxed over sodium, and distilled. Dichloromethane, 1,4-dioxane, 1,2-dichlorobenzene, and THF (Aldrich Chemical) were used as received. Polymerization procedures The polymerization of AMS was carried out in a het- erogeneous system. Each mixture was prepared with 8.5 mmol of AMS and 0.05 g of Mag-H and were introduced in several (6–8) sealed tubes. The mixture was stirred with a magnetic stirrer under dry Correspondence to: A. Harrane (amineharrane@yahoo.fr). Journal of Applied Polymer Science, Vol. 109, 1476–1479 (2008) V V C 2008 Wiley Periodicals, Inc.