- Email: [email protected]
Ring opening polymerization of oxetane by the use of a montmorillonite clay as catalyst
Materials Letters 61 (2007) 3555 – 3558 www.elsevier.com/locate/matlet
Ring opening polymerization of oxetane by the use of a montmorillonite clay as catalyst Amine Harrane ⁎, Nacéra Naar, Mohammed Belbachir Laboratoire de Chimie des Polymères, Département de Chimie, Faculté des Sciences, Université d'Oran Es-Senia, BP No 1524 El M'Naouar, 31000 Oran, Algeria Received 21 June 2006; accepted 23 November 2006 Available online 15 December 2006
Abstract Maghnite-H+ was found to be an effective solid catalyst for the ring opening polymerization of oxetane. Maghnite-H+ is a proton exchanged montmorillonite clay. Effect of weight ratio of initiator/monomer and reaction time on the conversion of monomer and the molecular weight is investigated. Increasing maghnite-H+ proportion produced an increase in oxetane conversion and a decrease in Mn. A cationic mechanism for the reaction was proposed. © 2006 Elsevier B.V. All rights reserved. Keywords: Montmorillonite; Maghnite; Ring opening polymerization; Oxetane; Polyoxetane
1. Introduction Products obtained from oxetanes have attracted much attention, which can be used for adhesives instead of those from oxiranes [1–4]. The ring opening polymerization of oxetanes has been usually conducted by the use of cationic species [5–8], and the uses of various solid materials to induce oxetanes polymerization have been also well known [9,10]. In the solid catalysts, several derivatives based on silica such as aluminium minerals and zeolites are reported. Minerals and zeolites are reported to be effective for the ring opening reaction leading to 1,2-difunctionalized compounds from oxiranes [11–14]. Recently, in polymer synthesis, the silica derivatives have been employed for the well-defined ring opening polymerization of 1,2-epoxide and lactones [15–18]. The enhancement of such ring opening reaction is explained by, Brønsted and Lewis acidity with an appropriate reaction environment provided by the catalysts. In the present work, cationic ring opening polymerization of oxetane was induced by maghnite-H+ [19], an eco-catalyst proton exchanged montmorillonite clay. This new non-toxic cationic catalyst has exhibited higher efficiency via the polymerization of vinylic and heterocyclic monomers [20–24]. ⁎ Corresponding author. E-mail address: [email protected] (A. Harrane). 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.11.118
Techniques such as 1H NMR, 13C NMR, and IR, were used to characterize the products of the reaction. The effects of catalyst/ monomer weight ratio and time on monomer conversion and polymer average molecular weight were also examined. 2. Experimental 2.1. Materials Oxetane (Aldrich Chemical) was distilled under argon atmosphere before use. Dichloromethane was dried over CaH2 and distilled on the day of experiment. Raw-maghnite: Algerian montmorillonite clay, was procured from “BENTAL” (Algerian Society of Bentonite). 2.2. Preparation of maghnite-H+ Maghnite-H+ was prepared according to the process reported in our previous study [19,20]. Raw-maghnite (20 g) was crushed for 20 min using a prolabo ceramic balls grinder. It was then dried for 2 h at 105 °C. The Maghnite was placed in an
Scheme 1.
3556
A. Harrane et al. / Materials Letters 61 (2007) 3555–3558
Fig. 1. IR spectrum of polyoxetane.
Erlenmeyer flask together with 500 ml of distilled water. The maghnite/water mixture was stirred using a magnetic stirrer and combined with 0.25 M sulphuric acid solution, until saturation was achieved over 2 days at room temperature, the mineral was then washed with distilled water to became sulphate free and then dried at 105 °C.
Fig. 3. 13C NMR spectrum of polyoxetane.
2.3. Kinetics procedure The ring opening bulk polymerization of oxetane was carried out in sealed tubes. Each tube contains a mixture of 1 g of oxetane and an amount of maghnite-H+. The mixtures were kept in thermostat at 0 °C and stirred with a magnetic stirrer under dry nitrogen. The reaction was terminated by distilled water. The resulting polymer was extracted with dichloromethane, precipitated into ice cold distilled water and was dried in a muffle at room temperature and under vacuum all night. The monomer conversion was determined gravimetrically by weighing the precipitated polymer.
Fig. 4. Effect of maghnite-H+ amount on the conversion of monomer (time: 30 min, T = 0 °C, monomer initial amount: 1 g).
2.4. Polymer characterization Measurements of 1H and 13C NMR spectra were conducted in CDCl3 solution under ambient temperature on an AM 300 FT
Fig. 2. 1H NMR spectrum of polyoxetane product of the reaction.
Bruker spectrometer using tetramethylsilane (TMS) as internal standard. IR absorption spectrum was recorded on an ATI Matson FTIR No 9501165 spectrometer using the KBr pressed disc technique.
Fig. 5. Effect of maghnite-H+ amount on Mn (time: 30 min, T = 0 °C, monomer initial amount: 1 g).
A. Harrane et al. / Materials Letters 61 (2007) 3555–3558 Table 1 Kinetic evolution of oxetane polymerization a initiated by maghnite-H + Time (min)
Conversion of monomer %w
Mn × 10− 3
Mw/Mn
10 15 20 25 30 35 40 45 50
3.54 9.67 42.65 63.23 58.12 65.15 76.11 87.54 87.86
0.37 0.82 2.42 5.22 4.45 5.23 4.37 2.92 2.46
2.12 2.11 2.24 2.14 2.17 2.45 3.01 3.34 3.12
Reaction temperature 0 °C. a Maghnite-H+/oxetane weight ratio = 10%.
3557
The present study is also concerned with polymerization and examines the catalytic activity of Algerian proton exchanged montmorillonite clay via oxetane cationic ring opening polymerization. The structure and the composition of the catalyst were reported in previous works [19,20]. In a previous work [24], it was demonstrated that there is an excellent correlation between the acid treatment and the catalytic activity of maghnite. It was reported that best values of monomer conversions were obtained with “maghnite-H+” which has been produced by treatment of raw-maghnite with 0.25 M sulphuric acid solution. This treatment leads to a complete saturation of montmorillonite with protons without destruction of the catalyst structure [28,29]. 3.1. Ring opening bulk polymerization of oxetane
Gel permeation chromatography (GPC) was performed with a Spectra-Physics chromatograph, equipped with four columns connected in series and packed with Ultrastyragel 103, 104, 105, 106 Å, tetrahydrofuran (THF) was used as solvent and the instrument was calibrated to a first approximation with polystyrene of known molecular weights. 3. Results and discussion The use of acid treated clays as a solid source of protons in many industrial significant reactions continues because they constitute a widely available, inexpensive solid source of protons, e.g. they were employed as cracking catalysts until the 1960s [25], and are still used actually in industrial processes such as the alkylation of phenols and the dimerization and polymerization of unsaturated hydrocarbons [26]. Montmorillonites have both Brønsted and Lewis acid sites and when exchanged with cations having a high charge density, as protons, produce highly active catalysts for acid-catalysed reactions [27]. Intercalated organic molecules are mobile and can be highly polarized when situated in the space between the charged clay layers. These exchanged montmorillonites have been successfully used as catalysts for the reactions of polymerization [19–21,25].
The cationic ring opening bulk polymerization of oxetane was examined in the presence of maghnite-H+ at 0 °C (Scheme 1). The IR measurements of the product are in a good agreement with the polyoxetane structure (Fig. 1). The characteristic vibration of C–O band is observed respectively at 1120 cm− 1. A weak absorbance around 3500 cm− 1 assigned to the hydroxyl group was observed. This indicated that polyoxetane possessed hydroxyl groups as the end groups, which seemed to be introduced by terminating and initiating processes. The following results may present the preliminary information on such mechanistic aspects of the polymerization. 1 H and 13C NMR measurements (Figs. 2 and 3) confirm the structure of polyoxetane that resulted from the reaction of polymerization. As shown in 1H NMR spectrum of the product, the signal assigned to the protons of methylene bonded to oxygen polyoxetane appeared at 3.49 ppm. The signal due to other methylene protons was observed at 1.84 ppm. 13C NMR analysis (Fig. 3) also clearly showed the resonances corresponding to polyoxetane carbons, δ 66.86 ppm (–OCH2–) and δ¨ 29.19 ppm (OCH2CH2–). 3.2. Effect of maghnite-H+/monomer weight ratio Figs. 4 and 5 show the effect of maghnite/monomer weight ratio on the conversion of oxetane and molecular weight of the polymer respectively. Indeed, using various amounts of maghnite-H+, 5, 10, 20,
Scheme 2.
3558
A. Harrane et al. / Materials Letters 61 (2007) 3555–3558
and 50% by weight, the polymerization of oxetane was carried in bulk at 0 °C for 30 min. It can be noted that increasing the weight ratio maghnite-H+/oxetane also increases the conversion of monomer to polymer and decreases the molecular weight of the resulting polymer. This result shows the effect of maghnite-H+ as a cationic catalyst. Similar results are obtained by Belbachir et al. [20,30] in the polymerization of isobutylene by maghnite-H+, which polymerizes only by the cationic process [31]. 3.3. Effect of time on the polymerization Polymerization using a weight ratio maghnite-H+/oxetane of 10% was carried out at 0 °C and the reaction was monitored at various times to study the evolution of monomer conversion and the molecular weight of the polymer with reaction time. The results are given in Table 1. The molecular weight increases with polymerization time and reaches a maximum after 35 min. The results show that after 40 min, the molecular weight decreases. This result suggests that chain transfer causes degradation and formation of cyclic oligomers and consequently may cause a decrease in the molecular weight. On the other hand, the monomer conversion increases with time and it can be noted that initially the polymerization proceeds very slowly; this can be considered as an induction period (15 min), which consumed approximately 10% of the monomer. At the end of this period, the polymerization process becomes faster. 3.4. Mechanism of the reaction According to the foregoing discussion and the results of product analysis, we may suggest a cationic mechanism for the resulting reaction of polymerization induced by “maghnite-H+” (Scheme 2). Protons carried by montmorillonite sheets of “maghnite-H+” induced the cationic polymerization, these montmorillonite sheets take place as counteranions. Propagation and termination then take place by conventional cationic ring opening mechanism. Termination was caused by H2O presented as adsorbed molecules in the maghnite-H+ surface.
4. Conclusions Maghnite-H+, a proton exchanged montmorillonite clay is an effective initiator for the ring opening polymerization of oxetane. In the polymerization, the solid catalyst was thought to act as an acid to generate cation species. Actually, the efficiency of the polymerization reflected the Lewis acidity of
maghnite-H+. Two main advantages were shown in the polymerization system using the solid acid maghnite-H+, that the catalyst could be removed from the mixture of the products by simple filtration and recycled without a loss of catalytic activity. References [1] J.V. Crivello, H. Sasaki, J. Macromol. Sci., Part A, Pure Appl. Chem. A30 (1983) 189. [2] H. Sasaki, J.M. Rudzinski, T. Kakuchi, J. Polym. Sci., A, Polym. Chem. 33 (1995) 1807. [3] T. Yashiro, T. Sathou, A. Kameyama, T. Nishikubo, J. Polym. Sci., A, Polym. Chem. 41 (2003) 2304. [4] M. Sangermano, R. Bongionavanni, G. Malucelli, A. Priola, J. Olbrych, A. Harden, N. Rehnberg, J. Polym. Sci., A, Polym. Chem. 42 (2004) 1415. [5] T. Saegusa, H. Fujii, S. Kobayashi, H. Ando, R. Hasegawa, Macromolecules 6 (1973) 26. [6] M. Bucquoye, E. Goethals, Makromol. Chem. 179 (1978) 1681. [7] S. Kanoh, T. Nishimura, T. Tsuchida, H. Senda, M. Motoi, M. Takani, N. Matsuura, Macromol. Chem. Phys. 203 (2002) 511. [8] S. Inoue, T. Aida, in: K.J. Ivin, T. Saegusa (Eds.), Ring Opening Polymerization, vol. 1, Elsevier, London, 1984, p. 185. [9] K. Arata, K. Tanabe, Catal. Rev., Sci. Eng. 25 (1983) 365. [10] G.W. Kabalka, R.M. Pagni, Tetrahedron 53 (1997) 7999. [11] G.H. Posner, M. Hulce, R.K. Rose, Synth. Commun. 11 (1981) 737. [12] E.R. Hitzky, B. Casal, J. Catal. 92 (1985) 291. [13] M. Onaka, M. Kawai, Y. Izumi, Chem. Lett. (1985) 779. [14] M. Onaka, A. Ohta, K. Sugita, Y. Izumi, Appl. Catal., A Gen. 125 (1995) 203. [15] S. Hayase, T. Ito, M. Wada, J. Polym. Sci., A, Polym. Chem. 19 (1981) 2541. [16] K. Kageyama, S. Ogino, T. Aida, Macromolecules 31 (1998) 4069. [17] K. Kageyama, T. Tatsumi, T. Aida, Polym. J. 31 (1999) 1005. [18] A.A. Vaidaya, V.G. Kumar, J. Appl. Polym. Sci. 70 (1998) 629. [19] M. Belbachir, A. Bensaoula. US Patent. No 6,274,527B1 (2001). [20] A. Harrane, R. Meghabar, M. Belbachir, Int. J. Mol. Sci. 3 (2002) 790. [21] R. Meghabar, A. Megherbi, M. Belbachir, Polymer 44 (2003) 2397. [22] A. Harrane, K. Oussadi, A. Belaouedj, R. Meghabar, M. Belbachir, J. Polym. Res. 12 (2005) 361. [23] A. Harrane, K. Oussadi, A. Belaouedj, R. Meghabar, M. Belbachir, J. Polym. Res. 12 (2005) 367. [24] A. Harrane, R. Meghabar, M. Belbachir, Des. Monomers Polym. 8 (2005) 11. [25] C.L. Thomas, J. Hickey, G. Stecker, Ind. Eng. Chem. 42 (1950) 866. [26] F. Hojabri, J. Appl. Chem. Biotechnol. 21 (1971) 87. [27] J.A. Ballantine, M. Davies, H. Purnell, J. C. S. Chem. Comm. 27 (1981) 428. [28] C. Breen, J. Madejovà, P. Komadel, J. Mater. Chem. 5 (1995) 496. [29] J. Madejovà, P. Komadel, J. Phys. Chem., B 10 (1997) 5324. [30] M. Belbachir, A. Bensaoula, US Patent 2003/0069446A1 (2003). [31] G. Odian, La Polymerisation: principes et Applications, Ed. Technica (NewYork, 1994) p 222.
Ring opening polymerization of oxetane by the use of a montmorillonite clay as catalyst Amine Harrane ⁎, Nacéra Naar, Mohammed Belbachir Laboratoire de Chimie des Polymères, Département de Chimie, Faculté des Sciences, Université d'Oran Es-Senia, BP No 1524 El M'Naouar, 31000 Oran, Algeria Received 21 June 2006; accepted 23 November 2006 Available online 15 December 2006
Abstract Maghnite-H+ was found to be an effective solid catalyst for the ring opening polymerization of oxetane. Maghnite-H+ is a proton exchanged montmorillonite clay. Effect of weight ratio of initiator/monomer and reaction time on the conversion of monomer and the molecular weight is investigated. Increasing maghnite-H+ proportion produced an increase in oxetane conversion and a decrease in Mn. A cationic mechanism for the reaction was proposed. © 2006 Elsevier B.V. All rights reserved. Keywords: Montmorillonite; Maghnite; Ring opening polymerization; Oxetane; Polyoxetane
1. Introduction Products obtained from oxetanes have attracted much attention, which can be used for adhesives instead of those from oxiranes [1–4]. The ring opening polymerization of oxetanes has been usually conducted by the use of cationic species [5–8], and the uses of various solid materials to induce oxetanes polymerization have been also well known [9,10]. In the solid catalysts, several derivatives based on silica such as aluminium minerals and zeolites are reported. Minerals and zeolites are reported to be effective for the ring opening reaction leading to 1,2-difunctionalized compounds from oxiranes [11–14]. Recently, in polymer synthesis, the silica derivatives have been employed for the well-defined ring opening polymerization of 1,2-epoxide and lactones [15–18]. The enhancement of such ring opening reaction is explained by, Brønsted and Lewis acidity with an appropriate reaction environment provided by the catalysts. In the present work, cationic ring opening polymerization of oxetane was induced by maghnite-H+ [19], an eco-catalyst proton exchanged montmorillonite clay. This new non-toxic cationic catalyst has exhibited higher efficiency via the polymerization of vinylic and heterocyclic monomers [20–24]. ⁎ Corresponding author. E-mail address: [email protected] (A. Harrane). 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.11.118
Techniques such as 1H NMR, 13C NMR, and IR, were used to characterize the products of the reaction. The effects of catalyst/ monomer weight ratio and time on monomer conversion and polymer average molecular weight were also examined. 2. Experimental 2.1. Materials Oxetane (Aldrich Chemical) was distilled under argon atmosphere before use. Dichloromethane was dried over CaH2 and distilled on the day of experiment. Raw-maghnite: Algerian montmorillonite clay, was procured from “BENTAL” (Algerian Society of Bentonite). 2.2. Preparation of maghnite-H+ Maghnite-H+ was prepared according to the process reported in our previous study [19,20]. Raw-maghnite (20 g) was crushed for 20 min using a prolabo ceramic balls grinder. It was then dried for 2 h at 105 °C. The Maghnite was placed in an
Scheme 1.
3556
A. Harrane et al. / Materials Letters 61 (2007) 3555–3558
Fig. 1. IR spectrum of polyoxetane.
Erlenmeyer flask together with 500 ml of distilled water. The maghnite/water mixture was stirred using a magnetic stirrer and combined with 0.25 M sulphuric acid solution, until saturation was achieved over 2 days at room temperature, the mineral was then washed with distilled water to became sulphate free and then dried at 105 °C.
Fig. 3. 13C NMR spectrum of polyoxetane.
2.3. Kinetics procedure The ring opening bulk polymerization of oxetane was carried out in sealed tubes. Each tube contains a mixture of 1 g of oxetane and an amount of maghnite-H+. The mixtures were kept in thermostat at 0 °C and stirred with a magnetic stirrer under dry nitrogen. The reaction was terminated by distilled water. The resulting polymer was extracted with dichloromethane, precipitated into ice cold distilled water and was dried in a muffle at room temperature and under vacuum all night. The monomer conversion was determined gravimetrically by weighing the precipitated polymer.
Fig. 4. Effect of maghnite-H+ amount on the conversion of monomer (time: 30 min, T = 0 °C, monomer initial amount: 1 g).
2.4. Polymer characterization Measurements of 1H and 13C NMR spectra were conducted in CDCl3 solution under ambient temperature on an AM 300 FT
Fig. 2. 1H NMR spectrum of polyoxetane product of the reaction.
Bruker spectrometer using tetramethylsilane (TMS) as internal standard. IR absorption spectrum was recorded on an ATI Matson FTIR No 9501165 spectrometer using the KBr pressed disc technique.
Fig. 5. Effect of maghnite-H+ amount on Mn (time: 30 min, T = 0 °C, monomer initial amount: 1 g).
A. Harrane et al. / Materials Letters 61 (2007) 3555–3558 Table 1 Kinetic evolution of oxetane polymerization a initiated by maghnite-H + Time (min)
Conversion of monomer %w
Mn × 10− 3
Mw/Mn
10 15 20 25 30 35 40 45 50
3.54 9.67 42.65 63.23 58.12 65.15 76.11 87.54 87.86
0.37 0.82 2.42 5.22 4.45 5.23 4.37 2.92 2.46
2.12 2.11 2.24 2.14 2.17 2.45 3.01 3.34 3.12
Reaction temperature 0 °C. a Maghnite-H+/oxetane weight ratio = 10%.
3557
The present study is also concerned with polymerization and examines the catalytic activity of Algerian proton exchanged montmorillonite clay via oxetane cationic ring opening polymerization. The structure and the composition of the catalyst were reported in previous works [19,20]. In a previous work [24], it was demonstrated that there is an excellent correlation between the acid treatment and the catalytic activity of maghnite. It was reported that best values of monomer conversions were obtained with “maghnite-H+” which has been produced by treatment of raw-maghnite with 0.25 M sulphuric acid solution. This treatment leads to a complete saturation of montmorillonite with protons without destruction of the catalyst structure [28,29]. 3.1. Ring opening bulk polymerization of oxetane
Gel permeation chromatography (GPC) was performed with a Spectra-Physics chromatograph, equipped with four columns connected in series and packed with Ultrastyragel 103, 104, 105, 106 Å, tetrahydrofuran (THF) was used as solvent and the instrument was calibrated to a first approximation with polystyrene of known molecular weights. 3. Results and discussion The use of acid treated clays as a solid source of protons in many industrial significant reactions continues because they constitute a widely available, inexpensive solid source of protons, e.g. they were employed as cracking catalysts until the 1960s [25], and are still used actually in industrial processes such as the alkylation of phenols and the dimerization and polymerization of unsaturated hydrocarbons [26]. Montmorillonites have both Brønsted and Lewis acid sites and when exchanged with cations having a high charge density, as protons, produce highly active catalysts for acid-catalysed reactions [27]. Intercalated organic molecules are mobile and can be highly polarized when situated in the space between the charged clay layers. These exchanged montmorillonites have been successfully used as catalysts for the reactions of polymerization [19–21,25].
The cationic ring opening bulk polymerization of oxetane was examined in the presence of maghnite-H+ at 0 °C (Scheme 1). The IR measurements of the product are in a good agreement with the polyoxetane structure (Fig. 1). The characteristic vibration of C–O band is observed respectively at 1120 cm− 1. A weak absorbance around 3500 cm− 1 assigned to the hydroxyl group was observed. This indicated that polyoxetane possessed hydroxyl groups as the end groups, which seemed to be introduced by terminating and initiating processes. The following results may present the preliminary information on such mechanistic aspects of the polymerization. 1 H and 13C NMR measurements (Figs. 2 and 3) confirm the structure of polyoxetane that resulted from the reaction of polymerization. As shown in 1H NMR spectrum of the product, the signal assigned to the protons of methylene bonded to oxygen polyoxetane appeared at 3.49 ppm. The signal due to other methylene protons was observed at 1.84 ppm. 13C NMR analysis (Fig. 3) also clearly showed the resonances corresponding to polyoxetane carbons, δ 66.86 ppm (–OCH2–) and δ¨ 29.19 ppm (OCH2CH2–). 3.2. Effect of maghnite-H+/monomer weight ratio Figs. 4 and 5 show the effect of maghnite/monomer weight ratio on the conversion of oxetane and molecular weight of the polymer respectively. Indeed, using various amounts of maghnite-H+, 5, 10, 20,
Scheme 2.
3558
A. Harrane et al. / Materials Letters 61 (2007) 3555–3558
and 50% by weight, the polymerization of oxetane was carried in bulk at 0 °C for 30 min. It can be noted that increasing the weight ratio maghnite-H+/oxetane also increases the conversion of monomer to polymer and decreases the molecular weight of the resulting polymer. This result shows the effect of maghnite-H+ as a cationic catalyst. Similar results are obtained by Belbachir et al. [20,30] in the polymerization of isobutylene by maghnite-H+, which polymerizes only by the cationic process [31]. 3.3. Effect of time on the polymerization Polymerization using a weight ratio maghnite-H+/oxetane of 10% was carried out at 0 °C and the reaction was monitored at various times to study the evolution of monomer conversion and the molecular weight of the polymer with reaction time. The results are given in Table 1. The molecular weight increases with polymerization time and reaches a maximum after 35 min. The results show that after 40 min, the molecular weight decreases. This result suggests that chain transfer causes degradation and formation of cyclic oligomers and consequently may cause a decrease in the molecular weight. On the other hand, the monomer conversion increases with time and it can be noted that initially the polymerization proceeds very slowly; this can be considered as an induction period (15 min), which consumed approximately 10% of the monomer. At the end of this period, the polymerization process becomes faster. 3.4. Mechanism of the reaction According to the foregoing discussion and the results of product analysis, we may suggest a cationic mechanism for the resulting reaction of polymerization induced by “maghnite-H+” (Scheme 2). Protons carried by montmorillonite sheets of “maghnite-H+” induced the cationic polymerization, these montmorillonite sheets take place as counteranions. Propagation and termination then take place by conventional cationic ring opening mechanism. Termination was caused by H2O presented as adsorbed molecules in the maghnite-H+ surface.
4. Conclusions Maghnite-H+, a proton exchanged montmorillonite clay is an effective initiator for the ring opening polymerization of oxetane. In the polymerization, the solid catalyst was thought to act as an acid to generate cation species. Actually, the efficiency of the polymerization reflected the Lewis acidity of
maghnite-H+. Two main advantages were shown in the polymerization system using the solid acid maghnite-H+, that the catalyst could be removed from the mixture of the products by simple filtration and recycled without a loss of catalytic activity. References [1] J.V. Crivello, H. Sasaki, J. Macromol. Sci., Part A, Pure Appl. Chem. A30 (1983) 189. [2] H. Sasaki, J.M. Rudzinski, T. Kakuchi, J. Polym. Sci., A, Polym. Chem. 33 (1995) 1807. [3] T. Yashiro, T. Sathou, A. Kameyama, T. Nishikubo, J. Polym. Sci., A, Polym. Chem. 41 (2003) 2304. [4] M. Sangermano, R. Bongionavanni, G. Malucelli, A. Priola, J. Olbrych, A. Harden, N. Rehnberg, J. Polym. Sci., A, Polym. Chem. 42 (2004) 1415. [5] T. Saegusa, H. Fujii, S. Kobayashi, H. Ando, R. Hasegawa, Macromolecules 6 (1973) 26. [6] M. Bucquoye, E. Goethals, Makromol. Chem. 179 (1978) 1681. [7] S. Kanoh, T. Nishimura, T. Tsuchida, H. Senda, M. Motoi, M. Takani, N. Matsuura, Macromol. Chem. Phys. 203 (2002) 511. [8] S. Inoue, T. Aida, in: K.J. Ivin, T. Saegusa (Eds.), Ring Opening Polymerization, vol. 1, Elsevier, London, 1984, p. 185. [9] K. Arata, K. Tanabe, Catal. Rev., Sci. Eng. 25 (1983) 365. [10] G.W. Kabalka, R.M. Pagni, Tetrahedron 53 (1997) 7999. [11] G.H. Posner, M. Hulce, R.K. Rose, Synth. Commun. 11 (1981) 737. [12] E.R. Hitzky, B. Casal, J. Catal. 92 (1985) 291. [13] M. Onaka, M. Kawai, Y. Izumi, Chem. Lett. (1985) 779. [14] M. Onaka, A. Ohta, K. Sugita, Y. Izumi, Appl. Catal., A Gen. 125 (1995) 203. [15] S. Hayase, T. Ito, M. Wada, J. Polym. Sci., A, Polym. Chem. 19 (1981) 2541. [16] K. Kageyama, S. Ogino, T. Aida, Macromolecules 31 (1998) 4069. [17] K. Kageyama, T. Tatsumi, T. Aida, Polym. J. 31 (1999) 1005. [18] A.A. Vaidaya, V.G. Kumar, J. Appl. Polym. Sci. 70 (1998) 629. [19] M. Belbachir, A. Bensaoula. US Patent. No 6,274,527B1 (2001). [20] A. Harrane, R. Meghabar, M. Belbachir, Int. J. Mol. Sci. 3 (2002) 790. [21] R. Meghabar, A. Megherbi, M. Belbachir, Polymer 44 (2003) 2397. [22] A. Harrane, K. Oussadi, A. Belaouedj, R. Meghabar, M. Belbachir, J. Polym. Res. 12 (2005) 361. [23] A. Harrane, K. Oussadi, A. Belaouedj, R. Meghabar, M. Belbachir, J. Polym. Res. 12 (2005) 367. [24] A. Harrane, R. Meghabar, M. Belbachir, Des. Monomers Polym. 8 (2005) 11. [25] C.L. Thomas, J. Hickey, G. Stecker, Ind. Eng. Chem. 42 (1950) 866. [26] F. Hojabri, J. Appl. Chem. Biotechnol. 21 (1971) 87. [27] J.A. Ballantine, M. Davies, H. Purnell, J. C. S. Chem. Comm. 27 (1981) 428. [28] C. Breen, J. Madejovà, P. Komadel, J. Mater. Chem. 5 (1995) 496. [29] J. Madejovà, P. Komadel, J. Phys. Chem., B 10 (1997) 5324. [30] M. Belbachir, A. Bensaoula, US Patent 2003/0069446A1 (2003). [31] G. Odian, La Polymerisation: principes et Applications, Ed. Technica (NewYork, 1994) p 222.