Research Article Received: 26 March 2013 Revised: 23 May 2013 Accepted article published: 25 June 2013 Published online in Wiley Online Library: (wileyonlinelibrary.com) DOI 10.1002/pi.4576 Bismuth complex catalysts for the in situ preparation of polycaprolactone/silicate bionanocomposites Hanane El Ghaoui, a Mustapha Raihane, a Benaissa Rhouta, b Natacha Bitinis, c Anna Carlmark, d Miguel Arroyo, c Raquel Verdejo, c Miguel A Lopez-Manchado c* and Mohammed Lahcini a* Abstract Solvent-free, bismuth-catalysed in situ polymerization of caprolactone in the presence of layered silicates enables the formulation of a series of polycaprolactone/silicate bionanocomposites. Three organophilic montmorillonites obtained by cationic exchange reaction with tetrabutylammonium iodide, benzyltriethylammonium chloride and vinylbenzyltriphenylphosphonium chloride salts, respectively, were used as reinforcing reagents for these materials. The effects of clay and bismuth catalyst type (bismuth(III) acetate and triphenylbismuth) are discussed on the basis of composite morphologies and molecular weights of resulting polymers. c  2013 Society of Chemical Industry Keywords: bionanocomposites; bismuth complex; in situ ring-opening polymerization; organoclay; poly(ǫ -caprolactone) INTRODUCTION Biodegradable polymers such as poly(ǫ -caprolactone) (PCL) and polylactide (PLA) are attracting considerable interest in materials science research since they have strong promise for the design of eco-friendly green nanocomposites for several applications, mainly for packaging and agricultural products. PCL is a synthetic biodegradable polymer whose physical properties and commercial availability make it a good substitute for conventional non- biodegradable polymers used not only for common applications but also for specific areas such as medicine 1 – 4 and agriculture. 5 – 8 However, applications of these biodegradable polymers are limited because of their deficiencies in mechanical and barrier properties. One option to overcome these limitations is to incorporate an environmentally friendly filler to improve the properties of such biodegradable polymers, particularly for use as packaging materials. In this framework, it has been demonstrated that the performances of biodegradable polymers can be greatly enhanced by the dispersion of nanometre-sized particles. 9 Among the most important types of nanofillers, those based on layered silicates have been most widely studied. 10 – 16 Montmorillonite (MMT) is the clay most commonly used in polymer nanocomposite preparation. 17 – 21 Due to their high specific surface and large aspect ratio, these fillers improve the behaviour of polymers at very low filler contents, provided that they exhibit good clay dispersion into the polymer matrix. In order to improve the dispersion of clay nanofillers in an organophilic matrix, large organic compounds are introduced into the clay galleries by cation exchange reaction with quaternary ammonium or phosphonium salts. 22 – 25 However, not only the pre-treatment of the filler but also an adequate compounding process are necessary to obtain intercalated and exfoliated polymer nanocomposites. Bionanocomposites based on PLA and clays have attracted great interest in today’s materials research, because these substances can significantly enhance the bionanocomposite properties especially when compared with neat PLA. These improvements can include high moduli, increased strength, flexibility and heat resistance, decreased gas permeability and flammability, increased rate of crystallization, and better control of degradability. 26 – 34 Bordes et al. 35 reported a review of an aspect of the state of the art in the wide field of bionanocomposite materials, namely bionanocomposites based on biopolyester/clay systems. Layered silicates are widely used in nanocomposite systems and biopolyesters are currently the most promising biopolymers for a wide range of important applications. ∗ Correspondence to: M.A. Lopez-Manchado, Instituto de Ciencia y Tecnolog´ ıa de Pol´ ımeros ICTP-CSIC, Juan de la Cierva, 3 28006-Madrid (Spain) E-mail: lmanchado@ictp.csic.es; and M. Lahcini, Laboratoire de Chimie Organom´ etallique et Macromoleculaire-Mat´ eriaux Composites (LCO2MC), Facult´ e des Sciences et Techniques Gu´ eliz,Universit´ e Cadi Ayyad, Av. Abdelkrim Khattabi, BP 549, Marrakech,Morocco, E-mail: lm.lahcini@uca.ma a Laboratoire de Chimie Organom´ etallique et Macromoleculaire-Mat´ eriaux Composites (LCO2MC), Facult´ e des Sciences et Techniques Gu´ eliz, Universit´ e Cadi Ayyad, Av. Abdelkrim Khattabi, BP 549, Marrakech, Morocco b Laboratoire de Mati` ere Condens´ ee et Nanostructures (LMCN), Facult´ e des Sciences et Techniques Gu´ eliz, Universit´ e Cadi Ayyad, Av. Abdelkrim Khattabi, BP 549, Marrakech, Morocco c Instituto de Ciencia y Tecnolog´ ı a de Pol´ ı meros, ICTP-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain d KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, Teknikringen 56, SE-100 44 Stockholm, Sweden Polym Int (2013) www.soci.org c  2013 Society of Chemical Industry