Efficiency Increase of Poly(ethylene terephthalate-co-isosorbide terephthalate) Synthesis using Bimetallic Catalytic Systems Jean Christophe Bersot, Nicolas Jacquel, Rene ´ Saint-Loup, Patrick Fuertes, Alain Rousseau, Jean Pierre Pascault, Roger Spitz, Franc ¸oise Fenouillot,* Vincent Monteil* Introduction In recent years, several biobased monomers have been studied, targeting the improvement of polycondensate properties or the replacement of petrochemical monomers. Due to their rigidity and their harmlessness, 1,4:3,6- dianhydrohexitols (DAHs) (isomannide, isosorbide, and isoidide) have been gaining more interest for their use as building blocks in polymer synthesis. [1–7] Of the three known isohexide isomers, only dianhydro-1,4:3,6-D-sorbi- tol (DAS) or isosorbide is currently produced on an industrial scale. Moreover, the recent increase of its production capacity with satisfactory purity levels leads isosorbide to be considered as one of the most-promising biobased comonomers for polycondensation reactions and, in particular, for the modification of aliphatic and aromatic polyesters. The addition of isosorbide has been studied for several large-scale aromatic polyesters such as poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT) [8,9] or poly(butylene terephthalate) (PBT), [10,11] and also in aliphatic polyesters. [12,13] In the case of PET, a small amount of isosorbide (2–6 mol% per total diol) can significantly increase the glass-transition temperature Full Paper J. C. Bersot, Dr. N. Jacquel, Dr. A. Rousseau, Prof. J. P. Pascault, Dr. F. Fenouillot Universite ´ de Lyon, F-69003 France, and Inge ´nierie des Mate ´riaux Polyme `res, INSA-Lyon, IMP UMR5223, F-69621 Villeurbanne, France E-mail: francoise.fenouillot@insa-lyon.fr Dr. R. Saint-Loup, Dr. P. Fuertes Roquette Fre `res, Division Recherche, F-62080 Lestrem, France Dr. R. Spitz, Dr. V. Monteil Universite ´ de Lyon, F-69003, France, and Laboratoire de Chimie Catalyse Polyme `res et Proce ´de ´s (C2P2), LCPP team Bat 308F, CPE Lyon, CNRS UMR 5265, 43 Blvd. du 11 Novembre 1918, F-69616 Villeurbanne, France E-mail: monteil@lcpp.cpe.fr New catalytic systems are developed to increase the transesterification efficiency during the synthesis of poly(ethylene terephthalate-co-isosorbide terephthalate) with the aim of compen- sating for the lack of reactivity of the isosorbide and to reduce the coloration of the polymer. The combination of antimony oxide with a second metal (lithium-, magnesium-, or aluminium-based compounds) is investigated, leading to the discov- ery of innovative antimony-based bimetallic cat- alytic systems that exhibit a higher polymerization efficiency, even at high isosorbide contents (20%) and, in some cases, lower coloration. 2114 Macromol. Chem. Phys. 2011, 212, 2114–2120 ß 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com DOI: 10.1002/macp.201100146