Copolymerisation of e-caprolactone and trimethylene carbonate catalysed by methanesulfonic acid João M. Campos a , M. Rosário Ribeiro a,⇑ , M. Filipa Ribeiro a , Alain Deffieux b,c , Frédéric Peruch b,c,⇑ a Instituto de Biotecnologia e Bioengenharia, Departamento de Engenharia Química, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal b Univ. Bordeaux, LCPO, UMR 5629, F-33600 Pessac, France c CNRS, LCPO, UMR 5629, F-33600 Pessac, France article info Article history: Received 13 June 2013 Received in revised form 27 August 2013 Accepted 9 September 2013 Available online 25 September 2013 Keywords: Copolymerisation Ring-opening polymerisation Biomaterial Trimethylene carbonate e-Caprolactone abstract The copolymerisation of e-caprolactone (e-CL) and trimethylene carbonate (TMC) cata- lysed by methanesulfonic acid was investigated. Preliminary copolymerisation tests using a monofunctional initiator confirm that the side bidirectional propagation previously detected in the homopolymerisation of TMC is also present in the copolymerisation. The comonomers in the e-CL/TMC system do not follow first order kinetics. The values of the reactivity ratios obtained by the Kellen–Tüdös method (r e-CL = 2.90; r TMC = 0.62) suggest that random copolymerisation can be achieved, although the copolymer will be richer in e-CL. Dihydroxyl-telechelic e-CL/ TMC random copolymers were prepared using a bifunc- tional initiator. 1 H and 13 C NMR, SEC and DSC measurements show that the poly(TMC-co-e- CL) samples presented the expected microstructural characteristics, a unimodal molar- mass distribution and a very narrow polydispersity. Based on these features a novel route for the preparation of block copolyesters with tuned properties, and highly regarded in the development of materials for biomedicine, may be foreseen. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Synthetic aliphatic polyesters like poly(e-caprolactone), polylactide, polyglycolide (PCL, PLA, PGA) and related copolymers are highly regarded in the development of materials for biomedicine [1–3]. Aliphatic polycarbonates like poly(trimethylene carbonate) (PTMC), on the other hand, are not as attractive for biomedical applications, not only due to their weak mechanical properties, but also due to their higher stability in physiological conditions, strong hydrophobicity and lack of functionality, which re- duces their biological compatibility [4,5]. PTMC and related copolymers found their place in the field of biomaterials as components of block copolymers and in blends with brittle PLA, PCL or polyhydroxybutyrate (PHB) [5,6]. The copoly- merisation of trimethylene carbonate with cyclic esters of- fers a strategy to tune both the physicochemical properties and the degradation behaviour of the resulting materials. Cationic homo and copolymerisation of e-caprolactone and lactide monomers initiated by an alcohol and cata- lysed by trifluoromethanesulfonic acid (HOTf) or methane- sulfonic acid (MSA), proceed by an activated monomer (AM) mechanism in a controlled/living manner, without detectable side processes [7–14]. The use of these acid catalysts is very interesting from the viewpoint of operational simplicity and environmental compatibility, particularly for MSA. Nevertheless, perform- ing the controlled polymerisation of TMC using such cata- lysts is rather problematic. This occurs because, in addition to the main AM mechanism, where the monomer activated by the acid catalyst will undergo nucleophilic attack at the 0014-3057/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.eurpolymj.2013.09.008 ⇑ Corresponding authors. Tel.: +33 540 002 745 (F. Peruch), tel.: +351 21 8417325 (M. Rosário Ribeiro). E-mail addresses: rosario@ist.utl.pt (M.R. Ribeiro), peruch@enscbp.fr (F. Peruch). European Polymer Journal 49 (2013) 4025–4034 Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj