Synthesis of poly(3-caprolactone)-block -poly(n-butyl acrylate) by combining ring-opening polymerization and atom transfer radical polymerization with Ti[OCH 2 CCl 3 ] 4 as difunctional initiator: I. Kinetic study of Ti[OCH 2 CCl 3 ] 4 initiated ring-opening polymerization of 3-caprolactone Peichun Li a, c , Amar Zerroukhi b, * , Jianding Chen c , Yvan Chalamet a , Thomas Jeanmaire b , Zhean Xia c a Inge´nieriedesMate´riauxPolyme `res/LRMP, UMR CNRS 5223, Universite´ Jean Monnet, 23 rue du Dr Paul Michelon, 42023 Saint-Etienne, Cedex 2, France b Universite´ Jean Monnet, De´partement de Chimie, 23 rue du Dr Paul Michelon, 42023 Saint-Etienne, Cedex 2, France c School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, PR China article info Article history: Received 27 September 2008 Received in revised form 24 December 2008 Accepted 7 January 2009 Available online 14 January 2009 Keywords: 3-Caprolactone Ring-opening polymerization Atom transfer radical polymerization abstract A new titanium alkoxide, Ti[OCH 2 CCl 3 ] 4 , designed to combine the ring-opening polymerization (ROP) of 3-caprolactone and atom transfer radical polymerization (ATRP) of n-butyl acrylate, was synthesized through the ester-exchange reaction of titanium n-propoxide and 2,2,2-trichloroethanol. The mechanism and kinetics of Ti[OCH 2 CCl 3 ] 4 initiated bulk polymerization of 3-caprolactone were studied. The results demonstrate that the polymerization proceeds through the coordination–insertion mechanism and all the four alkoxide groups in Ti[OCH 2 CCl 3 ] 4 share a similar activity in the initiation. The determined polymerization activation energy is 70 kJ/mol. The polymerization process can be well predicted by the obtained kinetic parameters. Furthermore, PCL synthesized with Ti[OCH 2 CCl 3 ] 4 can be used as the macroinitiator in ATRP of n-butyl acrylate to synthesize poly(3-caprolactone)-block-poly(n-butyl acrylate) (PCL-b-PBA) copolymer. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction 3-Caprolactone is one of the most widely studied monomers for the synthesis of degradable materials, and the most practical and convenient strategy to synthesize poly(3-caprolactone) (PCL) is ROP initiated by metal alkoxides, such as aluminum [1–3], tin [4,5], magnesium [1,6], zinc [7,8], and titanium derivatives [1,9– 13]. By carefully selecting the initiator systems, PCL functionalized with different end groups have been obtained, such as halogen groups [14,15], double bond [16–18], hydroxyl groups [19,20], and silane [21–23], which provides a wide range of possibilities for the synthesis of PCL-based copolymers with advanced structures such as block [24–26], star-shaped [27,28], comblike [29], brushlike [30], or cross-linked networks [31,32]. Meanwhile, ATRP has been proved to be efficient to synthesize polymer with desired macromolecular architectures [33–36]. Therefore, it is very inter- esting to combine ROP and ATRP to synthesize PCL-based copolymers with controlled length, composition, and architecture of polymer chains [37–40]. This work is a part of the subject concerning the synthesis of PCL-b-PBA by controlled polymerization. In this study, we present the synthesis and characterization of a new titanium alkoxide containing halogen groups, Ti[OCH 2 CCl 3 ] 4 , which was designed to be efficient as the difunctional initiator to combine ROP of 3- caprolactone and ATRP of n-butyl acrylate. Then the mechanism and kinetics of Ti[OCH 2 CCl 3 ] 4 initiated ROP of 3-caprolactone were studied. The PCL synthesized with Ti[OCH 2 CCl 3 ] 4 was used as a macroinitiator in the ATRP of n-butyl acrylate to synthesize PCL- b-PBA copolymers. 2. Experimental 2.1. Materials Titanium n-propoxide (Aldrich, 98%), 2,2,2-trichloroethanol (Aldrich, 99%), N,N,N 0 ,N 00 ,N 00 -pentamethyldiethylenetriamine (PMDETA, Aldrich, 99%), and copper(I) chloride (Cu I Cl, Aldrich, 99%) were used as received. 3-Caprolactone (Solvay Company, 99%) and n-butyl acrylate (Aldrich, 98%) were distilled over calcium hydride. * Corresponding author. Tel.: þ33 477485100. E-mail address: amar.zerroukhi@univ-st-etienne.fr (A. Zerroukhi). Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer 0032-3861/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymer.2009.01.013 Polymer 50 (2009) 1109–1117