RAFT/MADIX Copolymerization of Vinyl Acetate and 5,6-Benzo-2-methylene-1,3-dioxepane Giovanna Gomez d’Ayala, 1 Mario Malinconico, 1 Paola Laurienzo, 1 Antoine Tardy, 2 Yohann Guillaneuf, 2 Muriel Lansalot, 3 Franck D’Agosto, 3 Bernadette Charleux 3 1 Istituto di Chimica e Tecnologia dei Polimeri, Via Campi Flegrei, 34 80078 Pozzuoli (NA), Italy 2 Aix-Marseille Universit e, CNRS, Institut de Chimie Radicalaire ICR UMR 7273, 13397 Marseille, France 3 Universit e de Lyon, Univ. Lyon 1, CPE Lyon, CNRS UMR 5265, Laboratoire de Chimie Catalyse Polyme ` res et Proc ed es (C2P2), Equipe LCPP Bat 308F, 43 Bd du 11 Novembre 1918, F-69616 Villeurbanne, France Correspondence to: G. Gomez d’Ayala (E - mail: giovanna.gomez@ictp.cnr.it); F. D’Agosto (E - mail: dagosto@lcpp.cpe.fr) Received 2 September 2013; accepted 4 October 2013; published online 29 October 2013 DOI: 10.1002/pola.26976 ABSTRACT: The synthesis of well-defined degradable poly(vinyl acetate) analogues is achieved by RAFT copolymerization of 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) and vinyl acetate (VAc) using methyl (ethoxycarbonothioyl)sulfanyl acetate (MEA) as controlling agent. Several monomer mixtures with low BMDO contents (<30 mol %) are employed to prepare dif- ferent copolymers. In all the cases, the evolution of molar masses and the dispersity values (<1.26) confirm the con- trolled feature of the polymerization. The livingness of the obtained chains is demonstrated by successful chain extension experiments with VAc, although the presence of dead chains is also shown. The introduction of ester groups into the main chain of these P(VAc-co-BMDO) copolymers allows their degra- dation when treated with a mixture of KOH/MeOH in reflux during 2.5 h. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 104–111 KEYWORDS: copolymerization; cyclic ketene acetal; degradable polymer; reversible addition fragmentation chain transfer; vinyl acetate INTRODUCTION The free radical polymerization of vinylic monomers leads to the formation of polymers with carbon– carbon link between the monomer units. In 1982, Bailey et al. 1 showed that ester links could also be incorporated into the polymer backbone by free radical ring opening poly- merization of specific monomers such as cyclic ketene ace- tals (CKAs). These monomers can indeed undergo radical addition on their C5C double bond that subsequently leads to propagation either by ring opening or ring retaining or by a combination of both depending especially on their struc- ture (Scheme 1). When the propagation step occurs only by successive radical ring opening reactions, the produced polymer is a polyester that can thus be obtained under much less demanding condi- tions than those required by the techniques usually employed to synthesize this type of polymers such as poly- condensation, ionic, and coordination ring opening polymer- izations. 2 Free radical copolymerization of cyclic ketene acetals with vinylic monomers has thus rapidly been fore- seen as a powerful tool to produce degradable polymers by taking advantage of the presence of ester groups along the backbone. A recent article by Agarwal 3 reviews the concepts and the progress in the field of free radical polymerization of cyclic ketene acetals for the synthesis of polyesters based materials. Among the different cyclic ketene acetal mono- mers, 5,6-benzo-2-methylene-1,3-dioxepane (BMDO, Scheme 2) has been shown to polymerize via free radical polymer- ization by successive ring opening reactions only. First homo- polymerized by Bailey et al., 1 BMDO has then been copolymerized with methyl methacrylate (MMA), 4,5 styrene (S), 6 N-isopropylacrylamide (NIPAM), 7,8 methacrylic acid (MAA), 9 n-butyl acrylate (BA), 10 poly(ethylene glycol) meth- acrylate (PEGMA) 11,12 to produce the corresponding degrad- able vinylic polymers. Since the advent of controlled/living free-radical polymeriza- tion (CRP) based on reversible deactivation of the propagat- ing radicals, 13 the design of complex macromolecules is much simpler and a myriad of macromolecular architectures has been made accessible under very simple synthetic condi- tions. Combining the best attributes of CRP with those of free radical ring opening polymerization should thus lead to degradable polymers with controlled and narrowly Additional Supporting Information may be found in the online version of this article. V C 2013 Wiley Periodicals, Inc. 104 JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2014, 52, 104–111 ARTICLE WWW.POLYMERCHEMISTRY.ORG JOURNAL OF POLYMER SCIENCE