1 No Matter the Order of Monomer Addition For the Synthesis of Well-Defined Block Copolymers by Sequential Group Transfer Polymerization Using N-Heterocyclic Carbenes as Catalysts Jean Raynaud, a,b Na Liu, a,b Maréva Fèvre, a,b Yves Gnanou a,b and Daniel Taton* a,b a Centre National de la Recherche Scientifique, Laboratoire de Chimie des Polymères Organiques, 16 avenue Pey-Berland, F-33607 Pessac cedex, France; E-mail: taton@enscbp.fr b Université de Bordeaux, Laboratoire de Chimie des Polymères Organiques, IPB-ENSCBP, F-33607 Pessac cedex, France SUPPLEMENTARY INFORMATION Electronic Supplementary Material (ESI) for Polymer Chemistry This journal is © The Royal Society of Chemistry 2011