Direct Synthesis of Vinylidene Fluoride-Based Amphiphilic Diblock Copolymers by RAFT/MADIX Polymerization Etienne Girard, †,‡ Jean-Daniel Marty, ‡ Bruno Ameduri,* ,§ and Mathias Destarac* ,† † LHFA, UMR 5069, Universite ́ de Toulouse, 118, route de Narbonne F-31062 Toulouse, Cedex 9, France ‡ IMRCP, UMR 5623, Universite ́ de Toulouse, 118, route de Narbonne F-31062 Toulouse, Cedex 9, France § Institut Charles Gerhardt, Ingé nierie et Architectures Macromole ́ culaires, UMR 5253, Ecole Nationale Supe ́ rieure de Chimie de Montpellier, 8, rue de l’Ecole Normale F-34296 Montpellier, France * S Supporting Information ABSTRACT: We herein report the synthesis of original vinylidene fluoride (VDF)-based amphiphilic block copolymers by RAFT/MADIX polymerization. The controlled polymer- ization of VDF could be successfully mediated by a xanthate chain transfer agent as evidenced by size exclusion chromatog- raphy (SEC), 19 F NMR, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Copolymers of VDF and perfluoro(methyl vinyl ether) (PMVE) of varying controlled chain lengths were also obtained. Finally, the direct synthesis of main-chain fluorinated amphiphilic block copolymers was performed from hydrophilic poly(N, N-dimethylacrylamide) macro-RAFT agents. It is expected that this finding will open interesting perspectives for the development of new class of polymeric surfactants for the stabilization of emulsions based on water and supercritical carbon dioxide media. F luoropolymers possess unique properties of resistance to thermal aging or weather aggressions and excellent inertness to a wide range of chemical environments. 1 However, their low solubility in most organic solvents except chloro- fluorocarbons represents a major concern for the industrial scale production of these materials in homogeneous processes. To circumvent the use of such environmentally harsh solvents, DeSimone and co-workers first reported the solution radical polymerization of fluoroacrylate monomers in supercritical carbon dioxide (sc-CO 2 ). 2 Indeed, polyfluoroacrylates feature quadrupolar interactions with CO 2 and low self-interactions, which made them readily soluble in sc-CO 2 even at high molecular weight and under low pressure conditions (ca. 170 bar). 3 In contrast, poly(vinylidene fluoride) (PVDF), a specialty fluoropolymer with widespread use in industry, 4 exhibits lower solubility in sc-CO 2 , 5 because of its semicrystal- line character. Actually, only VDF oligomers possess high partition coefficients in sc-CO 2 at 150 bar and 338 K. 6,7 Consequently, high molecular weight PVDF can only be synthesized by dispersion 8 or precipitation 9,10 polymerization in sc-CO 2 . This heterogeneous process can be also switched to a solution polymerization under extremely high pressures (ca. 1500 bar) 11 or via a copolymerization of vinylidene fluoride (VDF) with vinyl acetate 12 or hexafluoropropylene 13 under milder pressure conditions. Hence, polyfluoroacrylates and low molecular weight polyfluoroolefins are natural candidates as CO 2 -philic building blocks for the design of CO 2 -philic block copolymers. 14,15 To this end, macromolecular engineering by reversible-deactivation radical polymerization (RDRP) 16,17 technologies is a resource- ful toolbox for the synthesis of amphiphilic copolymers. Thus, original well-defined amphiphilic block copolymers were synthesized with fluorinated styrenic and methacrylate monomers 18 whose polymerization could be easily imple- mented and controlled by RDRP techniques. In contrast, examples of fluorinated amphiphilic copolymers that incorpo- rate polyfluoroolefin blocks are scarce in the literature. In fact, RDRP techniques with the exceptions of (reverse) iodine transfer polymerization ((R)ITP) 19-22 and some alkylborane/ oxygen couples 23 have so far failed to control the radical polymerization of fluoroolefins and VDF in particular. First examples came from derivative strategies using VDF telomers 24,25 or VDF/8-bromo-1H,1H,2H-perfluorooct-1-ene copolymers 26 as atom transfer radical polymerization macro- initiators for the formation of block and graft copolymers, respectively. For its part, ITP allowed the direct synthesis of PVDF-polystyrene block copolymers from iodoperfluoralkane chain transfer agents. 27 However, (R)ITP polymerization has been only successfully applied to hydrophobic monomers including styrenics, (meth)acrylates, and to a lesser extent, vinyl acetate (VAc). 28 Received: October 10, 2011 Accepted: January 1, 2012 Published: January 12, 2012 Letter pubs.acs.org/macroletters © 2012 American Chemical Society 270 dx.doi.org/10.1021/mz2001143 | ACS Macro Lett. 2012, 1, 270-274