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International audience; In this work, we report the use of the diffusion-ordered spectroscopy (NMR DOSY) nuclear magnetic resonance (NMR) technique to follow the nitroxide-mediated polymerization (NMP) of methyl methacrylate (MMA), well known as a difficult monomer to polymerize by NMP. Two syntheses were carried out either in the presence or absence of a small amount of styrene at 80 °C, using N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl)nitroxide (SG1) as a control agent and 2-methylaminoxypropionic-SG1 alkoxyamine (BlocBuilder) as the initiator. Diffusion coefficients determined from NMR DOSY experiments could be accurately correlated to the weight average molar masses Mw of PMMA, and could thereby be used to confirm that the polymerization of pure MMA by NMP is uncontrolled due to disproportionation side reactions leading to non-reversible termination (i.e. dead chains). In a similar manner, the livingness of the PMMA chains grown in the presence of a small amount of styrene was confirmed by the linear evolution of the diffusion coefficient versus time (conversion) and the retention of the alkoxyamine chain end. Livingness was further assessed by NMR DOSY analysis of chain extensions with n-butyl acrylate. This all-in-one technique permits disproportionation side reactions, livingness, and evolution of the molar masses with time to be simultaneously followed.

cited By 0; International audience; The first nitroxide-mediated polymerization of butyl acrylate/methyl methacrylate and/or styrene diblock copolymers-based nanoclay composites is reported. Polybutyl acrylate (PBA) macroinitiators synthesized in the presence of raw and modified clays are used for chain extension. All materials are characterized by proton nuclear magnetic resonance, size exclusion chromatography, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry techniques. The obtained proton nuclear magnetic resonance and size exclusion chromatography results show that all syntheses are carried out in controlled manner. X-ray diffraction analysis of hybrid materials reveals the formation of different structures varying between exfoliated and disordered ones. These structures depend on nanoclay distribution in different (co)polymer matrix and probable polymer/nanoclay interactions. All PBA composites and hybrid diblock materials register the enhanced thermal stability and show two glass transition temperature Tg values corresponding to the two diblock acrylic macromolecular features. Montmorillonite diblock nanocomposites of poly(butyl acrylate-b-methyl methacrylate) and poly(butyl acrylate-b-styrene) copolymers are obtained from raw and polybutylacrylate PBA macroinitiator-modified clays by in situ nitroxide-mediated polymerization. All syntheses are carried out in a controlled manner, and hybrid materials reveal the formation of different structures, varying between exfoliated and disordered ones, relating to the enhancement of their thermal stability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this work, we describe the “in situ” synthesis of “all-acrylic” copolymer (n-butyl acrylate-co-methyl methacrylate)/clay materials at different low contents of raw and modified Montmorillonite (1–4 wt % versus monomer). The cationic 2,2′ azobis-(amidinopropane)dihydrochloride initiator was used to modified the clay by cation exchange in combination with the N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)] (SG1) nitroxide to synthesize the polymer/clay nanocomposite via nitroxide mediated controlled radical polymerization. All synthesized materials are characterized by proton nuclear magnetic resonance, size exclusion chromatography, thermogravimetric analysis and differential scanning calorimetry techniques. The thermo-mechanical properties of the synthesized materials are also reported. The results show that a decrease in molar masses and/or slight changes in molar compositions of poly (n-butyl acrylate- co-methyl methacrylate)/clay systems can be balanced by clay loading in polymer matrix, and consequently compensated or masked clay effects on physical properties of obtained materials. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

cited By 20; International audience; In this work, we report the synthesis of poly(n-butyl acrylate-co-methyl methacrylate) copolymers by the nitroxide mediated polymerization (NMP) technique, using N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl)nitroxide (SG1) as a control agent and 2-methylaminoxypropionic-SG1 alkoxyamine (BlocBuilder®) as the initiator. The copolymers are synthesized either by batch or semi-batch processes and the gradient profile is examined via the determination of the instantaneous fraction of monomer incorporated in the copolymer. A control of the molar mass together with low molar mass distribution (Mw/Mn < 1.4) is observed. The dependence of the copolymer glass transition temperature with conversion was followed by differential scanning calorimetry. The copolymers are investigated by carbon nuclear magnetic resonance and heteronuclear multiple bond correlation (HMBC) NMR sequences to study the effect of the monomer addition mode on the microstructure of copolymers. The thermomechanical properties of gradient copolymers are finally reported to establish the effect of the composition on the mechanical behaviour of the copolymers. © 2011 The Royal Society of Chemistry.