Synthèse d'agents RAFT macromoléculaires hydrophiles à base d'acide (méth)acrylique ou d'alginate pour l'élaboration de nanoparticules par polymérisation en émulsion

This work describes the synthesis of nanoparticles stabilized by polyelectrolytes from synthetic(poly((meth)acrylic acid)) or natural (alginate) source by controlled free radical polymerization (CRP),namely RAFT, in emulsion. This process is based on the use of a hydrophilic polymer prepared by RAFT (i.e. macroRAFT) which is reactivated in water for the polymerization of a hydrophobic monomer. The formation of amphiphilic block copolymers which self-assemble in situ leads to the formation of nanoparticles. Firstly, we tried to perform the whole process in water. The RAFT polymerization of acrylic acid and methacrylic acid was studied in this context. Well-defined homopolymers were obtained under a large range of conditions, and further used as macroRAFTs in emulsion polymerization of hydrophobic monomers. Stable nanoparticles composed of well-defined amphiphilic block copolymers were produced. It was shown that the control of the polymerization and the nucleation were strongly dependent on the pH. Nevertheless, a good colloidal stability wasobserved in all cases. This “one-pot” process was then extrapolated to the synthesis of particles stabilized by hydrophilic copolymers of N-acryloylmorpholine (NAM) and alginate macromonomer. Nano-objects with various morphologies were obtained. In order to better understand the formation of these morphologies, a model system using a hydrophilic copolymer of NAM and a polyNAM macromonomer obtained by RAFT polymerization was studied in styrene emulsion polymerization.Ces travaux décrivent la synthèse de nanoparticules stabilisées par des polyélectrolytes d’originesynthétique (poly(acide (méth)acrylique)) ou naturelle (alginate) par polymérisation radicalairecontrôlée (PRC) de type RAFT en émulsion. Ce procédé est basé sur l’utilisation d’un polymèrehydrophile obtenu par RAFT (macroRAFT) qui est réactivé dans l’eau pour la polymérisation d’unmonomère hydrophobe. Des copolymères à blocs amphiphiles sont ainsi générés et s’auto-assemblent in situ pour former des nanoparticules. Dans un premier temps, nous avons cherché à conduire l’ensemble du procédé en milieu aqueux. Des études ont ainsi été menées sur la polymérisation RAFTdans l’eau de l’acide acrylique et de l’acide méthacrylique. Des homopolymères bien définis ont été obtenus sur une large gamme de conditions, puis ont été utilisés comme macroRAFTs pour la polymérisation en émulsion de monomères hydrophobes. Des nanoparticules stables constituées de copolymères à blocs amphiphiles bien définis ont été produites. Il a été montré que le contrôle de la polymérisation et la nucléation dépendaient fortement du pH, mais qu’une bonne stabilité colloïdale était néanmoins observée dans tous les cas. Ce procédé "one-pot " a ensuite été extrapolé à la synthèse de particules stabilisées par des copolymères hydrophiles de N-acryloylmorpholine (NAM) et de macromonomères d’alginate. Des nano-objets aux morphologies variées ont été obtenus. Afin de mieux appréhender la formation de ces morphologies, un système modèle employant un copolymère hydrophile de NAM et de macromonomère de polyNAM obtenu par polymérisation RAFT a été étudiépour la polymérisation en émulsion du styrène

Synthesis of poly(meth)acrylic acid and alginate-based hydrophilic macromolecular RAFT agents for the design of nanoparticles by emulsion polymerization

Ces travaux décrivent la synthèse de nanoparticules stabilisées par des polyélectrolytes d’originesynthétique (poly(acide (méth)acrylique)) ou naturelle (alginate) par polymérisation radicalairecontrôlée (PRC) de type RAFT en émulsion. Ce procédé est basé sur l’utilisation d’un polymèrehydrophile obtenu par RAFT (macroRAFT) qui est réactivé dans l’eau pour la polymérisation d’unmonomère hydrophobe. Des copolymères à blocs amphiphiles sont ainsi générés et s’auto-assemblent in situ pour former des nanoparticules. Dans un premier temps, nous avons cherché à conduire l’ensemble du procédé en milieu aqueux. Des études ont ainsi été menées sur la polymérisation RAFTdans l’eau de l’acide acrylique et de l’acide méthacrylique. Des homopolymères bien définis ont été obtenus sur une large gamme de conditions, puis ont été utilisés comme macroRAFTs pour la polymérisation en émulsion de monomères hydrophobes. Des nanoparticules stables constituées de copolymères à blocs amphiphiles bien définis ont été produites. Il a été montré que le contrôle de la polymérisation et la nucléation dépendaient fortement du pH, mais qu’une bonne stabilité colloïdale était néanmoins observée dans tous les cas. Ce procédé "one-pot " a ensuite été extrapolé à la synthèse de particules stabilisées par des copolymères hydrophiles de N-acryloylmorpholine (NAM) et de macromonomères d’alginate. Des nano-objets aux morphologies variées ont été obtenus. Afin de mieux appréhender la formation de ces morphologies, un système modèle employant un copolymère hydrophile de NAM et de macromonomère de polyNAM obtenu par polymérisation RAFT a été étudiépour la polymérisation en émulsion du styrène.This work describes the synthesis of nanoparticles stabilized by polyelectrolytes from synthetic(poly((meth)acrylic acid)) or natural (alginate) source by controlled free radical polymerization (CRP),namely RAFT, in emulsion. This process is based on the use of a hydrophilic polymer prepared by RAFT (i.e. macroRAFT) which is reactivated in water for the polymerization of a hydrophobic monomer. The formation of amphiphilic block copolymers which self-assemble in situ leads to the formation of nanoparticles. Firstly, we tried to perform the whole process in water. The RAFT polymerization of acrylic acid and methacrylic acid was studied in this context. Well-defined homopolymers were obtained under a large range of conditions, and further used as macroRAFTs in emulsion polymerization of hydrophobic monomers. Stable nanoparticles composed of well-defined amphiphilic block copolymers were produced. It was shown that the control of the polymerization and the nucleation were strongly dependent on the pH. Nevertheless, a good colloidal stability wasobserved in all cases. This “one-pot” process was then extrapolated to the synthesis of particles stabilized by hydrophilic copolymers of N-acryloylmorpholine (NAM) and alginate macromonomer. Nano-objects with various morphologies were obtained. In order to better understand the formation of these morphologies, a model system using a hydrophilic copolymer of NAM and a polyNAM macromonomer obtained by RAFT polymerization was studied in styrene emulsion polymerization

RAFT Polymerization of Methacrylic Acid in Water

International audienc

The Effect of Hydrophile Topology in RAFT-Mediated Polymerization-Induced Self-Assembly.

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Amphiphilic block copolymers from a direct and one pot RAFT synthesis in water

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From well-defined poly(N-acryloylmorpholine)-stabilized nanospheres to uniform mannuronan- and guluronan-decorated nanoparticles by RAFT polymerization-induced self-assembly

International audienceNon-ionic poly(N-acryloylmorpholine) (PNAM)-decorated polystyrene (PS) particles were synthesized by polymerization-induced self-assembly (PISA) in emulsion, mediated by the reversible additionfragmentation chain transfer (RAFT) technique, in a one-pot/two-step process. PNAM was first prepared by RAFT polymerization in water using 4-cyano-4-thiothiopropylsulfanyl pentanoic acid (CTPPA) as chain transfer agent. Chain extension of PNAM by a PS block was then accomplished by the polymerization of styrene in water. Spherical nanoparticles (number-average diameter < 60 nm) exclusively composed of well-defined PNAM-b-PS amphiphilic block copolymers (1.1 < D < 1.4) were successfully obtained under a broad range of conditions (PNAM number-average molar mass of 2000, 4000 and 8000 g mol(-1), and average polymerization degree of the PS block from 150 up to 1600). Mannuronan (ManA(17))-and guluronan (GulA(20))-decorated nanoparticles were further synthesized according to a similar PISA process. Glycuronan macromonomers carrying a methacrylate polymerizable group (ManA(17)MA or GulA(20)MA) were first copolymerized with N-acryloylmorpholine (NAM) under successful RAFT control using CTPPA. The resulting hydrophilic P(NAM-co-ManA(17)MA) and P(NAM-co-GulA(20)MA) macroRAFT agents were then used to polymerize styrene in water. Spherical glycuronan-decorated nanoparticles composed exclusively of amphiphilic block copolymers were successfully obtained for both glycuronan-based macroRAFT agents. (C) 2016 Elsevier Ltd. All rights reserved

Batch emulsion polymerization mediated by poly(methacrylic acid) macroRAFT agents: one-pot synthesis of self-stabilized particles

International audienceThe present paper describes the successful one-pot synthesis of self-stabilized particles composed of amphiphilic block copolymers based on poly(methacrylic acid) (PMAA) obtained by polymerization-induced self-assembly. First, controlled radical polymerization of MAA is performed in water using the RAFT process by taking advantage of our recent results showing the successful RAFT polymerization of MAA in water [Chaduc Macromolecules 2012, 45, 1241−1247]. The so-formed hydrophilic macroRAFT agents are then chain-extended in situ with a hydrophobic monomer to form amphiphilic block copolymer chains of controlled molar mass that self-assemble into stable nanoparticles. Various parameters such as the pH, the molar mass and the concentration of the PMAA segments or the nature of the hydrophobic block have been investigated

Effect of the pH on the RAFT Polymerization of Acrylic Acid in Water. Application to the Synthesis of Poly(acrylic acid)-Stabilized Polystyrene Particles by RAFT Emulsion Polymerization

International audienceThe reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylic acid (AA) in water was studied in detail at different pHs using 4-cyano-4-thiothiopropylsulfanyl pentanoic add (CTPPA) as a control agent and 4,4'-azobis(4-cyanopentanoic acid) (ACPA) as an initiator. Well-defined hydrophilic macromolecular RAFT agents (PAA-CTPPA) were obtained and further used directly in water for the polymerization of styrene. The corresponding polymerization-induced self-assembly (PISA) process was evaluated at different pHs and it was shown that working in acidic conditions (pH = 2.5) led to well-defined amphiphilic block copolymer particles (D < 1.4) of small size (below 50 nm). When the pH increased, the control over the growth of the polystyrene (PS) block was gradually lost. Chain extension experiments of PAA-CTPPA with N-acryloylmorpholine (NAM), a hydrosoluble and non-pH sensitive monomer, performed at different pHs showed that the very first addition-fragmentation steps that occurred in water were impeded when PAA was ionized leading to partial consumption of PAA-CTPPA and thus to PS molar masses higher than expected. Varying the PAA-CTPPA concentration at pH = 2.5 led in all cases to stable particles composed of well-defined block copolymers with PS segments of different molar masses

Synthesis of HCN-like poly(methyl methacrylate)/polystyrene/silica colloidal molecules

This communication reports about the feasibility of preparing triphasic clusters made of the combination of silica, polystyrene and poly(methyl methacrylate) nanoparticles. Silica-polystyrene dimers were used as seeds in methyl methacrylate emulsion polymerisation. The competition between silica surface nucleation and swelling/phase separation phenomena from the polystyrene nodule is discussed

RAFT Polymerization of Methacrylic Acid in Water

Reversible addition–fragmentation chain transfer (RAFT) polymerization of methacrylic acid was successfully performed in water in the presence of a trithiocarbonate, the 4-cyano-4-thiothiopropylsulfanylpentanoic acid (CTPPA), as a RAFT agent. Several parameters such as the temperature, the concentration, the pH, the targeted polymerization degree, and the initiator concentration were studied. For pH value below the p<i>K</i>_a of MAA, well-defined PMAA chains with different molar mass up to 92 000 g mol^–1 exhibiting low dispersity (<i>Đ</i> < 1.19) were obtained under a broad range of synthetic conditions