Elodie Bourgeat-Lami - Academia.edu (original) (raw)

Papers by Elodie Bourgeat-Lami

Macromolecules, Jan 25, 2005

Polystyrene (PS)-grafted silica nanoparticles were prepared by nitroxide-mediated polymerization ... more Polystyrene (PS)-grafted silica nanoparticles were prepared by nitroxide-mediated polymerization of styrene using N-tert-butyl-N-[1-diethylphosphono(2,2-dimethylpropyl)] nitroxide (DEPN) as mediator. Two routes were investigated to graft the alkoxyamine initiator onto silica. In the first route, (acryloxypropyl)trimethoxysilane (APTMS) was covalently attached to silica and the alkoxylamine was formed in situ by spin trapping the acryloxy radicals produced by reaction of azobisisobutyronitrile (AIBN) with the grafted APTMS molecules using DEPN as radical trap. In the second route, the surface alkoxyamine initiator was produced in a one-step process by reacting simultaneously DEPN, AIBN, and APTMS in the presence of silica. Next, polystyrene chains with controlled molecular weights and narrow polydispersities were grown from the alkoxyamine-functionalized nanoparticle surface. The amount of polystyrene grafted to the surface was determined by thermogravimetric analysis, and was found to increase with increasing grafting density of the alkoxyamine initiator. The resulting PS-grafted silica particles exhibited better colloidal stability and enhanced dispersability in toluene, a good solvent for polystyrene.

Applied Clay Science, 2016

Polymer Bulletin, Dec 1, 1995

ABSTRACT

HAL (Le Centre pour la Communication Scientifique Directe), 2010

Applied Surface Science, 2017

$Research paper thumbnail of Chapter 13 Polymer\textendashClay Nanocomposite Particles and Soap-free Latexes Stabilized by Clay Platelets: State of the Art and Recent Advances$

HAL (Le Centre pour la Communication Scientifique Directe), Sep 1, 2010

HAL (Le Centre pour la Communication Scientifique Directe), Dec 9, 2019

In this chapter, recent advances in the synthesis of waterborne LDH/polymer nanocomposites by usi... more In this chapter, recent advances in the synthesis of waterborne LDH/polymer nanocomposites by using LDH and/or latexes as building blocks of self-assembled materials are reviewed. Three main routes can be distinguished: electrostatic assembly of preformed LDH particles with oppositely charged latex particles, in-situ polymerization involving the formation of polymer latexes in the presence of LDH particles, and latex-templating which consists in LDH synthesis at the latex surface or confined in a polymeric colloid crystal used in this case as sacrificial template. The mechanical and flame retardancy properties of the resulting LDH nanocomposites are reviewed, providing insight into the main requirements of LDH fillers with respect to various applications. The performance of LDH macroporous structures as a function of their porosity is also discussed.

Journal of Colloid and Interface Science, Jun 1, 2002

Following a previous work (J. L. Luna-Xavier et al., Colloid Polym. Sci.279, 947 (2001)), silica-... more Following a previous work (J. L. Luna-Xavier et al., Colloid Polym. Sci.279, 947 (2001)), silica-poly (methyl methacrylate) (PMMA) nanocomposite latex particles have been synthesized in emulsion polymerization using a cationic initiator, 2,2&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-azobis (isobutyramidine) dihydrochloride (AIBA), and a nonionic polyoxyethylenic surfactant (NP30). Silica beads with diameters of 68, 230, and 340 nm, respectively, were used as the seed. Coating of the silica particles with PMMA was taking place in situ during polymerization, resulting in the formation of colloidal nanocomposites with a raspberry-like or a core-shell morphology, depending on the size and nature of the silica beads. The amount of surface polymer was quantified by means of ultracentrifugation and thermogravimetric analysis as extensively described in the first article of the series (see above reference). The influence of some determinant parameters such as the pH of the suspension, the initiator, silica, monomer, or surfactant concentration on the amount of coating polymer and on the efficiency of the coating reaction was investigated in details and discussed in light of the physicochemical properties of the seed mineral. Electrostatic attraction between the positive end groups of the macromolecules and the inorganic surface proved to be the driving force of the polymer assembly on the seed surface at high pH, while polymerization in adsorbed surfactant bilayers (so-called admicellar polymerization) appeared to be the predominant mechanism of coating at lower pH. Optimal conditions have been found to reach high encapsulation efficiencies and to obtain a regular polymer layer around silica.

Journal of Colloid and Interface Science, Feb 1, 1999

rounded by a polymer shell (1-3). The technique of poly-Polymer encapsulation of small silica par... more rounded by a polymer shell (1-3). The technique of poly-Polymer encapsulation of small silica particles, using dispermer encapsulation is becoming more and more popular since sion polymerization of styrene in aqueous ethanol medium with polymer-encapsulated particles offer very interesting actual poly(N-vinyl pyrrolidone) (PVP) as stabilizer, is described. Siland potential applications. Encapsulated pigments are inica particles, directly synthesized by the Stö ber process in an volved in the manufacture of cosmetics, inks, and paints to aqueous ethanol medium, are either unreacted (hydrophilic improve the compatibility between the filler and the binder. character) or coated with 3-(trimethoxysilyl) propyl methacry-The process of encapsulation is of particular interest in agrilate (MPS) (hydrophobic character) , which is grafted at the culture and pharmaceutical industries to produce controlledsilica particle surface. When the bare silica particles are used release products such as encapsulated pesticides and drugs as the seed, there is a strong tendency of the silica beads to cover the surface of the polystyrene particles and obviously en-(4). Encapsulation technologies have developed to reduce capsulation does not occur. On the contrary, when the silica toxicity, to mask taste and odor, to facilitate storage or transsurface is made hydrophobic by coating, the inorganic particles port, and to improve the stability of the encapsulated product. are entirely contained in the polystyrene particles as evidenced Polymer-encapsulated inorganic particles may also have inby microscopy techniques (TEM, SEM, AFM). It is shown that teresting properties in areas such as adhesives, textiles, opsome polystyrene chains are then chemically bonded to the silica tics, and electronics (5). particles, through the coupling agent MPS, and that only a small Most methods of encapsulation employ, so far, mechaniamount of bonded polystyrene, compared to the total polystycal processes. Recently, a new encapsulation technology has rene synthesized, is sufficient to obtain encapsulation of the been developed which consists in the coating of fine inorsilica particles with the entire amount of polystyrene syntheganic powders (submicrometer in size) in aqueous system sized during the polymerization. Under our experimental condiby emulsion polymerization. This new polymer-encapsulations, each polystyrene latex particle contains, on average, 4 to 23 silica beads depending, in particular, on the size of the silica. tion process is of particular interest in the paint industry We believe that it is possible to control the composite particle where a uniform distribution of the pigment in the matrix size and morphology by a convenient choice of the composition is required. Latex-encapsulated pigments offer many advanof the system. Moreover, this new polymer-encapsulation protages. The encapsulation of titanium dioxyde with poly cess could be used to synthesize other organic-inorganic com-(methyl methacrylate) has been extensively studied by Caris posite particles, using, for example, other monomers or mineret al. (6-9), who used titanate coupling agents to improve als.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 22, 2013

Elsevier eBooks, 2020

Abstract In this chapter, recent advances in the synthesis of layered double hydroxide (LDH) wate... more Abstract In this chapter, recent advances in the synthesis of layered double hydroxide (LDH) waterborne polymer nanocomposites by using LDH and/or latexes as building blocks of self-assembled materials are reviewed. Three main routes can be distinguished: electrostatic assembly of preformed LDH particles with oppositely charged latex particles, in situ polymerization involving the formation of polymer latexes in the presence of LDH particles, and latex-templating, which consists of LDH synthesis at the latex surface or confined in a polymeric colloid crystal used in this case as a sacrificial template. Finally, the mechanical and flame-retardancy properties of the resulting LDH nanocomposites are reviewed, providing insight into the main requirements of LDH fillers with respect to various applications. The performance of LDH macroporous structures as a function of their porosity is also discussed.

HAL (Le Centre pour la Communication Scientifique Directe), Jun 21, 2003

International audienc

Macromolecular Reaction Engineering, Jul 28, 2022

Investigation of particle nucleation in surfactant-free emulsion polymerization of styrene using ... more Investigation of particle nucleation in surfactant-free emulsion polymerization of styrene using Laponite clay as Pickering stabilizer is considered. The effective number of clay platelets contributing to the surface charge of the polymer particles was calculated, and used to estimate their stabilizing efficiency. A coagulative nucleation mechanism was proposed and the coagulation coefficient was calculated using the DLVO theory. The Hamaker constant involved in the attractive potential of the clay-polymer composite particles was measured experimentally. The model was found to fit the experimental data in terms of the number of nucleated particles and the nucleation period. The effective number of clay platelets contributing to the surface charge was found higher than the number of platelets allowing full polymer latex surface coverage at the end of nucleation. Moreover, efficient stabilization against coagulation required almost complete coverage.

ACS Macro Letters, Nov 3, 2022

Owing to the benefits of using natural or artificial light sources as a stimulus, photo-induced r... more Owing to the benefits of using natural or artificial light sources as a stimulus, photo-induced reversible-deactivation radical polymerization (photoRDRP) techniques have been recognized to be a powerful "green" platform for the preparation of well-defined polymers. However, the development of highly efficient visible light-induced photoRDRP processes in aqueous dispersed media remains a challenge due to light scattering and refraction by monomer droplets or colloidal particles. In this work, an efficient green photocatalyst, carbon quantum dots (CQDs), was introduced to visible light-mediated miniemulsion atom transfer radical polymerization (ATRP), leading to highly efficient polymerizations with reaction rates (>80% monomer conversion within 1h) much higher than in previous studies. This heterogeneous photocatalytic system is presumed to involve three catalytic cycles in: i) the aqueous phase, ii) the oil-water interface and iii) the monomer droplets. The effect of different polymerization parameters on the polymerization reaction was investigated, including the amounts of surfactant and CQDs, CuBr 2 dosage and solid content. Excellent temporal control of the polymerization was illustrated by "ON/OFF" polymerizations, and natural sunlight was also used as an energy source. This novel CQDs-catalyzed miniemulsion photoATRP process may be easily extended to other aqueous dispersion RDRP systems. As an extension of our previous work (

Angewandte Chemie, Jun 24, 2021

Supporting information for this article is given via a link at the end of the document.

Polymer, May 1, 2019

The controlled polymerization of methacrylic monomers by nitroxide-mediated polymerization (NMP) ... more The controlled polymerization of methacrylic monomers by nitroxide-mediated polymerization (NMP) still represents a challenge in polymer science. This issue can be circumvented by the addition of a small amount of a comonomer known to exhibit a controlled character in NMP, the most representative example being styrene. The purpose of this work is to explore the use of 4-vinyl pyridine (4VP) as controlling comonomer, while conferring at the same time some functionality to the polymer chains. The NMP of methyl methacrylate (MMA), poly(ethylene glycol) methyl ether methacrylate (PEOMA 950 , M n = 950 g mol-1) and methacrylic acid (MAA) using a small amount of 4VP under mild experimental conditions (< 90 °C, atmospheric pressure), was investigated in this work. The copolymerization of MMA or PEOMA 950 with 10 mol% 4VP, mediated by the use of the BlocBuilder® alkoxyamine and a small amount of free nitroxide SG1, exhibited all the features of a controlled system in agreement with the favored incorporation of 4VP at the chain ends, leading to an efficient deactivation of the propagating radicals by the nitroxide SG1. In contrast, the polymerization of MAA was uncontrolled in the same conditions likely due to acid/base interaction between MAA and 4VP, affecting the reactivity of the functional comonomer. Consistently, the copolymerization of MAA with MMA also led to a progressive loss of control as the MAA content in the feed was increased. Among all the polymers synthesized, the P(MMA 72-co-4VP 10)-SG1 macroalkoyamine was then successfully used to reinitiate the copolymerization of n-butyl methacrylate (BMA) and 4VP both in solution and via dispersion polymerization in a mixture of ethanol and water. Finally, raspberry-like polymer/silica composite particles were prepared through nitroxide-mediated dispersion polymerization performed in the presence of silica nanoparticles, taking benefit of the strong acid-base interaction between 4VP and silica.

Aiche Journal, Mar 26, 2018

The production of latexes stabilized by solid particles, so-called Pickering stabilizers, has att... more The production of latexes stabilized by solid particles, so-called Pickering stabilizers, has attracted considerable attention due to its benefits, including the enhanced mechanical properties of the polymer films. Clays for instance were found to enhance particle stabilization in emulsion polymerization, in a comparable way to conventional surfactants. Their concentration thus determines the polymer particles size and number, and consequently the reaction rate. In this work, we investigate the impact of the presence of such rigid and big platelets at the polymer particle's surface on radical exchange between the aqueous phase and the polymer particles. It was found for the system underhand, that the average number of radicals per particle () was independent of the stabilizer layer. Therefore, a radical capture model independent of the clay concentration could be used to simulate reactions involving different clay concentrations and predict the evolution of the monomer conversion, particle size, and .

Applied Clay Science, Sep 1, 2016

Using Layered double hydroxides (LDH) nanoparticles and film-forming latexes, waterborne nanocomp... more Using Layered double hydroxides (LDH) nanoparticles and film-forming latexes, waterborne nanocomposite films were produced by simply a heterocoagulation and solvent casting process. Self-standing and transparent films with LDH contents from 2.5 to 15 vol% were prepared. The structure, microstructure and mechanical behavior were thoroughly investigated by powder X-ray diffraction (PXRD), infrared spectroscopy (IR), transmission electron microscopy (TEM), scanning electron microscopy (FIB-SEM) and dynamic mechanical analysis (DMA). Favorable electrostatic interactions between pristine LDH and the latex ensured a good dispersion of the bidimensional LDH platelets in the films. Above a certain content of LDH, the formation of a well-defined cellular LDH network following the starting latex morphology was observed. Such a percolating microstructure induces a large mechanical reinforcement significant of a mechanical percolation behavior.