Synthèse et caractérisation de nouveaux copolymères potentiellement autoassociatifs

Le sujet de cette étude consiste en la synthèse de nouveaux copolymères, associatifs en milieux aqueux, susceptibles d'encapsuler une protéine. Ces copolymères doivent être biocompatibles et biorésorbables pour une application biomédicale éventuelle et doivent de plus être amphiphiles. Le but de ce manuscrit est ainsi de décrire la synthèse de copolymères à blocs amphiphiles. L'association des blocs hydrophobes du copolymère doit en effet permettre la formation de particules en émulsion aqueuse. La partie hydrophobe des copolymères à blocs est constituée de polylactide synthétisé par polymérisation par ouverture de cycle du L-lactide. Le bloc hydrophile est constitué de poly(acide glutamique), peptide obtenu en deux étapes. On synthétise le poly(glutamate de benzyle) lors de la première étape par polymérisation par ouverture de cycle d'un anhydride de Leuchs, le N-carboxyanhydride de L-glutamate de benzyle. On déprotège ensuite les fonctions acide de ce polymère encore hydrophobe, le poly(glutamate de benzyle), pour obtenir le poly(acide glutamique), hydrophile. L'architecture du copolymère à blocs est obtenue à l'aide d'un amorceur difonctionnel qui amorce dans un premier temps la polymérisation du L-lactide. Le premier bloc de polylactide ainsi synthétisé possède en bout de chaîne un groupement susceptible d'amorcer la polymérisation du N-carboxyanhydride de L-glutamate de benzyle. On synthétise donc dans un deuxième temps le copolymère à blocs hydrophobes et on déprotège les fonctions acide du deuxième bloc pour obtenir le copolymère à blocs amphiphiles.The aim of this study is to synthesize new auto-associative copolymers in order to encapsulate a protein in water. These copolymers have to be biocompatible and bioassimilable for a possible biomedical application. Further more, they have to be amphiphilic. This document aims at describing the synthesis of amphiphilic bloc copolymers. The association of the hydrophobic blocs of the copolymer in water should entail to core-shell particle formation in aqueous emulsion. The hydrophobic part of the copolymers is a polylactide synthesized by ring opening polymerization of the L-lactide. The hydrophilic bloc is a poly(glutamic acid) peptide synthesized in two steps. We first synthesized a poly(benzyl glutamate) bloc by ring opening polymerization of a Leuch's anhydride, the N-carboxyanhydride of benzyl Lglutamate. Then we unprotect the acidic functions of this poly(benzyl glutamate), still hydrophobic polymer to yield the hydrophilic poly(glutamic acid). The architecture of this bloc copolymer is obtained thanks to a difunctionnal initiator that initiates the polymerization of the L-lactide in a first step. This polylactide first bloc has an end-group that can initiate the polymerization of the N-carboxyanhydride of benzyl Lglutamate. So we synthesize in a second step the hydrophobic bloc copolymer and we unprotect the acidic functions of the second bloc to yield the amphiphilic bloc copolymer

Tuning Structure and Rheology of Silica-Latex Nanocomposites with the Molecular Weight of Matrix Chains: A Coupled SAXS-TEM-Simulation Approach

The structure of silica-latex nanocomposites of three matrix chain masses (20, 50, and 160 kg/mol of poly(ethyl methacrylate)) are studied using a SAXS/TEM approach, coupled via Monte Carlo simulations of scattering of fully polydisperse silica nanoparticle aggregates. At low silica concentrations (1 vol. %), the impact of the matrix chain mass on the structure is quantified in terms of the aggregation number distribution function, highest mass leading to individual dispersion, whereas the lower masses favor the formation of small aggregates. Both simulations for SAXS and TEM give compatible aggregate compacities around 10 vol. %, indicating that the construction algorithm for aggregates is realistic. Our results on structure are rationalized in terms of the critical collision time between nanoparticles due to diffusion in viscous matrices. At higher concentrations, aggregates overlap and form a percolated network, with a smaller and lighter mesh in the presence of high mass polymers. The linear rheology is investigated with oscillatory shear experiments. It shows a feature related to the silica structure at low frequencies, the amplitude of which can be described by two power laws separated by the percolation threshold of aggregates

Comparative curing kinetics study of high char yield formaldehyde- and terephthalaldehyde-phenolic thermosets

International audienc

Epoxidized Oleic Acid‐Based Polymethacrylates as Viscosity Index Improvers

International audienc

Improvement of corrosion protection of steel by incorporation of a new phosphonated fatty acid in a phosphorus-containing polymer coating obtained by UV curing

tSix formulations containing diacrylate monomers (from 89 to 92.5% (w/w)) as well as a phosphonatedmethacrylate monomer (from 1 to 10% (w/w)) were prepared. All formulations were UV-cured and thecorrosion performance of the resulting coatings applied onto a steel substrate was assessed by elec-trochemical impedance spectroscopy (EIS). It was first shown that the coatings containing phosphonicacid methacrylate (MAPC1(OH)2) instead of methacrylate phosphonic dimethyl ester (MAPC1) presentedhigher corrosion protection related to the strong adhesive properties of phosphonic acid on the metalsubstrate. A minimum MAPC1(OH)2content of 2.5% was determined to provide the highest impedancevalues (best efficiency). Then, a new bio-based compound, i.e. phosphonic acid-bearing oleic acid (phos-phonated fatty acid), was synthesized and added as an inhibitor to the formulations. In the presence ofthis compound, the corrosion protection was notably improved. The beneficial effect of phosphonatedfatty acid was explained by its inhibitive action at the steel/coating interface and by the improvement ofthe barrier properties

Emulsion Polymerization of Dihydroeugenol-, Eugenol-, and Isoeugenol-Derived Methacrylates

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Atmospheric removal of methane by enhancing the natural hydroxyl radical sink

According to the latest report from the Intergovernmental Panel on Climate Change (IPCC), currently, global warming due to methane (CH4) alone is about 0.5°C while due to carbon dioxide (CO2) alone is about 0.75°C. As CH4 emissions will continue growing, in order to limit warming to 1.5˚C, some of the most effective strategies are rapidly reducing CH4 emissions and developing large scale CH4 removal methods. The aim of this review article is to summarise and propose possible methods for atmospheric CH4 removal, based on the hydroxyl radical (°OH), which is the principal natural sink of many gases in the atmosphere and on many water surfaces. Inspired by mechanisms of °OH generation in the atmosphere and observed or predicted enhancement of °OH by climate change and human activities, we proposed several methods to enhance the °OH sink by some physical means using water vapour and artificial UV radiation

Toward Sustainable Phenolic Thermosets with High Thermal Performances

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Neighboring Group Participation and Internal Catalysis Effects on Exchangeable Covalent Bonds: Application to the Thriving Field of Vitrimer Chemistry

Vitrimers constitute a fascinating class of polymer materials that make the link between the historically opposed 3D networks (thermosets) and linear polymers (thermoplastics). Their chemical resistance, reshaping ability, and unique rheological behavior upon heating make them promising for future applications in industry. However, many vitrimers require the use of high catalyst loadings, which raises concerns for their durability and limits their potential applications. To cope with this issue, internal catalysis and neighboring group participation (NGP) can be used to enhance the reshaping ability of such materials. A few studies report the effect of activating groups on the exchange reactions in vitrimers. Nevertheless, knowledge on this topic remains scarce, although research on vitrimers would greatly benefit from NGP already known in organic chemistry. The present Perspective presents the different types of exchangeable bonds implemented in vitrimers and discusses chemical groups known to have or potentially capable of an enhancing effect on exchange reactions. This analysis is underpinned by a thorough mechanistic discussion of the various exchangeable bonds presented