Synthesis and characterization of stimuliresponsive copolymers based on N,N-diethylacrylamide

Ce travail de thèse concerne la synthèse et la caractérisation d'homo et de copolymères stimulables à base de N,N-diéthylacrylamide (DEAm). Des homopolymères ont été préparés par polymérisation radicalaire contrôlée par transfert réversible par addition-fragmentation (RAFT). Cette polymérisation a été conduite en présence de trois agents de transfert différents et s'est avérée contrôlée quelles que soient les conditions expérimentales. Deux types de copolymères ont ensuite été préparés, de type PEG-b-PDEAm et PDEAm-b-polypeptides par polymérisation RAFT et combinaison RAFT/ polymérisation par ouverture de cycle (ROP), respectivement. Ces copolymères double hydrophiles ont été caractérisés et leur comportement en solution aqueuse a été évalué. Nous avons montré la formation de micelles c?ur-couronne au dessus de la LCST. Nous avons également développé une stratégie de synthèse originale dans le cas des PDEAm-b-polypeptides puisque la ROP a été réalisée en utilisant un macroamorceur de type thiol. Après déprotection des copolymères sensibles au pH et à la température ont été obtenus et montre des propriétés de structuration différentes en fonction de ces deux stimuli.This manuscript deals with the synthesis and characterization of responsive copolymers containing N,N-diethylacrylamide (DEAm). Homopolymers were prepared by controlled radical polymerization, especially Reversible Addition-Fragmentation Transfer (RAFT). Polymerization was achieved using three different chain transfer agents and was controlled whatever the experimental conditions. PEG-b-PDEAm and PDEAm-b-polypeptides were synthesized by RAFT polymerization and RAFT/Ring Opening Polymerization (ROP) respectively. These double hydrophilic block copolymers were characterized and their behavior in aqueous solution was evaluated. We showed that core/corona micelles were obtained above the lower critical solution temperature. We also developed a new strategy for the synthesis of PDEAm-b-polypeptides as ROP was achieved using a thiol macroinitiator. After deprotection pH- and thermo-sensitive copolymers were afforded which proved different structuration as a function of both stimuli.MONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Rapid and Controlled Organocatalyzed Ring-Opening Polymerization of 3S-(Isobutyl)morpholine-2,5-dione and Copolymerization with Lactide

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Noncovalent coatings for the separation of synthetic polypeptides by nonaqueous capillary electrophoresis

International audienceRecently, we demonstrated the possibility to extend the range of capillary electrophoresis (CE) applications to the separation of non-water-soluble synthetic polymers. This work focuses on the control of the electroosmotic flow (EOF) and on the limitation of the solute adsorption in nonaqueous electrolytes. For these purposes, different strategies were investigated. For the initial, a viscous additive (ethylene glycol or glycerol) was used in the electrolyte in order to decrease the EOF magnitude and, possibly, to compete with solute adsorption. A second strategy was to modify, before separation, the fused-silica capillary wall by the adsorption of poly(ethylene oxide) (PEO) via hydrogen bonding. The influence of the molecular mass of the adsorbed PEO on the EOF magnitude and direction was studied in electrolytes based on methanol/acetonitrile mixtures containing ammonium ions. For PEO molecular masses above ,1000 g/ mol, reversed (anodic) EOF were reported in accordance with previous results obtained with PEO covalently bonded capillaries. The influence of the nature and the concentration of the background electrolyte cation on the EOF magnitude and direction were also investigated. A third strategy consisted in modifying the capillary wall by the adsorption of a cationic polyelectrolyte layer. Advantageously, this polyelectrolyte layer suppressed the adsorption of the polymer solutes onto the capillary wall. The results obtained in this work confirm the high potential and the versatility of CE for the characterization of ionizable organic polymers in nonaqueous media

RAFT polymerization of N,N-diethylacrylamide: Influence of chain transfer agent and solvent on kinetics and induction period

International audienceRAFT polymerization of N,N-diethylacrylamide was achieved using three different chain transfer agents bringing cyanoisopropyl, cumyl, or tert-butyl R groups, in different solvents (dioxane, toluene), or in bulk. Reactions were controlled and allowed the synthesis of poly(N,N-diethylacrylamide) with targeted molecular weights. Best results were obtained with cyanoisopropyl dithiobenzoate at 80 °C in toluene. This chain transfer agent (CTA) led to the highest efficiency with a very short induction period. On the reverse, cumyl and tert-butyl dithiobenzoates led to relatively high induction periods which were explained by the slow fragmentation of the intermediate radicals and/or the presence of irreversible termination reactions. Initialization process was also discussed. Cumyl dithiobenzoate surprisingly gave the highest induction in comparison with other CTAs and the slowest polymerization rate in all reactional media. Finally, we demonstrated that the induction period was influenced by the solvent

Synthesis of polypeptide/inorganic hybrid block copolymers

International audiencePolypeptide/inorganic hybrid copolymers were obtained by a four-step synthetic approach combining (i) atom transfer polymerization of tert-butyl acrylate, (ii) chemical modification of the bromo end groups of ATRP-polymers into primary amino group using Gabriel reaction, (iii) ring opening polymerization of Nε-trifluoroacetyl-l-lysine or γ-benzyl-l-glutamate N-carboxyanhydrides followed by (iv) the transamidification reaction using a large excess of (3-aminopropyl)trimethoxysilane to substitute the tert-butyl groups of the poly(tert-butyl acrylate) block. Products were characterized using 1H NMR, FT-IR, DSC and MALDI-TOF MS. These techniques proved that polymerization of tert-butyl acrylate was controlled whatever the molecular weight targeted and that bromide was quantitatively converted to amino end group by a original method leading to the synthesis of copolymers in the presence of N-carboxyanhydrides as monomers. Amphiphilic polypeptide/inorganic hybrid copolymers were then achieved. Polypeptide/inorganic hybrid copolymers were obtained by a four-step synthetic approach combining (i) atom transfer polymerization of tert-butyl acrylate, (ii) chemical modification of the bromo end groups of ATRP-polymers into primary amino group using Gabriel reaction, (iii) ring opening polymerization of Nε-trifluoroacetyl-l-lysine or γ-benzyl-l-glutamate N-carboxyanhydrides followed by (iv) the transamidification reaction using a large excess of (3-aminopropyl)trimethoxysilane to substitute the tert-butyl groups of the poly(tert-butyl acrylate) block. Products were characterized using 1H NMR, FT-IR, DSC and MALDI-TOF MS. These techniques proved that polymerization of tert-butyl acrylate was controlled whatever the molecular weight targeted and that bromide was quantitatively converted to amino end group by a original method leading to the synthesis of copolymers in the presence of N-carboxyanhydrides as monomers. Amphiphilic polypeptide/inorganic hybrid copolymers were then achieved

Syntheses of donor acceptor biobased photocurable water-soluble resins based on poly-L-lysine

International audienceWe report a new kind of coating using UV waterborne technique with a biobased poly(amino acid) resin. Firstly we performed the thermal polycondensation of L-lysine during 15 hours at 150 °C in order to synthesize water-soluble oligomers of poly-L-lysine (PLL) with 5-6 monomer units. These oligomers were then transformed in mild conditions to give photocurable water-soluble resins. We grafted on the poly-L-lysine backbone, allyl and maleamic acid functional groups, with a grafting rate close to 65% thanks to allyl glycidyl ether and maleic anhydride respectively. The influence of the reaction time and the reagents ratio on the grafting rate was investigated. Hence, the donor/acceptor photopolymerization of the mixture of allyl ether-poly-L-lysine (PLL-g-AE) with maleamic acid-poly-L-lysine (PLL-g-MA) in aqueous solution gave yellow transparent films. The degree of conversion and other kinetic parameters have been studied and detailed. This work contributes to the development of materials based on renewable resources and cleaner processes. It opens a new pathway to both fundamental and applied-driven research

Simple and Rapid Mechanochemical Synthesis of Lactide and 3S-(Isobutyl)morpholine-2,5-dione-Based Random Copolymers Using DBU and Thiourea

International audienceThere is a growing interest surrounding morpholine-2,5-dione-based materials due to their impressive biocompatibility as well as their capacity to break down by hydrolytic and enzymatic pathways. In this study, the ring-opening (co)polymerization of leucine-derived 3S-(isobutyl)morpholine-2,5-dione (MD) and lactide (LA) was performed via ball-milling using a catalytic system composed of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 3-[3,5-bis(trifluoromethyl)phenyl]-1-cyclohexylthiourea (TU). Once the homopolymerizations of MD and LA optimized and numerous parameters were studied, the mechanochemical ring-opening copolymerization of these monomers was explored. The feasibility of ring-opening copolymerizations in mechanochemical systems was demonstrated and a range of P(MD-co-LA) copolymers were produced with varying proportions of MD (23%, 48%, and 69%). Furthermore, the beneficial cocatalytic effects of TU with regards to ROP control were found to be operative within mechanochemical systems. Further parallels were observed between solution- and mechanochemical-based ROPs

A New Route for the Modification of Halogen End Groups to Amino End-Functionalized Poly(tert-butyl acrylate)s

International audienceThe synthesis of primary amine end-functional poly(tert-butyl acrylate)s has been achieved by using the Gabriel reaction. Polymerization of tert-butyl acrylate was first achieved by atom transfer radical polymerization using ethyl-2-bromoisobutyrate or paramethoxyphenyl-2-bromoisobutyrate as initiator. Both resulting polymers, with a bromide-end atom, were converted into phthalimido intermediates which then were successfully hydrolyzed using potassium hydroxide in tert-butyl alcohol to result in poly(tert-butyl acrylate)s terminated by a primary amine function. End group interconversions were followed by 1H NMR, FT-IR, and MALDI-TOF MS measurements. All the results proved that quantitative transformations were achieved at each step. Moreover, the method developed is very easy to carry out

Novel Strategy for ROP of NCAs Using Thiols As Initiators: Synthesis of Diblock Copolymers Based on Polypeptides

International audienceThe ring opening polymerization (ROP) of γ-benzyl-L-glutamate N-carboxyanhybride (BLG-NCA) and Nε-trifluroactetyl-L-lysine N-carboxyanhybride (TFALys-NCA) by thiol was investigated at 0°C in DMF as solvent. The use of 2-(trimethylsilyl)-ethanethiol as initiator and its incorporation in the macromolecular chain showed the efficient ring opening polymerization of BLG-NCA by the so called “amine” mechanism. Thus, we proposed a novel synthetic pathway for the synthesis of diblock copolypeptides [poly(N,Ndiethylacrylamide)- b-poly(γ-benzyl-L-glutamate) and poly(N,N-diethylacrylamide)-bpoly( Nε-trifluoroacetyl-L-lysine)] using thiol based macroinitiator. This last was obtained by cleavage of a dithioester end group of poly(N,N-diethylacrylamide) synthesized by RAFT polymerization