71 research outputs found
A water-soluble supramolecular polymeric dual sensor for temperature and pH with an associated direct visible readout
We report a multi-stimuli responsive polymeric sensor consisting of a pseudorotaxane-like architecture fabricated from a 1,5-diaminonaphthalene end-functionalized poly(N-isopropyl)acrylamide (Napht-N-PNIPAM) and cyclobis(paraquat-p-phenylene) (CBPQT4+,4Cl-). The coloured nature of the poly-pseudorotaxane provides a sensor for temperature and pH in water with an associated visible readout. To create this dual responsive polymeric sensor, a new chain transfer agent (Napht-N-CTA) incorporating a pH-responsive 1,5-diaminonaphthalene unit was synthesized and used for the polymerization of N-isopropylacrylamide via Reversible Addition-Fragmentation Chain Transfer (RAFT). The ability of Napht-N-PNIPAM to form a pseudorotaxane architecture with CBPQT4+,4Cl- in aqueous media was studied by means of UV-Vis, NMR (1H, 2D-ROESY, DOSY) and ITC experiments. Interestingly, the pseudorotaxane architecture can be reversibly dissociated upon either heating the sample above its cloud point or protonating the nitrogen atoms of the 1,5-diaminonaphthalene-based guest unit by adjusting the pH to around 1. ln both cases a dramatic colour change occurs from intense blue-green to colourless
Supramolecular polymer hydrogels induced by host-guest interactions with di-[cyclobis(paraquat-p-phenylene)] cross-linkers: from molecular complexation to viscoelastic properties
Supramolecular polymer networks have been designed on the basis of a -electron donor/acceptor complex: naphthalene (N)/cyclobis(paraquat-p-phenylene) (CBPQT4+=B). For this purpose, a copolymer of N,N-dimethylacrylamide P(DMA-N1), lightly decorated with 1 mol% of naphthalene pendant groups, has been studied in semi-dilute un-entangled solution in the presence of di-CBPQT4+ (BB) crosslinker type molecules. While calorimetric experiments demonstrate the quantitative binding between N and B groups up to 60 °C, the introduction of BB crosslinkers into the polymer solution gives rise to gel formation above the overlap concentration. From a comprehensive investigation of viscoelastic properties, performed at different concentrations, host/guest stoichiometric ratios and temperatures, the supramolecular hydrogels are shown to follow a Maxwellian behavior with a strong correlation of the plateau modulus and the relaxation time with the effective amount of interchain cross-linkers and their dissociation dynamics, respectively. The calculation of the dissociation rate constant of the supramolecular complex, by extrapolation of the relaxation time of the network back to the beginning of the gel regime, is discussed in the framework of theoretical and experimental works on associating polymers
Synergistic topological and supramolecular control of Diels-Alder reactivity based on a tunable self-complexing hos-guest molecular switch
International audienceCompartmentalization and bindingâtriggered conformational change regulate many metabolic processes in living matter. Here, we have synergistically combined these two biorelevant processes to tune the DielsâAlder (DA) reactivity of a synthetic selfâcomplexing hostâguest molecular switch CBPQT4+âFu, consisting of an electronârich furan unit covalently attached to the electronâdeficient cyclobis(paraquatâpâphenylene) tetrachloride (CBPQT4+, 4Clâ) host. This design allows CBPQT4+âFu to efficiently compartmentalize the furan ring inside its host cavity in water, thereby protecting it from the DA reaction with maleimide. Remarkably, the selfâcomplexed CBPQT4+âFu can undergo a conformational change through intramolecular decomplexation upon the addition of a stronger binding molecular naphthalene derivative as a competitive guest, triggering the DA reaction upon addition of a chemical regulator. Remarkably, connecting the guest onto a thermoresponsive lower critical solution temperature (LCST) copolymer regulator controls the DA reaction on command upon heating and cooling the reaction media beyond and below the cloud point temperature of the copolymer, representing a rare example of decreased reactivity upon increasing temperature. Altogether, this work opens up new avenues towards combined topological and supramolecular control over reactivity in synthetic constructs enabling control over reactivity through molecular regulators or even mild temperature variations
Nouveaux récepteurs polytopiques à base de cyclodextrines pour la catalyse en phase aqueuse
Pour s affranchir des problÚmes liés à l hydrophobie des alcÚnes terminaux dans des réactions d hydroformylation utilisant des catalyseurs organométalliques hydrosolubles, l association de polymÚres et de cyclodextrines (CDs) a été mise à profit pour concevoir de nouveaux additifs et de nouveaux milieux réactionnels. Trois combinaisons polymÚres/CDs ont été développées, soit par liaison covalente, soit par assemblage supramoléculaire. PremiÚrement, le greffage covalent de CDs partiellement méthylées sur des chaines polymÚres a permis d augmenter significativement les capacités de reconnaissance moléculaire des CDs vis-à -vis d alcÚnes possédant des chaines alkyles linéaires de plus de 12 carbones. La coopérativité entre CDs résultant de ce greffage covalent a conduit à une amélioration significative des performances catalytiques. DeuxiÚmement, des hydrogels supramoléculaires composés de poly(éthylÚne) glycols et d a-CDs ont été utilisés avec succÚs en tant que milieu réactionnel dans des réactions d hydroformylation biphasique. Enfin, des nouveaux systÚmes catalytiques dits intelligents ont été obtenus en additionnant les propriétés de reconnaissance moléculaire des CDs partiellement méthylées avec celles de polymÚres thermosensibles.To overcome the problems related to the hydrophobicity of terminal alkenes in hydroformylation reactions using water-soluble organometallic catalysts, the combination of polymers and cyclodextrins (CDs) has been exploited to develop new additives and new reaction media. Three combinations polymers/CDs have been developed, either covalently or by supramolecular assembly. First, the covalent grafting of partially methylated CDs on polymer chains significantly increased the capacity of molecular recognition of the CDs regarding alkenes with linear alkyl chains longer than 12 carbons. Cooperativity between CDs resulting from the covalent grafting led to a significant improvement in catalytic performance. Second, supramolecular hydrogels composed of poly(ethylene) glycol and a-CDs have been successfully used as a reaction medium in biphasic hydroformylation reactions. Finally, new "smart" catalytic systems have been obtained by summing the molecular recognition properties of partially methylated CDs with those of thermosensitive polymers.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF
Elaboration de brosses de polymÚres à la surface du titane en vue d'applications biomédicales
L athĂ©rosclĂ©rose est une maladie vasculaire dont les complications sont la premiĂšre cause de mortalitĂ© dans les pays dĂ©veloppĂ©s. Pour soigner cette pathologie, une des mĂ©thodes les plus employĂ©es est l angioplastie couplĂ©e au stenting. Ce geste occasionne cependant de forts risques de complications postopĂ©ratoires, dont la plus rĂ©pandue est la restĂ©nose. Pour refreiner ce phĂ©nomĂšne, diffĂ©rentes stratĂ©gie peuvent ĂȘtre exploitĂ©es, l une d elle consiste Ă immobilisĂ© sur la surface du stent des composĂ©s bioactifs pour en faciliter l acceptation par l organisme. C est dans ce contexte que s inscrit cette Ă©tude. L idĂ©e premiĂšre est de fonctionnaliser le titane, mĂ©tal couramment dans le domaine mĂ©dical, par des polymĂšres pouvant ĂȘtre modifiĂ©s en quantitĂ© dĂ©sirĂ©e par des molĂ©cules bioactives.Pour atteindre cet objectif, nous avons employĂ© la polymĂ©risation radicalaire contrĂŽlĂ©e. Cet outil de choix permet d obtenir des polymĂšres parfaitement dĂ©finis comportant une fonctionnalitĂ© en extrĂ©mitĂ© de chaĂźne. Dans notre cas, nous avons choisi d y fixer une ancre catĂ©chol, molĂ©cule naturelle ayant une forte affinitĂ© avec le titane. DiffĂ©rents polymĂšres ont Ă©tĂ© conçus et, aprĂšs caractĂ©risation, ont Ă©tĂ© immobilisĂ©s sur le titane pour former des brosses. Les surfaces ainsi obtenues ont Ă©tĂ© caractĂ©risĂ©e en termes de composition et de densitĂ© de fonctionnalisation. Enfin nous avons employĂ© une molĂ©cule test, la glucosamine, pour modifier en diffĂ©rentes quantitĂ©s une plateforme polymĂšre, puis d Ă©valuer biologiquement ces polymĂšres en solution et immobilisĂ©s sur le titane pour en Ă©tudier l influence sur diffĂ©rentes lignĂ©es de cellules.Atherosclerosis is a vascular disease, whose complications are the first cause of death in developed countries. In order to cure this pathology, angioplasty, coordinated with stenting, is nowadays one of the most used treatment. However, postsurgical complications can often occur with this surgery technique. The frequency of restenosis, the most common complication, could be decreased thanks to different strategies. One of these strategies is to graft on stent surface bioactive molecules that enhance biocompatibility.In this context with have endeavored to functionalize titanium, commonly used in medical applications, with polymers that can bear bioactive molecules. In order to reach this goal, we used controlled radical polymerization, which can provide end-functionalized, well-defined polymers. In our case, we have chosen to craft polymers with a catechol at the chain end, a natural anchor which have good affinity with titanium. During this study, different kind of polymers have been built and analyzed. Then, they were grafted to titanium substrates to create polymer brushes. Grafting densities and surfaces compositions were characterized thanks to different techniques. Finally, we tried to modify a polymeric platform with different quantities of glucosamine, a test molecule. These polymers were then biologically evaluated alone and grafted to titanium with different cell lines.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF
Mécanismes élémentaires de plasticité des systÚmes polymÚres amorphes (influence de la modification de la structure macromoléculaire par la chimie Click )
Les objectifs de cette thÚse portent sur l élaboration de nouveaux matériaux réticulés réversibles et sur la compréhension de leurs propriétés mécaniques. Pour atteindre ces objectifs, nous avons exploité deux stratégies : la réaction de Diels-Alder (DA) à partir de copolymÚres parfaitement définis dotés de motifs furanes et la remarquable réactivité des azlactones vis-à -vis des amines. Les copolymÚres ont été synthétisés par polymérisation radicalaire contrÎlée afin d obtenir des copolymÚres parfaitement définis fonctionnalisés en chaine latérale. Différents copolymÚres réticulés ont été préparés via la réaction de DA et caractérisés en termes de température de transition vitreuse et de taux de gonflement. L étude de leurs propriétés thermiques et viscoélastiques a mis en évidence une influence de la réticulation. Dans un second temps, les propriétés telles que leur réversibilité et leur comportement mécanique ont été étudiées. Nous avons défini l existence d une relation entre les mécanismes de plasticité et l évolution structurale induite. Concernant les copolymÚres à base d azlactones, nous avons montré que la nouvelle plateforme polymÚre était facilement modifiable par une grande variété d amines primaires permettant d élaborer de nouveaux matériaux avec des propriétés intéressantes (fluorescent, électroactif ). Les polymÚres fonctionnalisés ainsi obtenus ont été caractérisés par diverses techniques d analyses qui ont permis de traduire le caractÚre quantitatif de la réaction. Enfin, des matériaux réticulés ont également été élaborés par la réaction des motifs azlactones avec un composé diamine.The main objectives of this work were the elaborate new reversible crosslinked materials and to get a better understanding of their physical and mechanical properties. Two strategies have been investigated to prepare such materials. The first one consisted in applying to well-defined furan functionalized side-chain copolymers the Diels-Alder (DA) / retroDiels-Alder reactions. The second approach was based on the high reactivity of azlactone units embedding in well-defined copolymer chains toward primary amines. The controlled radical polymerization has been exploited in order to provide an effective way for the control synthesis of the well-defined side-chain functionalized copolymers. Then, various crosslinked materials have been prepared using the DA reaction and characterized to determine their glass transition temperature and their swelling ratio. The study of their thermal and viscoelastic properties highlighted the deep impact of the crosslinking. Then, their reversible and mechanical behaviors were investigated and we observed a correlation between the plastic deformation mechanisms and the induced structural evolution. Concerning the azlactone based copolymer, we have shown that this new polymeric platform could be efficiently modified by various primary amines, affording new materials with interesting properties (fluorescence, electroactive, ). The ring-opening reactions of azlactone functionalized copolymers were fully characterized proving the quantitative character of this reaction. Endly, crosslinked materials have been also elaborated by treating the azlactone copolymer with a diamino component.LILLE1-Bib. Electronique (590099901) / SudocSudocFranceF
IntĂ©rĂȘt des champignons telluriques dans des processus de bioremĂ©diation de sols polluĂ©s par des hydrocarbures aromatiques polycycliques
Polycyclic aromatic hydrocarbons (PAH) are ubiquitous and persistent pollutants that cause great environmental and health concern, because of their genotoxic and carcinogenic properties. Among the processes whereby these compounds are removed from the environment, microbial degradation plays a major role in the remediation of contaminated sites. Numerous biodegradation studies have been done on fungi, especially on various white rot fungi such as Phanerochaete chrysosporium, under in vitro and in vivo conditions. The installation of these foreign fungi in non-sterile soils is quite hazardous due to intense negative interactions with indigenous soil microorganisms. Optimising the degradation of PAH by the indigenous microbial community that had already been adapted to the soil habitat would be probably more economical and equally efficient. In our studies, we focused therefore on the ability of telluric fungi for PAH field bioremediation processes. In particular, we isolated a Deuteromycete fungus Fusarium solani that was able to grow in liquid medium with benzo[a]pyrene as sole carbon source and to mineralise this PAH. In a batch fermentor, [7,10-14C]benz[a]pyrene mineralization occurred rapidly at early stages of fermentation (15 hr) during the germination of fungal spores and was not a continuous process as mineralization occurred in a biphasic pattern. Moreover, Fusarium solani showed an average rate of mineralization about 65 ÎŒg/g dry weight/day within 11 days of incubation, comparable as mineralization rate obtained with a white rot fungus Phanerochaete chrysosporium.Les hydrocarbures aromatiques polycycliques (HAP) sont des polluants ubiquistes et persistants dont certains posent de rĂ©els problĂšmes pour l'environnement et la santĂ© publique. Parmi les diffĂ©rentes techniques de rĂ©habilitation actuellement disponibles, la bioremĂ©diation s'est dĂ©veloppĂ©e lors de ces derniĂšres dĂ©cades comme une alternative rentable et prometteuse. De nombreuses Ă©tudes ont mis en Ă©vidence l'aptitude des champignons de type lignolytique Ă dĂ©grader les HAP. Cependant, l'origine non tellurique de ces champignons les rend peu compĂ©titifs par rapport Ă la microflore endogĂšne du sol. Dans une optique de bioremĂ©diation, nous avons conduit des travaux de recherche afin d'utiliser le potentiel biotechnologique de champignons telluriques et en particulier de Fusarium solani
Effect of host-guest complexation on the thermoresponsive behavior of poly(oligo ethylene glycol acrylate)s functionalized with dialkoxynapththalene guest side chains
The combination of thermoresponsive polymers with supramolecular host-guest interactions enables accurate tuning of the phase transition temperature, while also providing additional response mechanisms based on host-guest complexation. Most studies focused on a single thermoresponsive polymer to demonstrate the effect of host-guest complexation on the responsive behavior. In this work, the effect of the polymer structure on the host-guest complexation and thermoresponsive behavior is reported. Therefore, different poly(oligoethylene glycol acrylate)s, namely, poly(2-hydroxyethylacrylate) (PHEA), poly(methoxy diethylene glycol acrylate), poly(methoxy triethylene glycol acrylate), and poly(methoxy tetraethylene glycol acrylate), are synthesized functionalized with 1,5-dialkoxynaphthalene guest molecules in the side chain. Their complexation with the cyclobis(paraquat-p-phenylene) tetrachloride host is studied to understand the effect of polymer structure on the supramolecular association and the polymer phase transition, revealing that the oligoethylene glycol side chains lead to weaker host-guest complexation and also have a smaller increase in the cloud point temperature compared to PHEA
Supramolecular control over thermoresponsive polymers
Thermoresponsive polymers facilitate the development of a wide range of applications in multiple areas spanning from construction or water management to lab-on-a-chip technologies and biomedical sciences. The combination of thermoresponsive polymers with supramolecular chemistry, inspired by the molecular mechanisms behind natural systems, is resulting in adaptive and smart materials with unprecedented properties. This work reviews the past advances on the combination of this young field of research with polymer chemistry that is enabling a high level of control on polymer architecture and stimuli-responsiveness in solution. We will discuss how such polymer systems are able to store thermal information, respond to multiple stimuli in a reversible manner, or adapt their morphology on demand, all powered by the synergy between polymer chemistry and supramolecular chemistry
Elaboration de plateformes biomimétiques à base de dopamine pour la fonctionnalisation du titane
L'étude concerne la fonctionnalisation de surfaces à base de titane à partir d'une ancre chimique biomimétique modifiable chimiquement, la dopamine, dans le but de concevoir des biomatériaux utilisables en tant que dispositifs implantables. Deux approches différentes de greffage par la stratégie «graft to» sont proposées. La premiÚre consiste en la synthÚse et l'immobilisation sur les surfaces de titane de polymÚres parfaitement définis et stimulables fonctionnalisés par un motif catéchol en extrémité de chaßne. La seconde propose de modifier préalablement la surface par une ancre chimique spécifique intégrant un motif catéchol d'une part et un motif furane ou maléimide d'autre part permettant d'engager sur demande une réaction réversible de cycloaddition de type Diels Alder (DA) avec une large gamme de molécules ou polymÚres fonctionnalisés par l'entité complémentaire
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