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 binding‐triggered conformational change regulate many metabolic processes in living matter. Here, we have synergistically combined these two biorelevant processes to tune the Diels‐Alder (DA) reactivity of a synthetic self‐complexing host‐guest molecular switch CBPQT4+‐Fu, consisting of an electron‐rich furan unit covalently attached to the electron‐deficient cyclobis(paraquat‐p‐phenylene) tetrachloride (CBPQT4+, 4Cl‐) host. This design allows CBPQT4+‐Fu to efficiently compartmentalize the furan ring inside its host cavity in water, thereby protecting it from the DA reaction with maleimide. Remarkably, the self‐complexed CBPQT4+‐Fu 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

Elaboration de brosses de polymères à la surface du titane en vue d'applications biomédicales

L athérosclérose est une maladie vasculaire dont les complications sont la première cause de mortalité dans les pays développés. Pour soigner cette pathologie, une des méthodes les plus employées est l angioplastie couplée au stenting. Ce geste occasionne cependant de forts risques de complications postopératoires, dont la plus répandue est la resténose. Pour refreiner ce phénomène, différentes stratégie peuvent être exploitées, l une d elle consiste à immobilisé sur la surface du stent des composés bioactifs pour en faciliter l acceptation par l organisme. C est dans ce contexte que s inscrit cette étude. L idée première est de fonctionnaliser le titane, métal couramment dans le domaine médical, par des polymères pouvant être modifiés en quantité désirée par des molécules bioactives.Pour atteindre cet objectif, nous avons employé la polymérisation radicalaire contrôlée. Cet outil de choix permet d obtenir des polymères parfaitement définis comportant une fonctionnalité en extrémité de chaîne. Dans notre cas, nous avons choisi d y fixer une ancre catéchol, molécule naturelle ayant une forte affinité avec le titane. Différents polymères ont été conçus et, après caractérisation, ont été immobilisés sur le titane pour former des brosses. Les surfaces ainsi obtenues ont été caractérisée en termes de composition et de densité de fonctionnalisation. Enfin nous avons employé une molécule test, la glucosamine, pour modifier en différentes quantités une plateforme polymère, puis d évaluer biologiquement ces polymères en solution et immobilisés sur le titane pour en étudier l influence sur différentes lignées 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

Nouveaux récepteurs polytopiques à base de cyclodextrines pour la catalyse en phase aqueuse

Pour s affranchir des problèmes liés à l hydrophobie des alcènes terminaux dans des réactions d hydroformylation utilisant des catalyseurs organométalliques hydrosolubles, l association de polymères et de cyclodextrines (CDs) a été mise à profit pour concevoir de nouveaux additifs et de nouveaux milieux réactionnels. Trois combinaisons polymères/CDs ont été développées, soit par liaison covalente, soit par assemblage supramoléculaire. Premièrement, le greffage covalent de CDs partiellement méthylées sur des chaines polymères a permis d augmenter significativement les capacités de reconnaissance moléculaire des CDs vis-à-vis d alcènes 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. Deuxièmement, des hydrogels supramoléculaires composés de poly(éthylène) glycols et d a-CDs ont été utilisés avec succès en tant que milieu réactionnel dans des réactions d hydroformylation biphasique. Enfin, des nouveaux systèmes catalytiques dits intelligents ont été obtenus en additionnant les propriétés de reconnaissance moléculaire des CDs partiellement méthylées avec celles de polymères 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

Mécanismes élémentaires de plasticité des systèmes polymères amorphes (influence de la modification de la structure macromoléculaire par la chimie Click )

Les objectifs de cette thèse 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 copolymères parfaitement définis dotés de motifs furanes et la remarquable réactivité des azlactones vis-à-vis des amines. Les copolymères ont été synthétisés par polymérisation radicalaire contrôlée afin d obtenir des copolymères parfaitement définis fonctionnalisés en chaine latérale. Différents copolymères 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 copolymères à base d azlactones, nous avons montré que la nouvelle plateforme polymère était facilement modifiable par une grande variété d amines primaires permettant d élaborer de nouveaux matériaux avec des propriétés intéressantes (fluorescent, électroactif ). Les polymères fonctionnalisés ainsi obtenus ont été caractérisés par diverses techniques d analyses qui ont permis de traduire le caractère 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

Tunable UCST behaviour of a hydrophobic dialkoxynaphthalene-functionalized homopolymer based on reversible supramolecular recognition

Thermoresponsive polymers with reversible phase transition are appealing to various applications. Herein, we designed and synthesized a thermosensitive homopolymer bearing hydrophobic dialkoxynaphthalene moieties as polymer side chains that revealed UCST behaviour in pure ethanol and ethanol/water mixtures. It is reported that the complexation with the tetracationic macrocycle cyclobis(paraquat-p-phenylene) (CBPQT(4+)) host is strongly dependent on the degree of complexation due to steric hindrance and charge repulsion. Moreover, it was found that the cloud-point temperatures (T-CP) of the homopolymer could be modulated by host-guest complexation with CBPQT(4+) in alcohol-water solvent mixtures up to 6 equivalents of the host. When heated above the clearance-point temperatures, the homopolymer dissolves, but the host-guest interactions become unstable and are disrupted due to the effect of the solvent and the higher temperature. Subsequent cooling led to the collapse of the homopolymer, together with the reformation of the host-guest complexes resulting in a purple opaque solution. The tunable UCST approach may enable practical applications in the biomedical field or interactive smart materials

Intérêt des champignons telluriques dans des processus de bioremédiation de sols pollués 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 μg/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 réels problèmes pour l'environnement et la santé publique. Parmi les différentes techniques de réhabilitation actuellement disponibles, la bioremédiation s'est développée lors de ces dernières décades comme une alternative rentable et prometteuse. De nombreuses études ont mis en évidence l'aptitude des champignons de type lignolytique à dégrader les HAP. Cependant, l'origine non tellurique de ces champignons les rend peu compétitifs par rapport à la microflore endogène du sol. Dans une optique de bioremédiation, 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