A One-Step Strategy for End-Functionalized Donor–Acceptor Conjugated Polymers

A modular and robust method for preparing end-functionalized donor–acceptor (D–A) narrow bandgap conjugated polymers is reported that avoids multistep reactions and postpolymerization modification. The strategy is well-controlled and affords functional materials with predictable molecular weight and high end-group fidelity. To exemplify this synthetic strategy, narrow bandgap conjugated polymers based on PDPP2FT were prepared that contain perylene diimide (PDI) units at the chain-ends. Monte Carlo simulations confirm the high degree of chain-end functionalization while photoluminescence studies reveal the unique photophysical properties of the end-functional polymers with efficient charge transfer occurring between the main polymer chain and PDI end-groups that results exclusively from their covalent linkage

A One-Step Strategy for End-Functionalized Donor–Acceptor Conjugated Polymers

A modular and robust method for preparing end-functionalized donor–acceptor (D–A) narrow bandgap conjugated polymers is reported that avoids multistep reactions and postpolymerization modification. The strategy is well-controlled and affords functional materials with predictable molecular weight and high end-group fidelity. To exemplify this synthetic strategy, narrow bandgap conjugated polymers based on PDPP2FT were prepared that contain perylene diimide (PDI) units at the chain-ends. Monte Carlo simulations confirm the high degree of chain-end functionalization while photoluminescence studies reveal the unique photophysical properties of the end-functional polymers with efficient charge transfer occurring between the main polymer chain and PDI end-groups that results exclusively from their covalent linkage

Mise en œuvre de liaisons réversibles covalentes et non-covalentes pour de nouveaux matériaux polymères recyclables et retransformables.

Incorporating reversible bonds in polymer materials is an attractive method for obtaining crosslinked networks, that can still be reshaped or recycled after use. In the scope of this thesis, we synthesized and studied polymer networks maintained through two distinct types of reversible bonds: non-covalent hydrogen bonds and covalent ester bonds able to be exchanged through trans-esterification reactions. In a first section we report the synthesis of different types of supramolecular polymers from fatty acid derivatives, epoxy resins and polyethers. These polymers are modified with a supramolecular moiety (imidazolidone) able to strongly self-associate through multiple hydrogen bonding. Some of these polymers display the surprising ability to self-heal when broken parts are put in contact for a few minutes. A rheological study is carried out in order to characterize the effect of supramolecular groups on the mechanical properties of the materials. In a second section we study epoxy-based materials. Such materials are known to be irreversibly crosslinked after cured. However, when modified in order to allow for some exchanges of ester bonds, the materials can be ground then extruded, or thermoformed even after complete curing.L'incorporation de liaisons réversibles dans des matériaux polymères constitue une méthode attrayante pour obtenir des réseaux réticulés, qui peuvent cependant être retransformés ou recyclés après utilisation. Au cours de cette thèse, nous avons synthétisé et étudié des réseaux polymères maintenus par deux types distincts de liaisons réversibles : les liaisons hydrogène (non-covalentes) et les liaisons ester (covalentes, mais susceptibles de s'échanger par trans-estérification). Dans une première partie sont synthétisés différents types de polymères supramoléculaires à base de dérivés d'acides gras d'origine végétale, de résines époxydes et de polyéthers. Ces polymères sont modifiés avec un groupement fonctionnel (imidazolidone) capable de s'associer fortement par des liaisons hydrogène multiples. Certains de ces polymères présentent l'étonnante capacité de pouvoir s'auto-réparer par simple mise en contact une fois cassés. Une étude rhéologique des différents systèmes est réalisée afin de caractériser l'effet des groupes supramoléculaires sur les propriétés mécaniques. Dans une seconde partie, des matériaux à base de résine époxyde, réputée pour durcir irréversiblement, sont modifiés afin de permettre des échanges de liaisons ester. En conséquence, les matériaux obtenus après réticulation peuvent encore être remis en forme par broyage, puis injection ou par thermoformag

Use of reversible covalent and non-covalent bonds in new recyclable and reprocessable polymer materials

PARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Polyethylene Aerogels with Combined Physical and Chemical Crosslinking: Improved Mechanical Resilience and Shape-Memory Properties

International audienc

Synthesis, Recycling and High‐Throughput Reprocessing of Phase‐Separated Vitrimer‐Thermoplastic Blends

Phase‐separated polymer blends including a transesterification vitrimer and polypropylene are synthesized from widely available precursors through reactive processing. It is shown that proper formulation during the process including a viscosity modifier of the vitrimer precursors and a reactive interface compatibilizer yields well‐dispersed vitrimer phases with fractions up to 75 wt.% in the polypropylene phase. These vitrimer blends can be easily reprocessed by multiple shredding‐injection cycles and processed in high‐shear conditions through capillary rheometry. Rheological analyses reveal that a percolating dynamic network is formed across the vitrimer domains. It breaks apart during high shear reprocessing of the material and dynamically reforms after thermal annealing of the blends. It therefore ideally combines the mechanical and high‐throughput (re)processing properties of the thermoplastic matrix minor phase with the chemical, thermomechanical, and dynamic properties of the vitrimer major phase. This work illustrates the decoupling of processing at high shear rates enabled by the polypropylene processing aid from the kinetics of dynamic exchanges of the vitrimer phase and thermomechanical properties at the service temperature of the blends

Expanding the structural variety of poly(1,2,3-triazolium)s obtained by simultaneous 1,3-dipolar Huisgen polyaddition and N-alkylation

International audienceA series of six 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) having random distributions of 1,3,4- and 1,3,5-trisubstituted 3-methyl-1,2,3-triazolium units are prepared by the solvent-and catalyst-free 1,3-dipolar Huisgen cycloaddition of two alpha-azide-omega-alkyne monomers and simultaneous N-alkylation of the resulting 1,4- and 1,5-disubstituted poly(1,2,3-triazole)s by N-methyl bis(trifluoromethylsulfonyl)imide (TFSI), trimethyl phosphate or methyl methanesulfonate quaternizing agents. The physical and ion conducting properties of this series of TPILs having TFSI, dimethyl phosphate (DMP) or methanesulfonate (MSF) anions are discussed based on solubility, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), size exclusion chromatography (SEC) and broadband dielectric spectroscopy (BDS) measurements

Tuning the Viscosity Profile of Ionic Vitrimers Incorporating 1,2,3-Triazolium Cross-Links

International audienceVitrimers are dynamic polymer networks with unique viscoelastic behavior combining the best attributes of thermosets and thermoplastics. Ionic vit-rimers are a recent class of dynamic materials, where 1,2,3-triazolium cross-links are reshuffled by trans-N-alkylation exchange reactions. Comparison of dynamic properties with a selection of vitrimers relying on different exchange reactions highlights the particularly high viscous flow activation energies of trans-N-alkylation reactions, thus providing an enhanced compromise between fast reprocessing at moderately high temperatures and low creep at service temperature. Varying the [monomer]/[cross-linker] ratio in the initial formulation of these 1,2,3-triazolium-based networks affords a fine tuning of their viscosity profiles. Confrontation of rheometry and X-ray photoelectron spectroscopy data allows the correlation of variations in chemical composition with changes in the covalent exchange dynamics. This unprecedented approach enables the proposition of a dissociative two-step mechanism for the trans-N-alkylation of 1,2,3-triazoliums initiated by a nucleophilic attack of the 1,2,3-triazolium cross-links by the iodide counteranion, yielding uncrosslinking by deN -alkylation. Subsequent rapid re-N-alkylation of the formed 1,2,3-triazole by surrounding iodide-functionalized dangling chains affords exchange of the cross-link position. This study highlights that strictly associative exchange reactions are not compulsory to induce vitrimer behavior, and may pave the way to a much wider variety of vitrimers relying on conventional reversible covalent reactions

Reprocessing and Recycling of Highly Cross-Linked Ion-Conducting Networks through Transalkylation Exchanges of C-N Bonds

International audienceExploiting exchangeable covalent bonds as dynamic cross-links recently afforded a new class of polymer materials coined as vitrimers. These permanent networks are insoluble and infusible, but the network topology can be reshuffled at high temperatures, thus enabling glasslike plastic deformation and reprocessing without depolymerization. We disclose herein the development of functional and high-value ion-conducting vitrimers that take inspiration from poly(ionic liquid)s. Tunable networks with high ionic content are obtained by the solvent- and catalyst-free polyaddition of an alpha-azide-omega-alkyne monomer and simultaneous alkylation of the resulting poly(1,2,3-triazole)s with a series of difunctional cross-linking agents. Temperature-induced transalkylation exchanges of C-N bonds between 1,2,3-triazolium cross-links and halide-functionalized dangling chains enable recycling and reprocessing of these highly cross-linked permanent networks. They can also be recycled by depolymerization with specific solvents able to displace the transalkylation equilibrium, and they display a great potential for applications that require solid electrolytes with excellent mechanical performances and facile processing such as supercapacitors, batteries, fuel cells, and separation membranes

UV-Patterning of Ion Conducting Negative Tone Photoresists Using Azide-Functionalized Poly(Ionic Liquid)s

International audienceThe patterning of solid electrolytes that builds upon traditional fabrication of semiconductors is described. An azide-, functionalized poly(1,2,3-triazolium ionic liquid) is used as an ion conducting negative tone photoresist. After UV-irradiation through an optical mask, micron-scaled, patterned, solid polyelectrolyte layers with controlled sizes and shapes are obtained. Furthermore, alkylation of poly(1,2,3-triazole)s can be generalized to the synthesis of poly(ionic liquid)s with a tunable amount of pendant functionalities