The covalent bond formed between a N-heterocyclic carbene and an aryl-isothiocyanate was discovered to be thermally-reversible. This bond was incorporated into the backbone of an aromatic polymer which, when subjected to heat and excess monomer, would depolymerize to smaller oligomers. In addition these small molecules contain active chain ends and could be repolymerized to reform the original polymer. The high molecular weight material was made into freestanding sheets with desirable mechanical properties and could be made conductive by treatment with iodine. A new poly(triazene) was formed from the reaction of a facially opposed, annulated, bis-N-heterocyclic carbene (NHC) and an organic bis-azide. The NHC as well as the azide were varied and combined to produce a series of polymers which were characterized by GPC, TGA, and NMR. These thermally robust polymers were also coated onto glass slides and rendered electrically conductive by exposure to iodine vapor. A new reagent for Reversible Addition Fragmentation Chain Transfer Polymerization (RAFT) is described. This imidazolium based reagent shows unusually fast kinetics which allows it to control polymerizations at significantly reduced loadings compared to the more traditional neutral dithiocarbamates or dithioesters. The fast kinetics is explained by the rapid rotation of the dithioester about the plane of the cationic N-heterocycle. Sulfonated poly(ether ether ketone) (sPEEK) membranes were blended with imidazoles with varying pKas. The proton conductivity of the membranes was evaluated as a function of pKa and temperature. Interestingly, the conductivity of the dry membranes showed a non-monotonous profile over a temperature range of 25 – 150 C. We use a theoretical model to better understand the mechanistic origins of the observed temperature–conductivity profiles. This model is based on the reaction equilibria between sPEEK’s sulfonic acid groups and the basic sites of the added heterocycles. Using the copper-catalyzed 1,3-dipolar “click” cycloaddition reaction, poly(sulfone)s containing pendant azide moieties were functionalized with various amounts of sodium 3-(prop-2-ynyloxy)propane-1-sulfonate and crosslinked with 1,7-octadiyne. The degree of sulfonation as well as the degree of cross-linking was systematically varied by changing the ratios of the aforementioned reagents. The polymers were cast into membranes, acidified, and then tested for proton conductivity, methanol permeability, and membrane-electrode assembly (MEA) performance. / text

Le présent travail de recherche vise à mieux connaître les interactions au sein d'auto-assemblages petites molécules – ADN dans le but de faciliter la conception de futurs ligands ou vecteurs de l'ADN. Pour se faire, des composés guanidiniums, sélectionnés pour leur capacité d'interaction avec les oxoanions – incluant les phosphodiesters de l'ADN – ont été bisfonctionnalisés pour sonder l'importance des interactions secondaires dans les auto-assemblages petites molécules - ADN. Deux approches différentes, rationnelle et combinatoire dynamique, ont été utilisées pour étudier les interactions au sein des auto-assemblages formés le long du squelette phosphodiester.Avec l'approche rationnelle, des guanidiniums bisfonctionnalisés avec des groupements aromatiques de taille variable ont démontré leur capacité à s'auto-assembler avec l'ADN en solution aqueuse via la reconnaissance du squelette phosphodiester. Les expériences de compétition montrent l'importance des interactions d'empilement π-π dans la stabilisation de ces auto-assemblages.Dans le cadre de l'approche combinatoire dynamique, un guanidinium comportant deux terminaisons aldéhyde a été utilisé pour générer, par amination réductrice, des bibliothèques combinatoires dynamiques basées sur la liaison imine. La génération de bibliothèques avec différentes amines en absence et en présence d'oligo(dT) sur cellulose met en évidence des effets de matrice caractérisés par des changements constitutionnels. Les résultats montrent ainsi que les constituants aux groupements cationiques et aromatiques sont sélectivement retenus contrairement aux constituants portant des substituants anioniques. Les informations structurales obtenues par ces deux approches pourront à l'avenir être utilisées pour la conception de nouveaux ligands de l'ADN.Parallèlement à ces études des interactions petites molécules – ADN, des polymères covalents dynamiques poly-acylhydrazones combinant des moitiés cationiques et de courts groupements d'éthylène glycol au sein de leur chaîne principale ont été conçus. Ces matériaux, capables de s'auto-assembler sous forme d'oligomères par polycondensation à haute concentration, complexent efficacement l'ADN double brin dans les médias biologiques et sont dégradables en milieu acide. L'association de ces deux caractéristiques les rend donc intéressants pour une application en tant que vecteurs « intelligents » pour la délivrance de gènes. / The present research work aims to learn more about the interactions inside small-molecules – DNA self-assemblies in order to facilitate the conception of future DNA ligands or vectors. To achieve this goal, guanidinium compounds, selected for their recognized ability to interact with oxoanions – DNA phosphodiesters – were bisfunctionnalized to probe the importance of secondary interactions in the small-molecules – DNA self-assemblies. Two different approaches, rational and dynamic combinatorial, were used to study the interactions inside the self-assemblies formed along the phosphodiester backbone.With the rational approach, guanidiniums bisfunctionnalized with aromatic groups of varying size demonstrated the ability to self-assemble with DNA in aqueous solution via phosphodiester recognition. The competition experiments show the importance of the π-π stacking interactions in the stabilisation of these self-assemblies.Within the framework of the dynamic combinatorial approach, a guanidinium bearing two aldehyde terminations was used to generate, by reductive amination, dynamic combinatorial libraries based on the imine bond. The generation of libraries with different amines in absence and in presence of oligo(dT) on cellulose shows templating effects that are characterized by constitutional changes. The results thus show that constituents with cationic or aromatic groups are selectively retained on DNA while those featuring anionic groups are not.The structural information gained by these two approaches could be used in the future to design new DNA ligands.In parallel to these studies of the small-molecules – DNA interactions, dynamic covalent polymers combining cationic moieties and short ethylene glycol groups in their principal chain have been designed. These materials are able to self-assemble as oligomeres by polycondensation performed at high concentration and effectively complex double-stranded DNA in biological media and are degradable in acidic conditions. The association of these two characteristics make them interesting for an application as “smart” vectors for gene delivery.

Ce travail de thèse a porté sur l’élaboration de nanomatériaux hybrides de type nano-câbles fonctionnels, composés de polymères covalents et de molécules auto-assemblées. L’approche «bottom-up» adoptée repose sur des processus uniquement physiques, à savoir la nucléation hétérogène, la cristallisation et la gélification thermo réversible. Deux systèmes hybrides ont été élaborés et étudiés: le premier est composé de molécules de tetra-2-éthylhexanoate de bicuivre (CuS8) auto-assemblées en filaments, lesquels sont encapsulés au sein des fibrilles de polystyrène isotactique (iPS). Nous avons montré au travers de différentes études (DSC, DNPA,SQUID, EXAFS et IR-TF) que leur encapsulation permet non seulement de les stabiliser mais également de modifier leur comportement antiferromagnétique. Le deuxième système a consisté à des fibrilles de poly(alkylthiophène)s (P3AT), emmaillotées au moyen de molécules diamides (BHPB-10) capables de s'assembler en nanotubes. En plus des études de la morphologie et de la structuration par TEM et UV-Vis,nous avons étudié les propriétés de conductivité du système hybride P3BT/BHPB-10 en C-AFM. Nous avons montré qu’il est effectivement possible de réaliser des nano-câbles semi-conducteur gainés. / This thesis deals with new hybrid nanomaterials of functional nanocable-like structures, consisting of covalent polymers and self-assembled molecules. The «bottom-up» approach adopted for the elaboration is based only on physical processes such as heterogeneous nucleation, crystallization and thermoreversible gelation. This original approach allowed us to easily prepare two functional nanocables: the first consisted of bicopper tetra-2-ethylhexanoate (CuS8) molecules self-assembled on filaments which are encapsulated within isotactic polystyrene (iPS) fibrils. We proved throughout different studies (DSC, SANS, SQUID, EXAFS and FT-IR) that the encapsulation allows one to get stable filaments, and particularly to modify their antiferromagnetic behavior as well. The second system constituted of poly(alkylthiophene)s fibrilles (P3AT), sheathed by diamides molecules (BHPB-10) self-assembled on nanotubes. Besides the morphological and the structuration studies (TEM and UV-Vis), we investigated the conductivity of the hybrid system P3BT/BHPB-10 by C-AFM. Results showed the possibility to obtain sheathed semi-conducting nano-cables.