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Although the synthesis of polymers with highly controlled molecular architectures has gained increased importance due to the rising demand for specialty polymers that possess novel properties, their physical characteristics are direct consequences of the size and constitution of the covalent structures of the polymer. Our program aims to prepare and characterize polymers, whose structures and properties are determined by non-covalent interactions. These novel polymer architectures are comprised of macrocycles threaded by linear macromolecules and are called polyrotaxanes. Polyrotaxanes are considered to be physical analogs of block or graft copolymers or molecular interpenetrating systems. The design and synthesis of the macrocyclic component, "blocking groups" to constrain the macrocycles and the polyrotaxane will be described. / Ph. D.

Polyrotaxanes are novel polymer architectures consisting of theo components. One component is the macrocycel consisting of 24-60 atoms; it is threaded by he second component, i.e., the linear backbone polymer. / Ph. D.

The focus of the following research was to use the self-assembly process to create rotaxanes between several large bisphenylene crown ethers (> 22 atoms) with secondary ammonium salts. Also of great interest was to understand the complexation behavior of the crown ethers with the salts, with emphasis on determining the stoichiometries and association constants of the complexations in solution using NMR spectroscopy. The stoichiometry of the complexes was determined by the mole ratio method and the association constants were calculated graphically. Bis-(m-phenylene)-26-crown-8 did not form a complex in solution with several secondary ammonium salts even though the cavity size is large enough to allow the formation of pseudorotaxanes. However, the larger crown ether, bis-(m-phenylene)-32-crown-10 (BMP32C10), did form a complex. The complex stoichiometry varied between 1:1 (crown:salt) in solution and 1:2 in the solid state as evidenced by NMR and X-ray crystallography, respectively. The solid state complexes were pseudorotaxanes. Also, an interesting "exo" complex was formed in the solid state between BMP32C10 and a secondary diammonium salt. The major binding force for the complexes in the X-ray structures was hydrogen bonding. Weaker secondary stabilization was achieved via aryl-aryl aromatic interactions. The difference between the stoichiometries in the two phases and the observance of an "exo" complex demonstrates that one must be careful in describing the complexes in each phase. Also investigated was the complexation formed between dibenzo-24-crown-8 (DB24C8) and secondary diammonium salts. The association constants for the complexes were found to be relatively higher. Due to the weaker association constants and the different stoichiometries of complexation the meta-susbtituted bisphenylene crown ethers were not recommended for the formation of larger complexes, i.e. polyrotaxanes. However, it is suggested that the DB24C8 moiety be used in components of supramolecular assemblies. The functionalization of poly(propylene imine) dendrimers with two different crown ethers as peripheral moieties was attempted. The 1st, 3rd, and 5th generation poly(propylene imine) dendrimers were functionalized with 1,3-phenylene-16-crown-5 moieties by reacting the surface primary amines with the corresponding succinimide ester of the crown ether. The larger DB24C8 succinimide ester was not as reactive and full functionalization was not achieved. / Ph. D.

Dibenzo-30-crown-10 (DB30C10) is one of the first-generation macrocyclic hosts discovered by Pedersen. Crown ethers originally attracted attention due to their ability to encapsulate metal cations and render them soluble in organic solvents. These studies helped to launch host-guest chemistry as a discipline within supramolecular chemistry. Crown ethers form complex molecules containing organic cations and neutral organic molecules. Additionally, they form components in supramolecular architectures such as catenanes, rotaxanes, and supramolecular polymers. They have been used as selective hosts in diverse applications such as wastewater treatment, switchable catalysis, therapeutic agents, sensors, molecular machines, and stimuli responsive materials "smart polymers". Despite the vigorous research activity in the field, DB30C10 has received surprisingly little attention. DB30C10 was reported in 1967 and has been commercially available since 1992; however, it has been mostly overlooked as a host in favour of smaller crown ethers such as DB24C8, B15C5, 18C6 and 15C5. Herein we present an improved synthetic route that improves the yield of the cyclization step in the synthesis of DB30C10 from 25% to 88% enabling us to prepare multiple grams of the material without the use of pseudo high-dilution techniques. The same methodology was applied to three other crown ethers with similar improvement in yield. Four new rotaxanes based on the DB30C10-paraquat binding motif were used to investigate the binding conformation of DB30C10 and paraquat. The new rotaxanes were characterized by 1H, 13C and 2D-NOESY NMR, mp, and HRMS. A single crystal X-ray structure of one of the [2]rotaxanes was obtained. To our knowledge, this is the first crystal structure of a rotaxane based on this particular binding motif. This result illustrated that DB30C10 was a suitable host for the construction of supramolecular systems and polymers. Our eventual goal is to use DB30C10 in the construction of supramolecular polymers with novel topologies. Therefore, the relative threading efficiency of DB30C10 in solution had to be determined. A series of segmented polyurethane poly(pseudorotaxanes) with paraquats in the backbone were synthesized with different crown ether or cyptand hosts. The threading efficiency was determined by 1H NMR. / Ph. D.

Rotaxane chemistry provides a new direction of research in polymer architectures. Unlike conventional polymers, polyrotaxanes are molecular composites comprised of macrocycles threaded by linear polymer backbones with no covalent bonds between the two components. This novel class of materials displays unusual chemical and physical properties due to their unique architectures. The studies include crown ether and blocking group syntheses, synthetic methodologies leading to rotaxanes and polyrotaxanes and structure-property relationships of polyrotaxanes. Crown ethers (30-crown-10, 36-crown-12, 42-crown-14, 48-crown-16 and 60-crown-20) were systematically synthesized from low molecular weight glycols with 30 - 60% yields. Bis(p-phenylene)-32-crown-4 and bis(p-phenylene)-34-crown-10 (BPP34C10) were also synthesized in 8 - 13% yields; the latter was synthesized with four different synthetic routes. All crown ethers were prepared in large quantities. A series of monofunctionalized triaryl derivatives were also synthesized as rotaxane blocking groups. A series of polyrotaxanes comprised of a polyurethane backbone and crown ethers with ring size ranging from 36 - 60 membered were synthesized via the statistical threading method. The polyrotaxane formation was proven by multiple reprecipitations, ¹H-NMR and GPC analyses. The threading efficiency (rings per repeat unit) increases from 0.16 to 0.87 with an increase in ring size of crown ethers from 36 to 60 membered at 1.5 molar ratio of crown ether to linear glycol. Host-guest complexation of paraquat dication and BPP34C10 has been studied. A series of difunctionalized paraquat dication derivatives was synthesized and used to prepare host-guest complexes (pseudorotaxanes) with BPP34C10. X-Ray crystal structures of the complexes were determined. Furthermore, a class of viologen-containing polyurethane elastomeric polyrotaxanes was synthesized via this host guest complexation. The threading efficiencies from this method were quantitative. Through rotaxane formation, polymer solubilities increase and glass transition temperatures decrease. Evidenced by DSC and WAXS analyses, the crown ether forms crystalline domains without dethreading from the amorphous polyurethane backbone. This process is kinetically "retarded". It is time and temperature dependent and reversible. It can only be observed for polyrotaxanes with large rings and high ring contents, which provide high mobilities of rings along the backbone and also wide T_m - T_g windows. The study of recrystallization kinetics has also shown that 60-crown-20 recrystallizes much slower in a polyrotaxane than in its physical blend with the model polymer. / Ph. D.

Les éthers de cellulose (EC) sont des adjuvants couramment introduits dans les mortiers pour améliorer leurs propriétés. Malgré le retard d’hydratation du ciment engendré par ces polysaccharides, ils sont capables d’améliorer la maniabilité et la rétention d’eau des matériaux cimentaires.Cette étude a été initiée afin d’accroître les connaissances sur l’effet des EC sur la rétention d’eau des mortiers à l’état frais. L’objectif est double : identifier les paramètres physico-chimiques jouant un rôle clé et clarifier les mécanismes d’action de dérivés cellulosiques dans les matériaux cimentaires.Pour ce faire, grâce à un large panel d’EC, l’influence des paramètres structuraux des molécules a été élucidée. Les résultats ont démontré que la masse moléculaire était un paramètre primordial alors que les degrés de substitution des groupements greffés sur la molécule ont un impact négligeable sur la rétention d’eau des mortiers. Pour comprendre les mécanismes d’action des EC dans les phénomènes de rétention d’eau, deux pistes ont été explorées. La première a consisté à savoir s’il existait une relation entre le comportement rhéologique des mortiers et leur capacité à retenir l’eau lors d’un contact avec un substrat. L’étude rhéologique a montré que les EC sont des agents viscosants et que pour des EC ayant des degrés de substitution identiques, la viscosité et la rétention d’eau du mortier semblent aller de paire. Cependant, cette relation n’est pas aussi simple. En effet, des propriétés de rétention d’eau différentes ont été mesurées pour des mortiers ayant des consistances voisines. La capacité des mortiers à retenir l’eau ne peut donc pas être déterminée uniquement à partir de son comportement rhéologique. Par ailleurs, d’autres molécules telles que les dérivés de l’amidon, ont mis en évidence une évolution opposée de la rétention d’eau avec les propriétés rhéologiques. Ainsi, la consistance d’un mortier ne peut pas à elle seule expliquer les phénomènes de rétention d’eau des mortiers adjuvantés avec les éthers de cellulose.La seconde hypothèse souvent avancée pour expliquer les propriétés de rétention d’eau est que les dérivés cellulosiques forment une barrière de diffusion à l’eau dans le mortier. La capacité des polymères à former des films a été étudiée à l’aide de deux techniques de résonance magnétique nucléaire (RMN) : la RMN à gradients de champ et la relaxométrie RMN. A l’aide de ces deux techniques, il a été montré que les EC n’ont aucun effet sur le coefficient de diffusion de l’eau dans le volume et à la surface des solides. Une étude temporelle menée par relaxométrie a mis en avant l’importance de la quantité d’eau piégée transitoirement à la surface des solides. / Cellulose ethers (CE) are commonly used as additives to improve the quality of cement-based materials. As admixtures, they improve the properties of mortars such as workability, open time and water retention. This study is devoted to improve the knowledge on the influence of cellulose ethers on the freshly-mixed mortars water retention. The aims of this thesis are to identify they key structural parameters of the CE which influence the water retention and to clarify the water retention mechanisms of CE in freshly mixed mortars.In this frame, the influence of cellulose ethers molecular parameters was explored. The results demonstrated that molecular weight is the key parameter concerning the water retention capacity of mortars. On the contrary, the substitution degrees seem to have a lower impact on this property. To understand water retention mechanisms, two ways were investigated. The first hypothesis is that there is a relationship between the rheological behavior of mortars and their ability to retain water upon contact with a substrate. The rheological study showed that CE are viscosity modifiers. Moreover, for CE with the same substitution parameters, mortar’s viscosity and its water retention seem to go hand in hand. However, this relationship is not so simple. Indeed, the water retention properties were measured for different mortars with close consistencies. This comparison demonstrated that the ability of mortars to retain water cannot be determined from its rheological behavior. In addition, other molecules such as starch derivatives, showed an opposite trend: the higher the consistency, the lower the water retention. Thus, mortar’s consistency is not the only parameter which can explain water retention capacities of CE-admixed mortars.The second hypothesis proposed to explain water retention properties is that cellulose derivatives form a diffusion barrier to water into the fresh mortar, because CE used to form film. The ability of polymers to reduce water mobility was investigated using two techniques of nuclear magnetic resonance (NMR): NMR field gradient and relaxometry NMR. Using these two techniques, it was shown that the EC have no effect on the diffusion coefficient of water in the volume and surface of solids. A study conducted by relaxometry NMR highlighted the importance of the amount of water trapped temporarily at the surface of solids.