Ring-opening metathesis polymerization (ROMP) is a great tool for synthesizing polyolefin materials with different topologies, including hyperbranched polymers—polymers with high degrees of branching and many end groups. However, hyperbranched polymer synthesis via ROMP is challenging due to multifunctional-monomer or multi-polymerization requirements. To simplify the synthesis of hyperbranched ROMP polymers, we developed a new synthetic approach: Self-condensing ROMP. The self-condensing ROMP approach involves a ROMP initiator modification to attach a ROMP-polymerizable group (a ROMP monomer), producing a ROMP "inimer" (initiator + monomer). The ROMP inimer initiates the polymerization and becomes a branching unit in the polymer structure, resulting in single-step hyperbranched polymer synthesis. The key challenge is controlling of this approach the ROMP initiator reactivity to avoid initiating polymerization during the ROMP inimer synthesis. Well-defined ruthenium-based olefin metathesis catalysts are common ROMP initiators due to their high stability, reactivity, and functional group tolerance. Thus, we studied the olefin metathesis catalyst activation temperature to enable ROMP initiator-monomer coupling. Based on the catalyst activity, we designed and synthesized a series of ROMP inimers. Then, we synthesized hyperbranched polymers via self-condensing ROMP. The characterization of hyperbranched polymers indicated the effect of branching density on the physical properties of the polymer. This approach introduced a new class of olefin metathesis complexes, ROMP inimers, containing both the initiator and propagating center. This approach provides a way to synthesize hyperbranched polymers from any known ROMP monomers in a single step. This dissertation also includes the synthesis and characterization of a bimetallic Ru complex that could directly synthesize cyclic polyolefin. We also include the synthesis and characterization of copper-ruthenium bimetallic olefin metathesis catalysts. / Doctor of Philosophy / Hyperbranched polymers are a class of polymers having highly branching structures and functional end-groups, and presenting distinct physical and chemical properties compared with linear polymers. Hyperbranched polymers have been used for many applications including processing additives, cross-linkers, compatibilizers, and catalyst supports. Well-defined ruthenium-based olefin metathesis catalysts enable the synthesis of materials with different topologies, functionalities, and chemical and physical properties via ring-opining metathesis polymerization (ROMP). Ligand modifications on ruthenium catalysts have been applied to improve the catalyst stability and reactivity. However, this dissertation modifies olefin metathesis catalysts to synthesize hyperbranched polymers in a single step. This dissertation illustrates catalyst functionalization with a ROMP monomer moiety to synthesize a ROMP inimer (inimer= initiator + monomer). The ROMP initiator—olefin metathesis catalyst—and ROMP monomer coupling produces an "inimer". The inimer can undergo self-condensing ROMP with a ROMP monomer addition to synthesize hyperbranched polymers. This approach introduced a new class of olefin metathesis complexes containing both the initiator and propagating center. This approach also provides a way to synthesize hyperbranched polymers from any known ROMP monomers in a single step.

The utilization of renewable sources as alternatives for petroleum and natural gas products has immense commercial, health and global warming significance. D-Isosorbide (2) is a bifunctional, polar, chiral and rigid molecule, which is produced from renewable sources. Synthesis of new polymers containing 2 is of interest for polymers and in drug delivery. The aim of the present work is to synthesize various polymers (homo- and copolymers) containing 2 via the olefin metathesis routes, ring-opening metathesis polymerization (ROMP) and acyclic-diene metathesis polymerization (ADMET). N-Phenyl-7-oxanorbornene-dicarboximide, and norbornene functionalized onto 2 were used as the monomers for ROMP. These monomers were polymerized using Grubbs’ catalysts to generate a series of homo-, co-, block and cross-linked-polymers. These polymers were characterized using GPC, NMR, and IR. In addition, ADMET polymerization of a terminal diolefinunctionalized D-isosorbide (2) was also conducted to produce ADMET polymers.

No description available.

Externally initiated o-tolyl initiated poly(3-hexylthiophene) (P3HT) was synthesized according to Grignard metathesis polymerization at varying chain length to compare number average molecular weights (Mn) obtained by gel permeation chromatography (GPC) and 1H NMR end group analysis. The extent of overestimation by GPC (1.3) was determined to be lower than previously reported for low Mn polymers. However, an apparent GPC quantification limit was observed as NMR Mn correlated well to predicted results. Static light scattering studies on high Mn polymers provided evidence that the true molecular weight was more similar to GPC-derived Mn. Despite nearly 100% external initiation efficiency, at a certain Mn limit new uninitiated chains may be synthesized. It is suggested that the synthesis of externally initiated P3HT should be limited to Mn below 40 kDa to ensure fully externally initiated chains. A proposal for the synthesis of externally initiated macrocyclic P3HT will also be discussed.

Block copolymer self-assembly has demonstrated sub-optical lithographic resolution . High values of chi, the block copolymer interaction parameter, are required to achieve next-generation lithographic resolution . Unfortunately, high values of chi can lead to thin film orientation control difficulties , which are believed to be caused by large differences in the surface energy of each block relative to the substrate and the free surface. The substrate-block interface can be modified to achieve a surface energy intermediate to that of each individual block ; the air-polymer interface, however, presents additional complications. This thesis describes the synthesis of polymers for top coat surface treatments, which are designed to modify the surface energy of the air-block copolymer interface and enable block copolymer orientation control upon thermal annealing. Polymers with β-keto acid functionality were synthesized to allow polarity switching upon decarboxylation. Syntheses of anhydride containing polymers were established that provide another class of polarity switching materials. / text

Externally initiated o-tolyl initiated poly(3-hexylthiophene) (P3HT) was synthesized according to Grignard metathesis polymerization at varying chain length to compare number average molecular weights (Mn) obtained by gel permeation chromatography (GPC) and 1H NMR end group analysis. The extent of overestimation by GPC (1.3) was determined to be lower than previously reported for low Mn polymers. However, an apparent GPC quantification limit was observed as NMR Mn correlated well to predicted results. Static light scattering studies on high Mn polymers provided evidence that the true molecular weight was more similar to GPC-derived Mn. Despite nearly 100% external initiation efficiency, at a certain Mn limit new uninitiated chains may be synthesized. It is suggested that the synthesis of externally initiated P3HT should be limited to Mn below 40 kDa to ensure fully externally initiated chains. A proposal for the synthesis of externally initiated macrocyclic P3HT will also be discussed.

No description available.

This thesis describes the synthesis and application of a new series of amphiphilic graft copolymers with a hydrophobic polyolefin backbone and pendent hydrophilic poly(ethylene glycol) (PEG) grafts. These copolymers are synthesized by ruthenium benzylidene-catalyzed ring-opening metathesis polymerization (ROMP) of PEG-functionalized cyclic olefin macromonomers to afford polycyclooctene- graft -PEG (PCOE- g -PEG) copolymers with a number of tunable features, such as PEG graft density and length, crystallinity, and amphiphilicity. Macromonomers of this type were prepared first by coupling chemistry using commercially available PEG monomethyl ether derivatives and a carboxylic acid-functionalized cycloctene. In a second approach, macromonomers possessing a variety of PEG lengths were prepared by anionic polymerization of ethylene oxide initiated by cyclooctene alkoxide. This methodology affords a number of benefits compared to coupling chemistry including an expanded PEG molecular weight range, improved hydrolytic stability of the PEG-polycyclooctene linkage, and a reactive hydroxyl end-group functionality for optional attachment of biomolecules and probes. The amphiphilic nature of these graft copolymers was exploited in oil-water interfacial assembly, and the unsaturation present in the polycyclooctene backbone was utilized in covalent cross-linking reactions to afford hollow polymer capsules. In one approach, a bis -cyclooctene PEG derivative was synthesized and co-assembled with PCOE-g-PEG at the oil-water interface. Upon addition of a ruthenium benzylidene catalyst, a cross-linked polymer shell is formed through ring-opening cross-metathesis between the bis -cyclooctene cross-linker and the residual olefins in the graft copolymer. By incorporating a fluorescent-labeled cyclooctene into the graft copolymer, both oil-water interfacial segregation and effective cross-linking were confirmed using confocal laser scanning microscopy (CLSM). In a second approach, reactive functionality capable of chemical cross-linking was incorporated directly into the polymer backbone by synthesis and copolymerization of phenyl azide and acyl hydrazine-functional cyclooctene derivatives. Upon assembly, these reactive polymers were cross-linked by photolysis (in the phenyl azide case) or by addition of glutaraldehyde (in the acyl hydrazine case) to form mechanically robust polymer capsules with tunable degradability ( i.e. non-degradable or pH-dependent degradability). This process permits the preparation of both oil-in-water and water-in-oil capsules, thus enabling the encapsulation of hydrophobic or hydrophilic reagents in the capsule core. Furthermore, the assemblies can be sized from tens of microns to the 150 nm - 1 µm size range by either membrane extrusion or ultrasonication techniques. These novel capsules may be well-suited for a number of controlled release applications, where the transport of encapsulated compounds can be regulated by factors such as cross-link density, hydrolytic stability, and environmental triggers such as changes in pH.

Utilizing the diverse functionality of amino acids, a new class of amphiphilic graft copolymers has been synthesized, characterized, and explored for applications in biomaterials and nucleic acid delivery. This thesis research focused on the syntheses of oligopeptide-functionalized polyesters and polyolefins. Polyester functionalization was geared towards applications in biomaterials, tissue engineering, and drug delivery by incorporating sequences that promote cell-adhesion. These polyester- graft -oligopeptide materials were prepared by a 1,3-Huisgen cycloaddition reaction, "click" chemistry, of an azide-terminated oligopeptide (prepared by Fmoc-based solid phase peptide synthesis (SPPS)) and alkyne-containing polyester (synthesized by ring-opening polymerization). Following the syntheses of these materials, they were analyzed by nuclear magnetic resonance (NMR) and organic gel permeation chromatography (GPC). The oligopeptide-functionalized polyolefins were designed for nucleic acid complexation, and therefore the oligopeptide sequences were intended to incorporate positively-charged moieties ( e.g. , oligolysine) for DNA and short interfering RNA (siRNA) complexation. These graft copolymers, prepared by SPPS followed by ring-opening metathesis polymerization, have highly tunable structures that enable control over charge density and polymer backbone rigidity. Moreover, non-ionic hydrophilic grafts such as polyethylene glycol were integrated into these polyelectrolytes such that the charges along the polymer backbone are spaced accordingly while maintaining the hydrophilicity of the polymer. While numerous applications for such charged, "bio-tailored" materials can be envisioned, this work is geared towards positively-charged polyelectrolytes for their potential application in nucleic acid therapy, specifically the delivery of plasmid DNA and siRNA. These graft copolymers were characterized ( 1 H, 13 C NMR, organic and aqueous GPC), studied for their solution properties (static and dynamic light scattering), and investigated as polyplexes with plasmid DNA.

Les acides biliaires sont des composés naturels existants dans le corps humain. Leur biocompatibilité, leur caractère amphiphile et la rigidité de leur noyau stéroïdien, ainsi que l’excellent contrôle de leurs modifications chimiques, en font de remarquables candidats pour la préparation de matériaux biodégradables pour le relargage de médicaments et l'ingénierie tissulaire. Nous avons préparé une variété de polymères à base d’acides biliaires ayant de hautes masses molaires. Des monomères macrocycliques ont été synthétisés à partir de diènes composés de chaînes alkyles flexibles attachées à un noyau d'acide biliaire via des liens esters ou amides. Ces synthèses ont été réalisées par la fermeture de cycle par métathèse, utilisant le catalyseur de Grubbs de première génération. Les macrocycles obtenus ont ensuite été polymérisés par ouverture de cycle, entropiquement induite le catalyseur de Grubbs de seconde génération. Des copolymères ont également été préparés à partir de monolactones d'acide ricinoléique et de monomères cycliques de triester d’acide cholique via la même méthode. Les propriétés thermiques et mécaniques et la dégradabilité de ces polymères ont été étudiées. Elles peuvent être modulées en modifiant les différents groupes fonctionnels décorant l’acide biliaire et en ayant recours à la copolymérisation. La variation des caractéristiques physiques de ces polymères biocompatibles permet de moduler d’autres propriétés utiles, tel que l’effet de mémoire de forme qui est important pour des applications biomédicales. / Bile acids are natural compounds in the body. Their biocompatibility, facial amphiphilicity, rigidity of steroid nucleus, and ease of chemical modification make them excellent candidates as building blocks for making biodegradable materials used in drug delivery and tissue engineering applications. We have prepared main-chain bile acid-based polymers having high molecular weights. Macrocyclic monomers were synthesized from dienes, which consist of flexible alkyl chains attached to a bile acid core through either ester or amide linkages, via ring closing metathesis using first-generation Grubbs catalyst. They were polymerized using entropy-driven ring-opening metathesis polymerization using second-generation Grubbs catalyst. Copolymers were also prepared from monolactone of ricinoleic acid and cholic acid-based cyclic triester monomer via the same method. The thermal and mechanical properties and degradation behaviours of these polymers have been investigated. The properties can be tuned by varying the chemical linking with the bile acid moiety and by varying the chemical composition of the polymers such as copolymerization with ricinoleic acid lactones. The tunability of the physical properties of these biocompatible polymers gives access to a range of interesting attributes. For example, shape memory properties have been observed in some samples. This may prove useful in the design of materials for biomedical applications.