UVM Theses and Dissertations
Format:
Print
Author:
Richardson, Adam David
Dept./Program:
Chemistry
Year:
2012
Degree:
PhD
Abstract:
This dissertation will describe the synthesis and mechanical behavior of polymer networks utilizing either a covalent or non-covalent crosslinking mechanism. Two chemically different covalent networks containing nanoparticles, surface fiinctionalized by grafting-to synthetic approaches, are investigated. A hydrogen-bonding network motif is also presented for the creation of a series of polymer-based organogels.
Epoxy-based thermosets are currently at the forefront of high performance materials being used in the naval and aerospace industries. Iricorporation of nano-scale fillers such as inorganic particles or nanotubes have the potential to augment the mechanical properties of epoxy systems but full realization has been hampered by their poor dispersion characteristics. The first research topic discussed herein is of a new strategy to produce epoxy-based nanocomposites using silica nanoparticles functionalized with varying molecular weights of a compatible polymer. Particle characterization confirms a correlation between the grafting polymer feed-ratio and the polymer layer thickness. Dispersion was significantly influenced by the tethering of polymer to the surface of nanoparticles.
The development of new energy-damping materials in areas such as sports and military applications are of increasing concern as medical research suggests that current protective technology in these fields is insufficient to prevent long-term adverse health effects. The second research topic describes a novel class of materials that has been found to possess superior damping properties, and the synthetic strategy utilized improves the dispersion of silica nanoparticles into the matrix using reactive tethers. The length of the nanoparticle tethers was varied, as were the feed-ratios, which resulted in significant effects on the mechanical properties of the nanocomposites. Dispersal of nanoparticles in the matrix was not strongly dependent on the tether size or functionality.
Networked materials containing hydrogen-bond crosslinks represent a robust and reversible technique in the design of gels for use in areas ranging from energy storage devices to cosmetics. While a multitude of examples of these types of gels that utilize water as a solvent already exist, few are useable with organic solvents. The third project presented herein examines the preparation and characterization of a novel series of organic solvent gelators created from commercially available polymers. Stable gels were formed in a remarkably wide range of solvent polarities and temperatures. The techniques used in the gelator synthesis make this a commercially relevant process that is easily applicable to variety of other polymers.
Epoxy-based thermosets are currently at the forefront of high performance materials being used in the naval and aerospace industries. Iricorporation of nano-scale fillers such as inorganic particles or nanotubes have the potential to augment the mechanical properties of epoxy systems but full realization has been hampered by their poor dispersion characteristics. The first research topic discussed herein is of a new strategy to produce epoxy-based nanocomposites using silica nanoparticles functionalized with varying molecular weights of a compatible polymer. Particle characterization confirms a correlation between the grafting polymer feed-ratio and the polymer layer thickness. Dispersion was significantly influenced by the tethering of polymer to the surface of nanoparticles.
The development of new energy-damping materials in areas such as sports and military applications are of increasing concern as medical research suggests that current protective technology in these fields is insufficient to prevent long-term adverse health effects. The second research topic describes a novel class of materials that has been found to possess superior damping properties, and the synthetic strategy utilized improves the dispersion of silica nanoparticles into the matrix using reactive tethers. The length of the nanoparticle tethers was varied, as were the feed-ratios, which resulted in significant effects on the mechanical properties of the nanocomposites. Dispersal of nanoparticles in the matrix was not strongly dependent on the tether size or functionality.
Networked materials containing hydrogen-bond crosslinks represent a robust and reversible technique in the design of gels for use in areas ranging from energy storage devices to cosmetics. While a multitude of examples of these types of gels that utilize water as a solvent already exist, few are useable with organic solvents. The third project presented herein examines the preparation and characterization of a novel series of organic solvent gelators created from commercially available polymers. Stable gels were formed in a remarkably wide range of solvent polarities and temperatures. The techniques used in the gelator synthesis make this a commercially relevant process that is easily applicable to variety of other polymers.