| Polymer nanocomposites (PNCs) are materials composed of a polymeric host in which particles of nanoscale dimensions e.g. buckyballs, nanotubes, semiconductor of metallic nanocrystals, and clays are incorporated. PNCs, often termed organic-inorganic hybrids, are materials of rapidly growing interest to polymer scientists and engineers as they have properties of both the inorganic and organic components. PNCs are currently being used in a number of fields and new applications are continuously being developed including thin-film capacitors for computer chips, solid polymer electrolytes for batteries, biomaterials for bone cements and a variety of devices in solar and fuel cells.;For the methodology of growing polymers from inorganic surfaces, the inorganic oxide, titania, TiO2 was focused on. As TiO2 has an ability to coordinate with a carboxylic group, in this research RAFT agents having an available carboxyl group were chosen to anchor onto TiO 2 nanoparticles and then grow chains of PAA, PMMA, and PMMA-b-PAA from these modified surfaces. The functionalization of n-TiO2 was determined by FTIR, XPS, and partitioning studies, the livingness of the polymerization was verified using GPC and NMR, while the dispersion of the inorganic filler in the polymer was studied using electron microscopy and thermal analysis.;Methyl methacrylate was selected as the investigated monomer for the kinetic study of polymerization reactions, both in solution and in heterogeneous media. In-situ ATR-FTIR was employed to monitor the conversion of the monomer vs. time during polymerization. The monomer conversion and molecular weight kinetics were explored for the living RAFT polymerization, both in solution and grafted from n-TiO2, with first-order kinetics being observed. It was found that increased graft density on n-TiO2 led to a lower rate of polymerization, attributed to high localized concentration of RAFT agent.;The potential of supercritical carbon dioxide (scCO2) as a green solvent was further examined to synthesize n-TiO2/PMMA via the RAFT process and the rate of polymerization at different pressures and also in the organic solvent THF were compared. The rate of reaction in scCO 2 was found higher than that in the organic solvents.;Due to their small dimensions, nanoparticles tend to strongly agglomerate, hindering the physical and mechanical properties of the nanocomposite materials. In order to circumvent the inherent limitations associated with the agglomeration of nanoparticles in solution, the ultimate goal of this thesis is to develop an approach for growing polymer chains from the surfaces of inorganic oxides. In order to grow polymer chains, the living radical polymerization methodology, reversible addition fragmentation chain-transfer1 was investigated. The kinetics of polymerization reactions, both in solution and in heterogeneous media was investigated. By synthesizing PNCs in organic solvents and in the green solvent, supercritical carbon dioxide (scCO2), the kinetics were tested in various media. In addition, this thesis examined preparing new materials using the reversible addition fragmentation chain-transfer (RAFT) process, such as amphiphilic diblock copolymers used as templates to prepare mesoporous TiO2.;Amphiphilic brush copolymers of PMMA-b-PAA were produced and used as a template to prepare mesoporous TiO2. By using different chain lengths of the PAA block, the morphology of the resulting TiO2 was investigated. These amphiphilic copolymer brushes were also grafted from n-TiO2 to form NiO/TiO2 particles; which can be used as nanocatalysts.;Key Words: nanocomposites, RAFT polymerization, TiO 2, grafting from, poly acrylic acid, poly methyl methacrylate, kinetics, rate of reaction, supercritical CO2, amphiphilic copolymers, mesoporous TiO2. |
