Continued progress in macromolecular science requires a fundamental understanding of miscible blends to make a connection between microscopic structure and end-use properties. As the interdisciplinary research of "soft matter" grows, the need for more rigorous experimental techniques that provides component-specific information in homogenous and heterogeneous amorphous systems is apparent.
The chain-specific information gained through this experimental approach, based on solid-state CODEX NMR experiments, reveals that the effective glass transition for each component in a homogeneous miscible blend may not occur at a common temperature. The slow chain dynamics associated with conformational changes at the chain level have unique central correlation times and correlation time distributions. Quantitative analysis of the CODEX data using the methods developed in this study produce results that are in good agreement with those produced by other documented methods. The temperature dependent models show a clear sensitivity to the changes that occur upon blend formation when compared to the pure components. Entropy increases that occur upon mixing are detected using the CODEX experimental data. The unique advantage to this approach is that such quantitative data can be obtained without isotopic labeling, electric dipole moment constraints, or introduction of probe molecules. This demonstrates the particular capabilities of the experimental strategy that applies to a wide range of more complex macromolecular systems including polymer nanocomposites, organic/inorganic hybrid materials, biological macromolecules, and block copolymers.
|Advisor:||White, Jeffery L.|
|Commitee:||Ausman, Kevin, Blum, Frank, Materer, Nick, Quan, Tracy|
|School:||Oklahoma State University|
|School Location:||United States -- Oklahoma|
|Source:||DAI-B 74/06(E), Dissertation Abstracts International|
|Subjects:||Physical chemistry, Polymer chemistry|
|Keywords:||Amorphous polymers, Correlation times, Dynamic heterogeniety, Friction coefficients, Glass transition, Miscible blends|
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