Structural Investigations of Polymeric Nanomaterials

摘要

Nanomaterials whose structure and properties can be rationally controlled have numerous applications for devices. Two approaches to control nanomaterial structures and properties were taken in this research. The first approach was characterization of nanocomposite thin films composed of polymers and nanoparticles by X-ray and neutron techniques and the second approach was synthesis and characterization of peptide-dendron hybrids that self-organize into periodically ordered arrays of nanostructures.;In the first approach, strategies were investigated for controlling and understanding the properties of nanocomposite thin films. The ability to selectively use nanoparticles to stabilize polymer thin films is useful for technical applications such as adhesives, lubricants, and coatings. By using X-ray and neutron techniques to characterize a nanocomposite thin film, we found that the addition of nanoparticles can allow the chain conformation of substrate-adsorbed chains to become expanded in the direction normal to the film surface. This results in adsorbed polymer chains acting as "connectors" between the substrate surface and free chains and hence stabilizing the thin film.;In the second approach, highly branched macromolecules known as dendrons were used to synthesize self-organizing peptide-dendron hybrids. The peptide coiled coil structure can thus be preserved in a hybrid biomaterial. The peptide-dendron hybrids form hexagonal columnar liquid crystals. These hybrids form bundles of alpha-helices whose structure and stoichiometry may be programmed by the sequence of the peptide. This work allows for investigation into how the sequence of the peptide can be used to control the properties of the peptide-dendron hybrids.