We examine problems associated with the structure, phase behavior and dynamics of bulk and thin film polymer and polymer-based nanocomposite systems.
Thin Films: A diverse range of applications, from organic electronic devices and sensors to coatings and patterning, rely on the properties and performance of polymers under various conditions of confinement, particularly thin film geometries. The size-scales of confinement may be comparable to nanometers or tens of nanometers, depending on the application. However, the influence of interactions between polymer chains and the interfaces (free surface or substrate) may be manifested at length scales far beyond the size of the chain and often have a profound influence on the properties of the polymer. To this end, our program on polymer thin films comprise problems in three general categories: (1) wetting, interfacial instabilities and pattern formation, and self-assembly; (2) the influence of confinement and interfacial interactions on the glass transition, diffusion and viscosity, as well as on the phase and ordering transition temperatures of polymer mixtures and block copolymers, respectively; (3) the organization of nanoparticles (C60 fullerenes, nanotubes, semiconductor and metallic nanopaticles) in thin films. Our goal is to develop new rules to design and to “tailor” properties of thin films for various applications.Bulk: The second aspect of our research encompasses bulk rheological and dynamic mechanical behavior of polymer-based nanocomposite (organoclays, metal oxides, nanotubes ec.) systems. We are interested in developing an understanding of the connection between the nano-scale organization, meso-scale structure and bulk properties in these systems.
Our program is interdisciplinary, cross-cutting different fields, from physical chemistry of surfaces, to the processing of polymers, to the physics of materials. We employ a range of experimental tools, including scanning force microscopy, transmission electron microscopy, neutron scattering, ellipsometry, DMA and rheology, and our group collaborates with a number of theoretical groups here and elsewhere.