Mechanical Control of Polymer Morphology and Properties: Theory and Simulation

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9709101 Balazs This is a theoretical research grant to study the effects of applied forces on polymer films and blends in order to fabricate tailored interfaces and high-strength materials. To do this, theoretical models and computer simulations will be developed to incorporate external forces; determine how these forces affect morphology; and, to correlate morphology to macroscopic properties. In the study of polymer films, the focus will be on polymer chains tethered to solid surfaces. The interactions between such polymer-coated surfaces are responsible for stabilizing colloidal solutions and reducing friction between interfaces. To model this problem of mechanically compressing, stretching or deforming confined polymer layers, two-dimensional self-consistent field calculations and scaling theory will be used. The results will provide guidelines for fabricating optical devices, such as bistable switches, flocculating agents, which are important in the production of wood and paper products, and layered composites with tailored properties. In the study of polymer blends, the focus will be on the mixing of "off-the-shelf" polymers. This process holds considerable promise as a means of creating new materials at relatively low cost. The actual fabrication of polymer blends, however, poses significant challenges. Most polymers are immiscible and phase separate into macroscopic domains. Shear and flow can produce finer dispersements which improve mechanical properties. %%% This research grant will use theoretical models and computer simulations to study the impact of various forces on the properties of polymers. In particular, the research will study polymer films, such as are used for coatings, and polymer blends (mixed polymers). These studies are at the forefront of research in polymer science and engineering, Besides being of great fundamental interest, and a significant theoretical challenge, the research has the potential to directly affect th e design and production of new materials. ***