Macromolecular Fluids: Theory, Simulation and Experiment

Florida State University, Tallahassee FL

Investigators

Abstract

New classes of materials are processed as liquid mixtures of "designer" macromolecules either in viscous solvents or in flexible polymer solutions. These macromolecules range from small molecular weight, rod-like liquid crystals to nano-clay platelets, targeting a diverse family of high-performance materials and devices. The molecules are well approximated as ellipsoids, precisely falling within the class of macromolecular fluids accessible by emerging theory, computation, and experiment. Furthermore, rigid-unit, monodisperse molecules suspended in viscous solvent are fundamental model systems. Mathematically, they represent the leading edge of theory; physically, they are the foundation from which many micro-fluidic systems can now be ideally modeled, and eventually understood. Conductivity or barrier properties, while governing material end-use, are passive during processing. Rather, the fundamental issue for design and control is the emergence of structures during processing at length scales (up to microns) far removed from individual molecules, called mesostructures, which empirically dominate ultimate performance features. Examples include sequestered island arrays of liquid crystals and distinguished patterns that arise in rod-like and disc-like nano-composites. The onset, development, and saturation of mesostructures in prototypical flows of rigid-unit macromolecular fluids is the primary focus of the workl. The work identifies open mathematical, numerical, and experimental issues, and constructs collective strategies toward their resolution, combining experimental, theoretical and computational expertise. New class of materials are processed as liquid mixtures of "designer macromolecules" either in viscous solvents or in polymer melts and solutions, in which the designer macromolecules are of simple geometry in a few to several hundred nanometers (1 nanometer is equal to 1 billionth of 1 meter). The material properties are dominated by the emergence of the mesostructure at the micron level (1 micron is 1 millionth of 1 meter) during the material processing. The PI, teamed up with a group of leading experimentalists in the field of complex fluids, identifies the open mathematical, numerical and experimental issues and constructs collective strategies toward their resolution combining experimental, theoretical and computational expertise.