This Presidential Young Investigator research program will be developed along three lines: investigation of the thermodynamics of polymer mixing, evaluation of the dynamics of polymer-polymer phase separation and block copolymer ordering, and establishment of a synthesis and characterization facility for the development of model materials. In the area of thermodynamics two classes of mixtures are of principal interest: binary polymer mixtures and block copolymers. Research efforts will be directed at advancing our understanding of polymer segment interactions using model systems, and at correlating this knowledge with experimentally determined excess thermodynamics properties, phase diagrams, and interfacial phenomena. Such information will be obtained using neutron, x-ray and light scattering methods, along with electron and optical microscopy techniques. Two projects will be initiated in the dynamics category: spinodal decomposition, and nucleation and growth of binary polymer mixtures, and rheological characterization of order and disorder in block copolymers. These investigations take advantage of our thermodynamic results in developing the appropriate phase diagrams with which to explore issues relating to the dynamics of phase separation, and the properties of the resulting materials. Isotopic polymer mixtures represent one example of an ideal model system which we will be using in study -ing spinodal decomposition by light and neutron scattering. Investigation of block copolymers dynamics will rely mainly on the combined use of a mechanical spectrometer and small-angle x- ray and neutron scattering. Achieving these thermodynamics and dynamics goals depend upon the ability to manipulate the molecular weight, microstructure, isotopic constitution, and chain architecture of model polymers. This requirement will be met through the development of an anionic polymerization facility, augmented by a catalytic hydrogenation and molecular characterization capability. Thus, information regarding polymer thermodynamics and dynamics can be applied directly to materials optimization.
