Experimental and theoretical research is being conducted on a wide range of problems on condensed phase dynamics of small molecules, macromolecules and particles of both materials and biological interest. Work includes development of experimental techniques, thorough experiments on specific systems, and theoretical modeling and computer simulation. Our current work may be conveniently divided into two broad areas:

Structure and Dynamics of Semi-rigid, Rigid and Liquid Crystalline Polymers: Many macromolecules and particles of materials or biological importance may be modeled as rigid or semi-rigid rods. Our objective in this area is to provide an in-depth understanding of the translational, rotational, and flexing dynamics of such materials in liquid dispersions. Our work includes studies of local and overall dynamics of rodlike molecules. For example, oligonucleotides and helical polypeptides of varying lengths are being extensively investigated.

The motions of molecules in solutions in which they interact strongly is of great interest in polymer science since most molecules are processed under these conditions. For neutral polymers these interactions occur in the semidilute and concentrated regions. For polyelectrolytes, molecules may interact strongly in low ionic strength solutions at relatively low concentrations because of unshielded electrostatic interactions. Both neutral and charged systems are being studied by theoretical and experimental techniques, including dynamic light scattering, small angle neutron scattering, transient electric birefringence decay and x-ray photon correlation spectroscopy.

Composite Liquids: Composite liquids are a ubiquitous class of materials which contain polymers, particles and solvent. They are used, among other things, as ceramic precursors, lubricants, paints and coatings, adhesives and in chromatographic columns. They are also important constituents of biological systems (e.g., protoplasm, blood). Due to their complexity and the lack of adequate model systems, the interactions between the species in such systems are not well understood. Rod-coil liquids are liquids composed of a rod polymer, a coil polymer and a solvent. We are currently constructing model rod-sphere composite liquids, and model rod/coil/solvent systems which can be studied by scattering techniques.

1) "Diffusion and Microstructural Properties of Dispersions of Charged Nano-sized Proteins: Experiment vs. Theory," J. Gapinski, A. Wilk, A. Patkowski, W. Haeußler, A.J. Banchio, R. Pecora, and G. Naegele, J. Chem. Phys. 123, 54708 (2005).

2) "Self-diffusion in Solutions of a 20 base pair Oligonucleotide: Effects of Concentration and Ionic Strength," A. Wilk, J. Gapinski, A. Patkowski, and R. Pecora, J. Chem. Phys. 121, 10794 (2004).

3) "Translational and Rotational Dynamics of Rodlike Cellulose Whiskers," with M. M. De Souza Lima, J. Wong, M. Paillet, R. Borsali, and R. Pecora, Langmuir 19, 24 (2003).

4) "Dynamics in Rod/Sphere Composite Liquids" in Dynamics of Colloid and Polymer Systems, R. Borsali and R. Pecora, Eds., Kluwer, Dordrecht, Netherlands, 2002.

5) "Dynamic Light Scattering and Small Angle Neutron Scattering Studies of Ternary Rod/Coil/Solvent Systems," E.T. Hanson, R. Borsali, and R. Pecora, Macromolecules 34, 2208 (2001).