This proposal, "US-Bulgaria Cooperative Research on Computer Simulations of Polydisperse Polymer Systems," will be carried out by Dr. David P. Landau, University of Georgia and Dr. Andrey I. Milchev, University of Sofia. It envisages an ambitious program of research, designed to shed light on the complex cooperative behavior of a polydisperse system of semiflexible polymer chains in the presence of an adsorbing surface. Since the thermodynamic properties of such a system are so far largely unknown, the researchers believe that in a collaboration of three years they can produce a sufficient number of results in order to get a complete picture of the phenomena in question. The program of research should focus on: (1) Determination of the order of the disorientation phase transition in 2D; (2) Establishment of a total phase diagram in the multiparameter space of the energy interactions, temperature and density; (3) Investigation of adsorption isotherms and the adsorption-description phase transition for polydisperse systems with different average chain length and stiffness; (4) Study of the density profile and the structure of the polymer solution as a function of the distance from the adsorbing surface; (5) Investigation of the impact of impurities on the thermodynamic and structural properties of the system. The problem is of major practical importance since it has broad implications in lubrication, adhesion, surface protection, etc. technology. Polymers, adsorbed at the surface of colloid particles, lead to (steric) stabilization of the colloid suspension which is important for dyes production. This research in materials theory fulfills the program objective of advancing science by enabling leading experts in the United States and Bulgaria to combine complementary talents and pool research resources in areas of strong mutual interest and competence.
