From Microscopic to Mesoscopic Descriptions: Coarse-graining of Polymer Melts and their Mixtures M. Guenza, Chemistry Department, University of Oregon Macromolecular liquids are complex fluids, characterized by the presence of several length scales in which relevant phenomena take place. To correctly describe the structure and dynamics of polymer liquids from the short- to the long-range scale, it is necessary to develop techniques to transfer information efficiently from the local to the global scales and vice versa. We proposed a microscopic theory for coarse graining of polymer melts and their mixtures.1,2 The theory has been extended to treat diblock copolymer liquids, where each molecule is mapped into a dumbbells of interacting soft colloidal particles.3 Starting from the Ornstein-Zernike equation, we derived analytical forms of the total correlation functions for block-block, block-monomer, and center-of-mass pairs, as a function of temperature, density, chain length, and chain composition. The theory correctly predicts thermodynamically-driven segregation of diblocks into microdomains as a function of temperature.3 Comparison of the theory with united-atom molecular dynamics simulations, in the athermal regime, shows quantitative agreement (see Figures). 1) E.Sambriski et al. J.Chem.Phys. 125, 234902 (2006) 2) E.Sambriski et al. J.Phys.:Condens.Matt 19, 205115 (2007) 3) E.Sambriski and M.G.Guenza, Phys. Rev. E (in press) Comparison theory vs. simulations of the block-block total correlation functions in real and reciprocal spaces for an asymmetric diblock copolymer f=NA/NB=0.25, AA (), BB (), AB ().