Computer Simulations of the Thermodynamic and Phase Diagrams of Polymeric Systems

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9311915 Kumar The primary focus of this research is to understand the practically important question of the miscibility of polymeric systems from a molecular view point. An argument is made that the bulk thermodynamics of polymeric systems are poorly understood at this time since they are strongly dependent on local aspects, such as chain structure, stiffness and packing, which are not captured accurately by coarse-grained polymeric theories. Consequently, computer simulation on realistic chain models would represent an accurate technique to capture the effects of local structure and unpacking on thermodynamics properties. In addition to PVT equation of state properties, which can be obtained through standard computer simulation methods, newly proposed techniques will be used to enumerate the thermodynamic properties, especially the phase behavior, of these systems. In parallel the effect of film thickness on the phase separation in ultrathin polymer blends films will be studied. It is emphasized that a good understanding of this fundamentally important physical phenomenon is predicated on understanding, not only the surface behavior of polymeric systems, but also the bulk thermodynamics. This issue has already been studied in some detail from a theoretical viewpoint and experimental investigations are currently in progress. Finally, a good understanding of this situation also requires knowledge of the steric penalty associated with confining molecules near surfaces, and these aspects will be examined through a study of the alignment of liquid crystalline molecules in the vicinity of flat surfaces. ***