Molecular flexibility effects upon liquid dynamics

JV Heffernan and J Budzien and AT Wilson and RJ Baca and VJ Aston and F Avila and JD Mccoy and DB Adolf, JOURNAL OF CHEMICAL PHYSICS, 126, 184904 (2007).

DOI: 10.1063/1.2730502

Simulation results for the diffusive behavior of polymer chain/penetrant systems are analyzed. The attractive range and flexibility of simple chain molecules were varied in order to gauge the effect on dynamics. In all cases, the dimensionless diffusion coefficient, D-*, is found to be a smooth, single-valued function of the packing fraction, eta. The functions D-*(eta) are found to be power laws with exponents that are sensitive to both chain stiffness and particle type. For a specific system type, the D-*'s for both penetrant and chain-center-of-mass extrapolate to zero at the same packing fraction, eta(0). This limiting packing fraction is interpreted to be the location of the glass transition, and (eta(0)-eta), the distance to the glass transition. (C) 2007 American Institute of Physics.

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