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Detailed Molecular Dynamics Simulation of the Structure and Self‐Diffusion of Linear and Cyclic n ‐Alkanes in Melt and Blends
Author(s) -
Alatas Panagiotis V.,
Tsalikis Dimitrios G.,
Mavrantzas Vlasis G.
Publication year - 2017
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.201600049
Subject(s) - molecular dynamics , self diffusion , thermodynamics , diffusion , force field (fiction) , chemistry , alkane , intermolecular force , conformational isomerism , radial distribution function , isothermal process , molecule , computational chemistry , organic chemistry , hydrocarbon , physics , self service , marketing , quantum mechanics , business
Results are presented for the density, free volume, self‐diffusion, structure, and conformation of short linear and cyclic n ‐alkanes in their own melt and in blends at equal carbon number from detailed atomistic molecular dynamics (MD) simulations in the isothermal‐isobaric (NPT) statistical ensemble using the explicit‐atom optimized potentials for liquid simulations (OPLS‐AA) force‐field. In agreement with experimental data reported in an earlier study by von Meerwall et al. (2003), cyclic alkanes are characterized by higher densities and diffuse more slowly than their equivalent linear alkanes. Their configurations are also dominated by certain conformers whose exact shape depends on the molecular length n of the cyclic alkane. The smaller the value of n the more symmetric the shape of these conformers. The MD results support the findings of von Meerwall et al. (2003) that the overall (single average) diffusion coefficient of linear and cyclic alkanes in their blend is equal to the weight‐average of the diffusion coefficients of the neat species at the same temperature. Simulation results are also presented for the average size, individual diffusivities, and intermolecular CC pair distribution function of the two components (linear and cyclic) as a function of molecular weight and blend concentration in cyclic molecules.