Molecular Simulation of Permeation of Small Penetrants through Membranes.
2. Solubilities.
Y. Tamai, H. Tanaka, K. Nakanishi
Macromolecules, 28, 2544-2554 (1995)
Abstract
The excess chemical potentials of methane, water, and ethanol
in poly(dimethylsiloxane) (PDMS) and polyethylene (PE)
were calculated by the Widom method.
The excess chemical potentials of water and ethanol
in aqueous ethanol solutions (0, 50, 100 wt %)
were also calculated by the Shing-Gubbins method.
The excluded volume map sampling (EVMS) method and
the continuum configurational bias (CCB) method were
used to increase the efficiency of sampling.
In spite of the polarity and
the internal degrees of freedom of the molecules,
the excess chemical potentials could be calculated
with a small statistical error.
The solubilities of methane, water, and ethanol in the polymers
were calculated from excess chemical potentials.
Permeation rates calculated from diffusion coefficients and solubilities
were in reasonable agreement with experimental data.
The free volume cluster of each system was analyzed
and was related to the permeation of small penetrants in the membranes.
Copyright (c) 1997 Yoshinori Tamai