Molecular dynamics simulation of structure, thermodynamic, dynamic and hydrocarbon permeability properties of silicon-containing elastomers with promising membrane material behavior

Detailed ab initio quantum mechanics calculations on corresponding monomers that appeared in the literature are used for the parameterization of the bonded and non-bonded local intramolecular force field. For the intermolecular and non-bonded non-local intramolecular interactions, parameters were obtained from accurate force fields proposed in the literature for similar compounds. The force field was used subsequently for the calculation of thermodynamic, structure, and dynamic properties of two homopolymers, i.e., poly(dimethylsilamethylene) and poly(dimethylsilatrimethylene), and their alternating copolymer. Polymer systems of different molecular weights were simulated. Experimental data available for these polymers were very limited. In all cases, simulation results were in good agreement with these data. Furthermore, simulation results agreed very well with empirical macroscopic correlations for the properties under consideration that are used widely for rubbery polymers. The solubilities of various n-alkanes from methane to n-hexane at 300 K were calculated using the Widom test particle insertion technique. The diffusion coefficients of the various n-alkanes were calculated from long Molecular Dynamics simulation runs. In all cases, simulation results were in good agreement with published data. This is an abstract of a paper presented at the 2006 AIChE National Meeting (San Francisco, CA 11/12-17/2006).