(437a) Molecular Dynamics Simulation of Structure, Thermodynamic, Dynamic and Hydrocarbon Permeability Properties of Silicon-Containing Elastomers with Promising Membrane Material Behavior

Molecular Dynamics is used for the simulation of silicon containing polymers with promising membrane material properties. An atomistic force-field is developed for the description of bond bending, torsional angle variation and non-bonded intra- and intermolecular interactions. Detailed ab initio quantum mechanics calculations on corresponding monomers that appeared recently 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 are obtained from accurate force fields proposed in the literature for similar compounds. The force field is used subsequently for the calculation of thermodynamic, structure and dynamic properties of two homopolymers, namely poly(dimethylsilamethylene) and poly(dimethylsilatrimethylene), and their alternating copolymer. A wide range of temperatures and pressures is examined. Polymer systems of different molecular weights are simulated. Experimental data available for these polymers are very limited. In all cases, simulation results are in good agreement with these data. Furthermore, simulation results agree 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 are calculated using the Widom test particle insertion technique. Finally, the diffusion coefficients of the various n-alkanes are calculated from long Molecular Dynamics simulation runs, of duration up to 100 ns. In all cases, simulation results are in good agreement with literature experimental data.

References

V.E. Raptis, I.G. Economou, D.N. Theodorou, J. Petrou and J.H. Petropoulos, "Molecular Dynamics Simulation of Structure and Thermodynamic Properties of Poly(dimethyl-silamethylene) and Hydrocarbon Solubility Therein: Towards the Development of Novel Membrane Materials for Hydrocarbon Separation", Macromolecules, 37(3), 1102-1112 (2004).

I.G. Economou, V.E. Raptis, V.S. Melissas, D.N. Theodorou, J. Petrou and J.H. Petropoulos, “Molecular Simulation of Structure, Thermodynamic and Transport Properties of Polymeric Membrane Materials for Hydrocarbon Separation”, Fluid Phase Equil., 228-229, 15 – 20 (2005).

Z.A. Makrodimitri, V.E. Raptis and I.G. Economou, “Molecular Dynamics Simulation of Structure, Thermodynamic and Dynamic Properties of Poly(dimethylsilamethylene), Poly(dimethylsilatri-methylene) and their Alternating Copolymer”, J. Phys. Chem. B, 110(32), 16047 – 16058 (2006).