Molecular simulation study on sorption and diffusion processes in polymeric pervaporation membrane materials

Abstract

Since MD simulations of membrane separation processes of aqueous/organic solutions lead to reasonable results that are in good agreement with experimental investigations an approach has been made to apply this method also for organic/organic membrane separation. In this connection the separation of a model feed mixture of 20 wt% benzene and 80 wt% n-heptane with dense amorphous polymer membranes was simulated utilising molecular modelling techniques. Special modifications of standard polymers such as polymethacrylates and polysiloxanes were investigated. It could be demonstrated that MD simulations of polymer–feed interface models can reproduce at least qualitatively important experimental results from related membrane pervaporation processes. These models are therefore suited in principle to obtain a better insight in the atomistic mechanisms of pervaporation. In addition, the knowledge about the underlying diffusion mechanism could be improved.

Keywords:

• Polymeric membranes
• Pervaporation
• Molecular dynamics simulations
• CAMM

Acknowledgements

We thank Dr Schwarz (GKSS) and Regine Apostel (GKSS) for the pervaporation measurements on PDMS films and Christine Dannenberg (Technical University of Berlin) for the measured density values. We would like to acknowledge that parts of the work were supported by the European Commission “Growth” Program, “PERMOD—Molecular modelling for the competitive molecular design of polymer materials with controlled permeability properties.”, Contract #G5RD-CT-2000-200.