Pore network design: DPD-Monte Carlo study of solvent diffusion dependence on side chain location

Phase separation within water containing polymer membranes is studied by dissipative particle dynamics (DPD). The polymers are composed of hydrophobic backbone A beads to which ([A-C] or [A-A-C-C]) side chains are attached with a hydrophilic (C) end moiety. Water diffusion through the water containing pores is modeled by Monte Carlo (MC) tracer diffusion. Several polymeric architectures are considered which differ in the way side chains are attached along the polymer backbones. In total 120 pore morphologies are stored on file and probed by MC tracer diffusion calculations. For membranes of the same ion exchange capacity diffusion is highest for architectures for which two side chains are branching off from the backbone sites as compared to architectures for which only one side chain is branching off. This conclusion is also obtained from diffusion constants derived from mean squared displacements of water during the DPD simulations. The intrinsic high polymer mobility in conventional DPD results in water diffusivities that are much higher than those obtained from the MC calculations. Assigning higher masses to the polymer beads results in significant decrease in water bead motion. (C) 2014 Published by Elsevier B.V.