Regensburg 2025 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Modeling and Simulation of Soft Matter III

CPP 28.2: Vortrag

Mittwoch, 19. März 2025, 15:15–15:30, H34

Simulation of the fabrication of integral asymmetric polymer membranes using continuum modeling — •Gregor Häfner and Marcus Müller — University of Göttingen, Germany

Integral asymmetric polymer membranes represent a promising class of functional macromolecular systems with a wide range of potential applications, including water purification and protein separation. Their synthesis is achieved through a two-step procedure: (i) the controlled self-assembly of diblock copolymers upon solvent evaporation, to form a cylindrical morphology that is oriented perpendicular to the solution-gas interface. (ii) a solvent-non-solvent exchange, raising the polymer concentration above its glass transition, thereby freezing the matrix phase while allowing the entry of the non-solvent through the cylindrical minority domains. Below, the non-solvent macrophase separates from the polymer to form a porous sub-structure.

In order to gain insight into the physical processes, we perform computer simulations. A continuum model is employed which treats the local concentrations as order parameters and minimizes a free-energy functional. In the limit of high viscosity, the dynamics are purely diffusive, enabling comparison with a particle-based model. We use the continuum model to optimize the final membrane morphology and identifying optimal parameter regions and dependencies. Additionally, this model enables the treatment of finite viscosities. We demonstrate that in the presence of a bariocentric flow, the frozen top layer can be transported downwards to prevent the formation of macro voids beneath the isoporous top layer.

Keywords: Self-Assembly; Diblock Copolymers; Simulation; Filter Membranes