Speaker
Description
Partitioning of (bio)materials in polymer mixtures underlies processes ranging from cellular organization to industrial separation technologies. Despite its importance, the physical mechanisms governing phase coexistence and interfacial structure are not yet fully understood.
As a controllable model system, we first investigate a demixing mixture of coarse-grained polymers containing magnetic nanoparticles using particle-based simulations [1]. An external magnetic field enables controlled modulation of the interface, providing a tunable platform to quantify interfacial properties such as surface tension and to analyze how particle size and interactions influence partitioning across coexisting phases. Throughout, the model parameters are chosen to ensure qualitative and semi-quantitative consistency with experimental behavior.
To generalize these insights, we develop an improved classical density functional theory (DFT) framework with refined free-energy functionals and an algorithm capable of resolving phase coexistence in mixtures containing n polymers and m colloidal components across multiple phases [2]. While particle-based simulations become computationally prohibitive for spanning the large parameter space, the DFT approach provides a scalable description of multicomponent systems and is quantitatively benchmarked against simulations, showing very good agreement.
[1] A. Scacchi, C. Rigoni, M. Haataja, J. V. I. Timonen, M. Sammalkorpi, "A corase-grained model for aqueous two-phase systems: Application to ferrofluids", Journal of Colloid and Interface Science 686, (2025).
[2] V. A. Varma & A. Scacchi, "General approach for partitioning and phase separation in macromolecular coexisting phases", arXiv preprint arXiv:2509.14392, (2025).