Coarse Grained Modeling for Diffusion of Macromolecules in Biphasic Systems*

Bicontinuous Interfacially Jammed Emulsion Gels (Bijels) are biphasic structures with potential applications in catalysis, separation processes, and tissue engineering.¹ Here we use Dissipative Particle Dynamics (DPD) simulations via the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)^2,3 to explore macromolecule transport within Bijel structures. Our system consists of two immiscible fluid phases, water and diethyl phthalate, stabilized by neutrally wetting nanoparticles. To validate our results, we model macromolecules by incorporating intra-bead interaction potentials, focusing on conformational characteristics like the radius of gyration. Machine learning regression models are employed to predict the final conformation based on the DPD model parameters. Dynamic phenomena, including macromolecule diffusivity in both water and oil phases, are investigated. A protocol is developed to enhance the reliability and consistency of DPD computations. The dependence of diffusivity on viscous effects is examined using the Stokes-Einstein analogy, validating our studies. Ultimately, our model investigates the migratory behavior of hydrophilic compounds from the oil phase to the water phase, providing insights essential for optimizing Bijel-based processes.

REFERENCES

1. Cha, S. et al. Scientific Reports 2019, 9 (1), 6363.

2. Nguyen, T.X.D., et al.,  Polymers 2022 14(3) Art 543.

3. Vu, T.V., et al., J. Colloid & Interf. Sci. 2019, 553, 50-58.