Polymer Partitioning in Bijels and Its Application for mRNA Encapsulation

Polymers at interfaces are central to reactive separations [1], emulsion stabilization [2], and liquid-liquid extraction [3]. To better understand the governing parameters, we employ Dissipative Particle Dynamics (DPD) simulations in LAMMPS [4-6] to investigate the interfacial behavior of hydrophilic short polymers, such as mRNA in bijels [7]. Partition coefficients are computed for different polymer conformations, with a focus on solvent compatibility captured by the Flory-Huggins parameter (χ). Interfacial energetics and desorption mechanisms are examined, including analogies to nanoparticle detachment in jammed systems [8]. The effect of polymer size on partitioning is also explored, revealing size-dependent trends. A master curve is proposed to predict partition coefficients based on key variables.

In a case study, we extend this framework to the lipophilization of mRNA in a dual-oil system. A concentration vs. affinity map is generated, and the resulting multiphasic microstructures are analyzed to evaluate their impact on separation efficiency.

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