All at the surface: Exploring the surface thermodynamics of polymer clusters through minimal molecular modelling*

Proteins, nucleic acids, and filamentous phages (essentially polymeric molecules) can each nucleate and form molecular clusters, largely as a consequence of liquid-liquid phase separation (LLPS). Biologically, these clusters arise as concentrated nanoscale droplets that are known to form a dynamic environment for important cellular biochemical and physical processes. Despite the importance of these droplets, through their association with disease, and even bacterial antibiotic resistance, the key molecular mechanisms underpinning their formation remain rather incomplete. Here, we explore the role of the interface of these droplets and present novel simulation techniques to explore the thermodynamics of these systems (such as surface tension and excess free energy) from coarse-grained molecular dynamics simulations, based on modern statistical mechanics and polymer physics. These techniques allow us to predict how microscopic properties of the surface help to determine emerging droplet behaviour. Taken together, our framework provides mechanistic insights into how the patterning, shape, and strength of intermolecular interactions between polymeric units determine the size, geometry, and coalescence behaviour of modelled biopolymers.