(362j) Water Reorganization Drives Liquid—Liquid Phase Separation
AIChE Annual Meeting
2023
2023 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Faculty Candidates in CoMSEF/Area 1a, Session 1
Monday, November 6, 2023 - 9:30am to 9:40am
Using coarse-grained simulation and thermodynamics analysis, we find that solvent (water) reorganization is a key component to the entropy change in the LLPS. We resolve the long-standing controversy involving the driving force for polyelectrolyte complex coacervation including the entropy contribution in electrostatic interaction, manifested in the temperature-dependent dielectric constant of water. Our results show that polycationâpolyanion complexation in weakly to moderately charged polymers is strongly entropy-driven with negligible energetic contribution, consistent with experiments. On the EEC puzzle, we find that the solvent reorganization is the major source during the binding process, arising from the temperature-dependent hydrophobic interactions. For association in a lower critical solution temperature (LCST) system, the solvent reorganization entropy dominates the favorable free energy change, at the expense of energy. For association in an upper critical solution temperature (UCST) system, the free energy change is dominated by the energy due to solvent reorganization, at the expense of entropy.
Our results highlight the central role of water reorganization in the driving force of LLPS, whose contributions need to be accounted for to properly interpret LLPS thermodynamics. In addition, our work hints at the possibility of harnessing water reorganization entropy/enthalpy for improved binding affinity and thermal stability in molecular design.