(693l) Investigations into Stimuli-Responsive Polymer Behaviors with the Novel Flory-Huggins-Potts Framework

Thermoresponsiveness and cononsolvency hold both fundamental and technological importance, but the essential physics driving their intriguing behavior is not wholly understood. We introduce a lattice framework that incorporates elements of Flory-Huggins solution theory and the $q$-state Potts model to investigate the phase behavior of polymer solutions and single-chain conformational characteristics. Importantly, and by contrast to many prior theoretical approaches, the framework does not employ any temperature- or composition-dependent parameters. With this minimal Flory-Huggins-Potts framework, we show that orientation-dependent interactions, specifically between monomer segments and solvent particles, are alone sufficient to observe complex phase behavior. Signatures of emergent phase behavior are found in single-chain Monte Carlo simulations, which display heating- and cooling-induced coil-globule transitions linked to energy fluctuations. The framework also capably describes a range of experimental systems. This work provides new insights regarding the microscopic physics that underpin complex thermoresponsive behavior in polymers.