Equation-of-State Model for Temperature-Responsive Polymers with Tunable Response Onset

The phase behavior of aqueous solutions of temperature-responsive (ethylene oxide)/ethylene copolymers with tunable lower critical solution temperatures (LCST) is explored using an equation of state approach. The LCST in water of these polymers is tailored by their chemical composition, specifically by the balance of hydrophilic to hydrophobic groups in the polymer. The general formalism of the lattice-fluid with hydrogen-bonding theory, adjusted here to account for multiple types of hydrogen bonds, is employed, and the theoretical predictions are compared with experimental systems. The developed theoretical model is shown to be effective in describing the phase behavior of these systems, and the model parameters seem to be transferable between different homologous copolymer series.