Brian Carrick

The behavior of polymer solutions has been widely explored, yet systems involving ionic liquids remain poorly understood due to their unique interactions. Few complete compositional phase diagrams have been published for these systems, and to our knowledge, no diagrams involving pyrrolidinium-based ionic liquids have been explored. In this work, we examine the impact of molecular weight on the lower critical solution temperature phase behavior of poly(benzyl methacrylate) (PBzMA) in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide within the solvent-rich regime of its phase diagram. The transition between a clear, homogenous phase and a cloudy, biphasic solution was assessed via cloud point measurements. The sharp phase transition (on the order of seconds) observed with this technique suggests rapid de-solvation of the polymer upon reaching the phase separation temperature (TCP). Furthermore, TCP was determined to be a good approximation for the system’s binodal, or coexistence, curve due to the narrow hysteresis observed in the transmittance curves upon heating and cooling, as well as the reversibility of the phase separation over several thermal cycles. These exciting results have revealed the system’s critical composition lies above 40 wt% PBzMA, far away from the theoretical 5 – 7 wt% predicted by Flory-Huggins solution theory, and that molecular weight has no influence on the phase separation of this system under semi-dilute conditions.