A Library of Thermoresponsive, Coacervate-Forming Biodegradable Polyesters

We report on a new class of thermoresponsive biodegradable polyesters (TR-PE) inspired by polyacrylamides and elastin-like proteins (ELPs). The polyesters display reversible phase transition with tunable cloud point temperatures (T-cp) in aqueous solution as evidenced by UV-vis spectroscopy, H-1 NMR, and DLS measurements. These polyesters form coacervate droplets above their lower critical Solution temperature (LCST). The T-cp, of the polyesters is influenced by the solutes such as urea, SDS, and NaCl. The T-cp, of the copolymers shows a linear correlation with the composition of the polyesters indicating the ability to tune the phase change temperature. We also show that such thermoresponsive coacervates are capable of encapsulating small molecules such as Nile Red. Furthermore, the polyesters are hydrolytically degradable.