Revisiting differences in the thermoresponsive behavior of PNIPAAm and PMEO2MA aqueous solutions

Abstract

In this work, we synthesized PNIPAAm and poly[2-(2-methoxyethoxy)ethyl methacrylate] (PEG analogue) with a similar degree of polymerization by ATRP. Their thermoresponsive behaviors in aqueous solution were inspected with phase diagrams, rheological properties and static/time resolved fluorescence analyses. We found that the gelation capability of the PNIPAAm solution was far superior to the PMEO₂MA solution due to more pronounced physical interactions between PNIPAAm chains, whereas for PMEO₂MA, weak intermolecular interactions fail to result in gelling in the selected concentration range during heating. This distinct property suggests that the PNIPAAm solution will be more suitable for use as an injectable embolic or drug loading material; while thermoresponsive PEG analogues can be a beneficial supplement or even alternative to PNIPAAm in non-thermogelling applications.