Poly(2-amino-2-oxazoline)s: a new class of thermoresponsive polymers

In this report, we describe the synthesis and properties of poly(2-dialkylamino-2-oxazoline)s (PAmOx), a new class of thermoresponsive polymers. These polymers were synthesized by acylation of linear polyethyleneimine, as the conventional cationic ring-opening polymerization of the respective monomers led to extensive chain transfer reactions. The hydrophilicity of obtained poly(2-dialkylamino-2-oxazoline)s was highly dependent on the side-chain substituents, ranging from very hydrophilic poly(2-dimethylamino-2-oxazoline) to the hydrophobic poly(2-diisopropylamino-2-oxazoline). Notably, the poly(2-diethylamino-2-oxazoline) (PDEAOx) shows fast-response LCST behavior around room temperature (24 °C), as well as low Tg (−10 °C), which can be beneficial in the construction of new stimuli-responsive biomaterials. Overall, PAmOx represent a novel polymer platform for a wide range of possible applications.