Mechanism of poly(-isopropylacrylamide) cononsolvency in aqueous methanol solutions explored oxygen K-edge X-ray absorption spectroscopy.

The cononsolvency mechanism of poly(-isopropylacrylamide) (PNIPAM), dissolving in pure methanol (MeOH) and water (HO) but being insoluble in MeOH-HO mixtures, was investigated by O K-edge X-ray absorption spectroscopy (XAS). The cononsolvency emerges from the aggregation of PNIPAM with MeOH clusters, leading to the collapse of the hydrophobic hydration of PNIPAM.