The cononsolvency mechanism of poly(N-isopropylacrylamide) (PNIPAM), dissolving in pure methanol (MeOH) and water but being insoluble in aqueous MeOH solutions, were investigated by O K-edge XAS with theoretical calculations executed in molecular dynamics simulations and inner-shell calculations. It was found that the cononsolvency emerges from the aggregation of PNIPAM with MeOH clusters owing to the hydrophobic interactions between PNIPAM and MeOH clusters leading to the collapse of the hydrophobic hydration of PNIPAM.
