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

Masanari Nagasaka; Fumitoshi Kumaki; Yifeng Yao; Jun-Ichi Adachi; Kenji Mochizuki

doi:10.1039/d4cp00676c

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

Phys Chem Chem Phys. 2024 May 8;26(18):13634-13638. doi: 10.1039/d4cp00676c.

Authors

Masanari Nagasaka^{1

2}, Fumitoshi Kumaki³, Yifeng Yao⁴, Jun-Ichi Adachi^{3

5}, Kenji Mochizuki⁴

Affiliations

¹ Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan. nagasaka@ims.ac.jp.
² Molecular Science Program, Graduate Institute for Advanced Studies, SOKENDAI, Myodaiji, Okazaki 444-8585, Japan.
³ Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
⁴ Department of Chemistry, Zhejiang University, Hangzhou, 310028, P. R. China.
⁵ Materials Structure Science Program, Graduate Institute for Advanced Studies, SOKENDAI, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.

PMID: 38685819
DOI: 10.1039/d4cp00676c

Abstract

The cononsolvency mechanism of poly(N-isopropylacrylamide) (PNIPAM), dissolving in pure methanol (MeOH) and water (H₂O) but being insoluble in MeOH-H₂O 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.