Visualizing Water Monomers and Chiral OH-(H2O) Complexes Infiltrated in a Macroscopic Hydrophobic Teflon Matrix

Jiahui Zhang; Ruoqi Pei; Junjun Tan; Zijian Ni; Shuji Ye; Yi Luo

doi:10.1021/jacs.3c09950

Visualizing Water Monomers and Chiral OH^-(H₂O) Complexes Infiltrated in a Macroscopic Hydrophobic Teflon Matrix

J Am Chem Soc. 2023 Dec 13;145(49):26925-26931. doi: 10.1021/jacs.3c09950. Epub 2023 Dec 4.

Authors

Jiahui Zhang¹, Ruoqi Pei¹, Junjun Tan², Zijian Ni¹, Shuji Ye^{1

2}, Yi Luo^{1

2}

Affiliations

¹ Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, China.
² Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China.

PMID: 38048434
DOI: 10.1021/jacs.3c09950

Abstract

Insights into the interaction of fluoroalkyl groups with water are crucial to understanding the polar hydrophobicity of fluorinated compounds, such as Teflon. While an ordered hydrophobic-like 2D water layer has been demonstrated to be present on the surface of macroscopically hydrophobic fluorinated polymers, little is known about how the water infiltrates into the Teflon and what is the molecular structure of the water infiltrated into the Teflon. Using highly sensitive femtosecond sum frequency generation vibrational spectroscopy (SFG-VS), we observe for the first time that monomeric H₂O and chiral OH^-(H₂O) complexes are present in macroscopically hydrophobic Teflon. The species are inhomogeneously distributed inside the Teflon matrix and at the Teflon surface. No water clusters or single-file water "wires" are observed in the matrix. SFG free induction decay (SFG-FID) experiments demonstrate that the OH oscillators of physically absorbed molecular water at the surface dephase on the time scale of <230 fs, whereas the water monomers and hydrated hydroxide ions infiltrated in the Teflon matrix dephase much more slowly (680-830 fs), indicating that the embedded monomeric H₂O and OH^-(H₂O) complexes are decoupled from the outer environment. Our findings can well interpret ultrafast water permeation through fluorous nanochannels and the charging mechanism of Teflon, which may tailor the desired applications of organofluorines.