2026-09-28 東京大学
吸着初期における膜界面での水の組織化、疎水性表面による違いのイメージ図
＜関連情報＞
- https://www.issp.u-tokyo.ac.jp/maincontents/news2.html?pid=32289#
- https://pubs.acs.org/langd5/article/doi/10.1021/acs.langmuir.6c02250/5439658/Hydrophobic-Hydration-at-Fluorinated-and
フッ素化および炭化水素自己組織化単分子膜における疎水性水和のその場軟X線発光分光法および分子動力学シミュレーション による研究 Hydrophobic Hydration at Fluorinated and Hydrocarbon Self-Assembled Monolayers Investigated by In Situ Soft X-Ray Emission Spectroscopy and Molecular Dynamics Simulation
Yusuke Tomiyori;Hisao Kiuchi;Kosuke Funahashi;Wenxiong Zhang;Yoshihisa Harada
Langmuir Published:September 28, 2026
DOI:https://doi.org/10.1021/acs.langmuir.6c02250
Abstract
We investigated the hydrogen-bonding state and spatial distribution of water at hydrophobic self-assembled monolayer (SAM) interfaces formed by fluoroalkyl and hydrocarbon chains using in situ soft X-ray emission spectroscopy (XES) and molecular dynamics (MD) simulations under controlled humidity conditions. Under low water coverage, the hydrocarbon-based SAM exhibited spectral features attributed to isolated water molecules, while the fluorinated SAM showed signatures indicative of tetrahedrally coordinated hydrogen-bond networks. MD simulations revealed that water molecules at the fluorinated SAM interface preferentially populate the second hydration shell around polar functional groups rather than directly occupying the first shell, consistent with the XES observations. Natural bond orbital (NBO) analysis demonstrated that the inductive effect of fluorine suppresses charge localization at the amide group in the fluorinated SAM relative to the hydrocarbon-based SAM, weakening direct water–surface hydrogen bonding and promoting water–water network formation. These results suggest that fluorinated SAM interfaces enhance hydrophobicity, in part, by promoting extended tetrahedral water–water networks characteristic of hydrophobic hydration, rather than by direct water exclusion. These findings provide molecular-level insights into structure–property relationships in SAM-based materials and inform the design of water-repellent surfaces and fluorine-reduced hydrophobic coatings.
