title: Surface properties of a single perfluoroalkyl group on water surfaces studied by surface potential measurements.
abstract: A discriminative study of a single perfluoroalkyl (Rf) group from a bulk material is recently recognized to be necessary toward the total understanding of Rf compounds based on a primary chemical structure. The single molecule and the bulk matter have an interrelationship via an intrinsic two-dimensional (2D) aggregation property of an Rf group, which is theorized by the stratified dipole-arrays (SDA) theory. Since an Rf group has dipole moments along many C-F bonds, a single Rf group would possess a hydrophilic-like character on the surface. To reveal the hydration character of a single Rf group, in the present study, surface potential (ΔV) measurements are performed for Langmuir monolayers of Rf-containing compounds. From a comparative study with a monolayer of a normal hydrocarbon compound, the hydration/dehydration dynamics of a lying Rf group on water has first been monitored by ΔV measurements, through which a single Rf group has been revealed to have a unique "dipole-interactive" character, which enables the Rf group interacted with the water 'surface.' In addition, the SDA theory proves to be useful to predict the 2D aggregation property across the phase transition temperature of 19°C by use of the ΔV measurements.
authors: Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Electronic address: shimoaka@scl.kyoto-u.ac.jp.
authors: Takafumi
authors: T
authors: Shimoaka
authors: Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Electronic address: yuki@env.kuicr.kyoto-u.ac.jp.
authors: Yuki
authors: Y
authors: Tanaka
authors: Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Electronic address: nobutaka@env.kuicr.kyoto-u.ac.jp.
authors: Nobutaka
authors: N
authors: Shioya
authors: Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan. Electronic address: t09301167@gunma-u.ac.jp.
authors: Kohei
authors: K
authors: Morita
authors: Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan. Electronic address: sonoyama@gunma-u.ac.jp.
authors: Masashi
authors: M
authors: Sonoyama
authors: Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan. Electronic address: amii@gunma-u.ac.jp.
authors: Hideki
authors: H
authors: Amii
authors: National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. Electronic address: t.takagi@aist.go.jp.
authors: Toshiyuki
authors: T
authors: Takagi
authors: National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. Electronic address: t.kanamori@aist.go.jp.
authors: Toshiyuki
authors: T
authors: Kanamori
authors: Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Electronic address: htakeshi@scl.kyoto-u.ac.jp.
authors: Takeshi
authors: T
authors: Hasegawa
keywords: Langmuir monolayer; Single perfluoroalkyl chain; Surface potential; Water surface