title: Electrocapillary Phenomena at Edible Oil/Saline Interfaces.
abstract: Interfacial tension between edible oil and saline was measured under applied electric fields to understand the electrocapillary phenomena at the edible oil/saline interfaces. The electric responses of saline droplets in edible oil were also observed microscopically to examine the relationship between the electrocapillary phenomena and interfacial polarization. When sodium oleate (SO) was added to edible oil (SO-oil), the interfacial tension between SO-oil and saline decreased. However, no decrease was observed for additive-free oil or oleic acid (OA)-added oil (OA-oil). Microscopic observations suggested that the magnitude of interfacial polarization increased in the order of additive-free oil < OA-oil < SO-oil. The difference in electrocapillary phenomena between OA- and SO-oils was closely related to the polarization magnitude. In the case of SO-oil, the decrease in interfacial tension was remarkably larger for saline (pH 5.4~5.6) than that for phosphate-buffered saline (PBS, pH 7.2~7.4). However, no difference was observed between the electric responses of PBS and saline droplets in SO-oil. The difference in electrocapillary phenomena for PBS and saline could not be simply explained in terms of polarization magnitude. The ratio of ionized and non-ionized OA at the interfaces changed with the saline pH, possibly leading to the above difference.
authors.affiliation: Dynamic Functional Materials Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nishimura
authors.forename: Takuya
authors.initials: T
authors.lastname: Ohzono
authors.forename: Kohei
authors.initials: K
authors.lastname: Shoji
authors.forename: Shin
authors.initials: S
authors.lastname: Yagihara
authors.forename: Masafumi
authors.initials: M
authors.lastname: Hayashi
authors.forename: Hisao
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D055590:Electromagnetic Phenomena; D058874:Electrowetting; D019301:Oleic Acid / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry*; D000074262:Rapeseed Oil; D012965:Sodium Chloride / Q000737:chemistry*; D013500:Surface Tension
chemical_list: D010938:Plant Oils; D000074262:Rapeseed Oil; D019301:Oleic Acid; C013173:osteum; D012965:Sodium Chloride