title: Highly effective emulsification/demulsification with a CO2-switchable superamphiphile.
abstract: This article reports a systematic study on a highly CO2-responsive superamphiphile (D-OA) in preparation of CO2-switchable oil-in-water emulsions. The D-OA was assembled with Jeffamine D 230 and oleic acid (HOA) via electrostatic interaction, which was characterized using FT-IR, (1)HNMR, surface tension, and interfacial tension techniques. The assembled gemini-like superamphiphile D-OA was shown to have a low cmc value and adsorb quickly at the paraffin oil/water interface, decreasing the interfacial tension effectively. Highly stable O/W emulsions were obtained by mixing D-OA aqueous solution and paraffin oil. After bubbling CO2 through the stable emulsions for just 20s, quick phase separation was observed; while upon removal of CO2 by bubbling N2 at 60°C, stable emulsions were recreated. The reversible assembly and disassembly of the D-OA superamphiphile by adding or removing CO2 were considered as the cause of demulsification and re-emulsification processes. The rapid and complete demulsification of the system in response to CO2 addition and removal may have potential applications in emulsion-based fabrication/separation and enhanced oil recovery processes.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong 250100, PR China.
authors.forename: Peipei
authors.initials: P
authors.lastname: Xu
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong 250100, PR China.
authors.forename: Zengzi
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada; Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 1000084, PR China.
authors.forename: Zhenghe
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong 250100, PR China.
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong 250100, PR China. Electronic address: djsun@sdu.edu.cn.
authors.forename: Dejun
authors.initials: D
authors.lastname: Sun
keywords: Assembly and disassembly; CO(2) switchable; Rapid demulsification; Superamphiphile