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Behavior of Smart Surfactants in Stabilizing pH‐Responsive Emulsions
Author(s) -
Pei Xiaomei,
Zhang Sheng,
Zhang Wanqing,
Liu Pei,
Song Binglei,
Jiang Jianzhong,
Cui Zhenggang,
Binks Bernard P.
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202013443
Subject(s) - cationic polymerization , pulmonary surfactant , pickering emulsion , emulsion , chemistry , aqueous two phase system , chemical engineering , dispersion (optics) , nanoparticle , aqueous solution , emulsion polymerization , aqueous medium , phase (matter) , polymerization , alkyl , polymer chemistry , organic chemistry , polymer , engineering , biochemistry , physics , optics
Newly structured pH‐responsive smart surfactants (N + ‐(n)‐N, n =14, 16) from alkyl trimethylammonium bromides are reported. In neutral and alkaline media N + ‐(n)‐N behaves as a normal cationic surfactant and stabilizes conventional emulsions alone, as well as Pickering emulsions and oil‐in‐dispersion emulsions together with oppositely and similarly charged nanoparticles, respectively. In acidic media N + ‐(n)‐N becomes a hydrophilic Bola‐type surfactant, N + ‐(n)‐NH + , and is an inferior emulsifier either when used alone or together with charged nanoparticles, resulting in demulsification. N + ‐(n)‐NH + returns to the aqueous phase alone or together with nanoparticles after demulsification without contaminating the oil phase, and the aqueous phase can be recycled when triggered by pH change. This protocol is a green process and leads to preparation of various temporarily stable emulsions which are often used in emulsion polymerization, heterogeneous catalysis, and oil transportation.