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Phase Behavior and Aggregation in a Catanionic System Dominated by an Anionic Surfactant Containing a Large Rigid Group
Author(s) -
Zhai Zhaolan,
Yan Xinyan,
Xu Ji,
Song Zhanqian,
Shang Shibin,
Rao Xiaoping
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201800628
Subject(s) - micelle , pulmonary surfactant , phase (matter) , chemical engineering , aqueous solution , bromide , materials science , chemistry , cationic polymerization , polymer chemistry , organic chemistry , engineering
Abstract The phase behavior and aggregates of a catanionic system have been investigated. The anionic surfactants in the mixed systems were sodium N ‐alkylmaleimidepimaric carboxylate (C n ‐MPA‐Na, n =12, 14, 16), which were prepared from rosin and contain a large rigid skeleton and a flexible alkane chain, and the cationic surfactant was cetyltrimethylammonium bromide (CTAB). The phase behavior of the C 14 ‐MPA‐Na/CTAB system transformed sequentially from a viscoelastic solution to an aqueous surfactant two‐phase system (ASTP), an aqueous surfactant three‐phase system (AS3P), and an anisotropic homogeneous phase as the concentration of C 14 ‐MPA‐Na was continuously increased from 10 to 35 m m . The C 16 ‐MPA‐Na/CTAB system showed similar phase behavior, whereas the C 12 ‐MPA‐Na/CTAB system did not form the AS3P system. The corresponding microstructures in the different phases were investigated by using rheology and cryogenic transmission electron microscopy (Cryo‐TEM). The aggregates in the viscoelastic solutions are thread‐like, annular, and worm‐like micelles. The microstructures in the upper phase of the ASTP are worm‐like micelles, and in the lower phase are spherical and rod‐like micelles. The aggregates in the upper and lower phases of the AS3P are worm‐like micelles and spherical and rod‐like micelles, respectively. The aggregates in the middle phase of the AS3P and the anisotropic homogeneous phase are sponge‐like micelles. The clear Cryo‐TEM images of the sponge‐like micelles are presented.