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Vesicles of a New Salt‐Free Cat‐anionic Fluoro/Hydrocarbon Surfactant System
Author(s) -
Li Xin,
Dong Shuli,
Jia Xiangfeng,
Song Aixin,
Hao Jingcheng
Publication year - 2007
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.200700778
Subject(s) - cationic polymerization , pulmonary surfactant , vesicle , chemistry , hydrocarbon , fluorocarbon , micelle , dynamic light scattering , aqueous solution , protonation , polymer chemistry , organic chemistry , inorganic chemistry , materials science , membrane , nanotechnology , nanoparticle , ion , biochemistry
Weakly basic tetradecyldimethylaminoxide (C 14 DMAO) molecules can be protonated to form a cationic surfactant, C 14 DMAOH + , by an acidic fluorocarbon surfactant, an 8‐2‐fluorotelomer unsaturated acid (C 7 F 15 CFCHCOOH), to form a salt‐free cationic and anionic (cat‐anionic) fluoro/hydrocarbon surfactant system in aqueous solution. The high Krafft point of C 7 F 15 CFCHCOOH was largely reduced as a result of being mixed with a C 14 DMAO micelle solution. A study of the phase behavior of the new salt‐free cat‐anionic fluoro/hydrocarbon surfactant system clearly indicates the existence of a birefringent Lα‐phase region at (25.0±0.1) °C. The birefringent Lα phase consists of vesicles, which include uni‐ and multilamellar vesicles with one to dozens of shells, and oligovesicular vesicles, as demonstrated by freeze‐fracture and cryo‐transmission electron microscopy (FF‐ and cryo‐TEM) images. The size distribution and structural transitions in the salt‐free cat‐anionic fluoro/hydrocarbon surfactant system were studied by dynamic light scattering (DLS) and 1 H and 19 F NMR spectroscopy. The formation of a salt‐free cat‐anionic vesicle phase could be induced by the strong electrostatic interaction between the cationic hydrocarbon C 14 DMAOH + and the anionic fluorocarbon C 7 F 15 CFCHCOO − , which provided evidence that the electrostatic interaction between the cationic and anionic surfactants is larger than the nonsynergistic interaction between the stiff fluorocarbon and the soft hydrocarbon chains of the surfactants.