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Viscosity Adjustment of Aqueous Micellar Solutions of Gemini Surfactants by Interaction with Additional Surfactants
Author(s) -
Liu Jinyan,
Zhao Jianxi
Publication year - 2010
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-009-1132-8
Subject(s) - chemistry , pulmonary surfactant , micelle , aqueous solution , ammonium bromide , cationic polymerization , bromide , viscosity , steric effects , ether , micellar solutions , molecule , polymer chemistry , inorganic chemistry , organic chemistry , thermodynamics , biochemistry , physics
Abstract The viscosity of aqueous micellar solutions depends on the size and shape of the aggregates and thus can be adjusted by addition of another surfactant interacting with the original component, which alters the geometry of the molecule‐pair consisting of two surfactants and influences strongly the size and shape of the mixed micelles. Ethanediyl‐α,ω‐bis(dimethyl dodecyl ammonium bromide), referred to as C 12 ‐2‐C 12 ·2Br, forms generally large micelles. Addition of a cationic surfactant (dodecyltrimethylammonium bromide, C 12 TMABr) or a nonionic surfactant (alkyl polyoxyethylene ether, C m E n ), the mixed micelle size is reduced violently since the electrostatic repulsion between the same charged heads of C 12 ‐2‐C 12 ·2Br and C 12 TMABr or the steric hindrance of the PEO chain of C m E n in the palisade layers of the mixed micelle, which leads to a decrease in the packing parameter P of the molecule‐pair. As a result, the zero‐shear viscosity ( η 0 ) of the mixed solution reduces rapidly. In contrast, on adding an oppositely charged surfactant, η 0 of the mixed solution increases strongly since the P of the molecule‐pair increases through electrostatic attraction between the oppositely charged heads. The typical cases occur in the mixtures of the anionic gemini surfactant, O , O ′‐bis(sodium 2‐lauricate)‐ p ‐benzenediol C11 p PHCNa, and the cationic surfactant C 12 ‐2‐C 12 ·2Br, C 12 TMABr or its homologue with a different size of heads.