TY - JOUR
T1 - Self-organization of double-chained and pseudodouble-chained surfactants
T2 - Counterion and geometry effects
AU - Marques, E. F.
AU - Regev, O.
AU - Khan, A.
AU - Lindman, B.
N1 - Funding Information:
E.F.M. is grateful to C.I.Q.-U.P. (linha 5), F.C.T., Portugal and VR, The Swedish Research Council, for financial support. Valuable discussions with M.G. Miguel and H. Wennerström throughout the years are kindly acknowledged.
PY - 2003/2/28
Y1 - 2003/2/28
N2 - Self-organization in aqueous systems based on ionic surfactants, and their mixtures, can be broadly understood by a balance between the packing properties of the surfactants and double-layer electrostatic interactions. While the equilibrium properties of micellar systems have been extensively studied and are understood, those of bilayer systems are less well characterized. Double-chained and pseudodouble-chained (or catanionic) surfactants are among the amphiphiles which typically form bilayer structures, such as lamellar liquid-crystalline phases and vesicles. In the past 10-15 years, an experimental effort has been made to get deeper insight into their aggregation patterns. With the double-chained amphiphiles, by changing counterion, adding salt or adding anionic surfactant, there are possibilities to depart from the bilayer aggregate in a controlled manner. This is demonstrated by several studies on the didodecyldimethylammonium bromide surfactant. Mixtures of cationic and anionic surfactants yield the catanionics, surfactants of the swelling type, and also show a rich phase behavior per se. A variety of liquid-crystalline phases and, in dilute regimes, equilibrium vesicles and different micellar shapes are often encountered. Phase diagrams and detailed structural studies, based on several techniques (NMR, microscopy and scattering methods), have been reported, as well as theoretical studies. The main features and conclusions emerging from such investigations are presented.
AB - Self-organization in aqueous systems based on ionic surfactants, and their mixtures, can be broadly understood by a balance between the packing properties of the surfactants and double-layer electrostatic interactions. While the equilibrium properties of micellar systems have been extensively studied and are understood, those of bilayer systems are less well characterized. Double-chained and pseudodouble-chained (or catanionic) surfactants are among the amphiphiles which typically form bilayer structures, such as lamellar liquid-crystalline phases and vesicles. In the past 10-15 years, an experimental effort has been made to get deeper insight into their aggregation patterns. With the double-chained amphiphiles, by changing counterion, adding salt or adding anionic surfactant, there are possibilities to depart from the bilayer aggregate in a controlled manner. This is demonstrated by several studies on the didodecyldimethylammonium bromide surfactant. Mixtures of cationic and anionic surfactants yield the catanionics, surfactants of the swelling type, and also show a rich phase behavior per se. A variety of liquid-crystalline phases and, in dilute regimes, equilibrium vesicles and different micellar shapes are often encountered. Phase diagrams and detailed structural studies, based on several techniques (NMR, microscopy and scattering methods), have been reported, as well as theoretical studies. The main features and conclusions emerging from such investigations are presented.
KW - Bilayers
KW - Catanionic surfactants
KW - Double-chained surfactants
KW - Electrostatic interactions
KW - Phase behavior
UR - http://www.scopus.com/inward/record.url?scp=0037469894&partnerID=8YFLogxK
U2 - 10.1016/S0001-8686(02)00068-4
DO - 10.1016/S0001-8686(02)00068-4
M3 - Article
AN - SCOPUS:0037469894
SN - 0001-8686
VL - 100-102
SP - 83
EP - 104
JO - Advances in Colloid and Interface Science
JF - Advances in Colloid and Interface Science
IS - SUPPL.
ER -