The effect of chain length on the melting temperature and size of dialkyldimethylammonium bromide vesicles
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Elsevier B.V.
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Differential scanning calorimetry (DSc) and dynamic light scattering (DLS) were used to obtain the gel to liquid-crystalline phase transition temperature (T-m) and the apparent hydrodynamic radius (R-h) of spontaneously formed cationic vesicles of dialkyldimethylammonium bromide salts (CnH2n+1)(2)(CH3)(2)N+center dot Br-, with varying chain lengths. The preparation of cationic vesicles from aqueous solution of these surfactants, for n = 12, 14, 16 and 18 (DDAB, DTDAB, DHDAB and DODAB, respectively), requires the knowledge of the surfactant gel to liquid-crystalline phase transition temperature, or melting temperature (T-m) since below this temperature these surfactants are poorly or not soluble in water. That series of cationic surfactants has been widely investigated as vesicle-forming surfactants, although C-12 and C-18, DDAB and DODAB are by far the most investigated from this series. The dependence of T-m of these surfactants on the number n of carbons in the surfactant tails is reported. The T-m obtained by DSC increases non-linearly with n, and the vesicle apparent radius R-h is about the same for DHDAB and DODAB, but much smaller for DDAB. (c) 2006 Elsevier B.V.. All rights reserved.
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dialkyldimethylammonium salts, Cationic vesicle, cationic surfactants, DODAB, DHDAB, DTDAB, DDAB, phase behavior, differential scanning calorimetry, dynamic light scattering, melting temperature, hydrodynamic radius
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Inglês
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Chemistry and Physics of Lipids. Clare: Elsevier B.V., v. 142, n. 1-2, p. 128-132, 2006.
