화학공학소재연구정보센터
Journal of Chemical and Engineering Data, Vol.56, No.5, 2647-2654, 2011
Formation and Growth of Gemini Surfactant (12-s-12) Micelles as a Modulate by Spacers: A Thermodynamic and Small-Angle Neutron Scattering (SANS) Study
A series of symmetrical cationic gemini surfactants of the type N,N'-didodecyl-N,N,N',N-tetramethylalkane-alpha, omega-diammonium dibromide "12-s-12" (s = 2, 4, 6, 8, 10, and 12) are synthesized, and their micellization study in aqueous solution is systematically reported. Specific conductivity as a function of surfactant concentration was measured, and critical micelle concentration (CMC), degree of counterion dissociation (a) of the micelle, and thermodynamic parameters, namely, Gibbs energy (Delta G(m)), enthalpy (Delta H(m)), and entropy (Delta S(m)), of micellization were evaluated using this data at various temperatures. Surface tension studies at 298.15 K provided similar CMCs as given by conductometry along with information on the efficiency/effectiveness and the area occupied per molecule. Small-angle neutron scattering (SANS) inferred the presence of few morphological geometries ranging from spherical to rodlike micelles. Results are explained in terms of the hydrophobicity of spacer chain length along with the electrostatic repulsion between the cationic centers of gemini surfactant molecules.