Aggregation number of alkanediyl-α,ω-bis(dimethylalkylammonium bromide) surfactants determined by static light scattering

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2000-10, Vol.172 (1), p.139-144
• Main Authors: Pisárčik, Martin, Devı́nsky, Ferdinand, Lacko, Ivan
• Format: Article
• Language: English
• Subjects: Aggregation number; Dimeric surfactant; Micelles; Static light scattering
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/S0927-7757(00)00589-6

Aggregation number of alkanediyl-α,ω-bis(dimethylalkylammonium bromide) surfactants in aqueous solutions has been determined at different number of carbon atoms in the alkyl tail ‘ m’ and in spacer ‘ s’ by using static light scattering. Values of aggregation number at different spacer numbers s=2–10 lie between 17 and 33 and between 18 and 55 for alkyl tail lengths m=9–16, respectively. Data for variable parameter s correspond to results obtained by neutron scattering technique. In all cases but s=2 and m=16, the slopes of Debye plots were found to be increasing and the value of the second virial coefficient B was found to be in the range 1.3×10 −3–13×10 −3 cm 3 mol g −2 indicating the spherical shape of micelles. Increased aggregation number and negative B of surfactant with the shortest spacer s=2 indicates the rod-like micelle shape. Aggregation number of surfactant with the longest alkyl tail m=16 is too small to predict the rod-like shape of the micelle.