MICELLAR AGGREGATION BEHAVIOR AT LOW IONIC-STRENGTH OF CYCLIC ACETAL-TYPE CATIONIC SURFACTANTS CONTAINING THE 1,3-DIOXOLANE MOIETY

Aggregation studies in water of several cationic acetal-type surfactan ts having varied hydrophobic chains, 2-alkyl-1,3-dioxolan-4-yl)methyl] trimethylammonium bromides (C-n-D-TAB; where C-n = C9H19, C11H23, C13H 27), have been performed by means of dynamic light scattering in the 0 .015-0.32 M NaBr concentration range over the temperature limits of 25 -45 degrees C. The aggregation parameters (translational diffusion coe fficient of micelle (D-0), hydrodynamic radius (R(h)), ionization frac tion (alpha), and aggregation number (n)) have been determined and dis cussed with respect to the parameters of the ''classical'' alkyltrimet hylammonium bromides (C-n-TAB). Additionally, the effect of diastereoi somerism upon surfactant aggregation has been characterized for the tr ans- and ridecyl-1,3-dioxolan-4-yl)methyl]trimethylammonium (C-13-D-TA B), (2-hydroxyethyl)dimethylammonium (C13D-HEAB), and triethylammonium (C-13-D-TEAB) bromides. Accordingly, the 1,3-dioxolane ring configura tions and the size of the head groups do not involve noticeable diaste reomeric discrimination in the self-assembling abilities. Because the studied cationic acetal-type surfactants contain a 1,3-dioxolane unit (D), they are an acid hydrolyzable type of chemodegradable surfactant, which is analogous to C-n-TAB in terms of the micellar aggregation ch aracteristics.