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 surfactants having varied hydrophobic chains, [(2-alkyl-1,3-dioxolan-4-yl)methyl]trimethylammonium bromides (C n -D-TAB; where C n = C 9 H 19, C 11 H 23, C 13 H 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 °C. The aggregation parameters (translational diffusion coefficient of micelle ( D 0 ), hydrodynamic radius ( R h ), ionization fraction (α), and aggregation number (n)) have been determined and discussed with respect to the parameters of the “classical” alkyltrimethylammonium bromides (C n -TAB). Additionally, the effect of diastereoisomerism upon surfactant aggregation has been characterized for the trans- and cis -[(2-tridecyl-1,3-dioxolan-4-yl)methyl]trimethylammonium (C 13 -D-TAB), (2-hydroxyethyl)dimethylammonium (C 13 -D-HEAB), and triethylammonium (C 13 -D-TEAB) bromides. Accordingly, the 1,3-dioxolane ring configurations and the size of the head groups do not involve noticeable diastereomeric 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 characteristics.