Journal of Physical Chemistry B, Vol.101, No.6, 871-875, 1997
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 = C9H19, C11H23, C13H27), 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 coefficient of micelle (D-0), hydrodynamic radius (R(h)), ionization fraction (alpha), 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 (C13D-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.
Keywords:DYNAMIC LIGHT-SCATTERING;SODIUM DODECYL-SULFATE;CHEMODEGRADABLE SURFACTANTS;INTERMICELLAR INTERACTIONS;DESTRUCTIBLE SURFACTANTS;CLEAVABLE SURFACTANTS;FRACTIONAL IONIZATION;AQUEOUS-SOLUTION;HYDROLYSIS;SYSTEMS