Investigation on the behavior of choline-derived cationic surfactant in aqueous solution in the absence and presence of PdCl2

A choline-derived cationic surfactant dodecyl-(2-hydroxyethyl)-dimethylammonium bromide (DHDAB) was synthesized. The properties of DHDAB and DHDAB/PdCl2 aqueous solutions were investigated by employing tensiometry, conductance, dynamic light scattering, transmission electron microscopy and turbidity measurements. The fraction of counterion binding (β) of the DHDAB micelle decreases with increase of the temperature. The energetics of the self-assembly process of DHDAB were evaluated, it indicated the Δ H m 0 and Δ S m 0 values for the micellization exhibited nice compensations between them. Addition of PdCl2 to the DHDAB solutions can significantly affect the interface and aggregation properties of DHDAB solutions due to forming a complex between DHDA+ and [PdClmBr4−m]2−. The phase behaviors of the DHDAB/PdCl2 aqueous mixture at fixed ratios and at constant concentration of PdCl2 were studied. DLS coupled with TEM studies indicated the DHDAB/PdCl2 aqueous mixtures can form vesicles in a certain CDHDAB range. Moreover, the hollow Pd spheres were obtained by direct reduction (with NaBH4) of the DHDAB/PdCl2 aqueous mixture at the control experimental condition. This may advance further understanding of metal-ion induced transformation of organized assemblies in choline-like cationic surfactant solutions and promote its applications in preparation of hollow nanomaterial.