Synthesis and aggregation behaviors of disulfonate gemini surfactant with double hexadecyl tails

Dihexadecyl diphenyl ether disulfonate (C-16-DADS) was synthesized via three-step reactions: Friedel-Crafts alkylation, sulfonation and neutralization. H-1 NMR and ESI-MS were used to characterize the structure of target products. The aggregation behaviors of C-16-DADS in aqueous solutions were investigated by electrical conductivity, steady state fluorescence, dynamic light scattering, transmission electron microscopy and rheological measurements. The results show that spherical micelles, wormlike micelles, wormlike micellar gels and network of branched worms are formed with increasing the surfactant concentration. The electrical conductivity data show that C-16-DADS possess a relatively low critical micelle concentration (0.105 mM, 30 degrees C) and the micellization process is primarily driven by the entropy. Transmission electron microscopy images demonstrate the existence of spherical micelles in C-16-DADS solutions with 0.8 mM and 2 mM surfactant concentrations. The average aggregation number values of C-16-DADS are low because of the formation of premicellar aggregates. Wormlike micelles formed by C-16-DADS without additive are proved by rheological experiments, particularly fascinating is the formation of wormlike micellar gels and network of branched worms with the increase of C-16-DADS concentration. (C) 2016 Elsevier B.V. All rights reserved.