Vesicles and Nanofibers with Krafft Transition from Cationic Surfactant-Divalent Azobenzene Dye Salt-Free Complex

Abstract

An unusual thermo-reversible sol-gel transition was found in the salt-free complex of cetyltrimethylammonium bromide and disodium 4, 4′-azobenzene dicarboxylate around the Krafft temperature. The combined investigation by dynamic light scattering, polarized microscopy, atomic force microscopy, cryogenic transmission electron microscopy, and small angle x-ray scattering revealed that vesicles were formed in the aqueous solution at 50°C, and nanofibers composed of two-dimensional hexagonal array of cylindrical micelles in the gel state at 25°C.

Keywords:

• Disodium 4,4′-azobenzene dicarboxylate
• cetyltrimethylammonium bromide
• nanofibers
• sol-gel transition
• vesicles

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (NSFC 20803053 and 20973129). The authors are grateful to Prof. Qinfen Zhang of Zhongshan University for the kindly help with the cryo-TEM measurements.