Salt effect on the interactions between gemini surfactant and oppositely charged polyelectrolyte in aqueous solution

Yingying Pi; Yazhuo Shang; Honglai Liu; Ying Hu; Jianwen Jiang

doi:10.1016/j.jcis.2006.10.020

Salt effect on the interactions between gemini surfactant and oppositely charged polyelectrolyte in aqueous solution

J Colloid Interface Sci. 2007 Feb 15;306(2):405-10. doi: 10.1016/j.jcis.2006.10.020. Epub 2006 Nov 20.

Authors

Yingying Pi¹, Yazhuo Shang, Honglai Liu, Ying Hu, Jianwen Jiang

Affiliation

¹ Lab for Advanced Materials and Department of Chemistry, East China University of Science and Technology, Shanghai 200237, China.

PMID: 17113593
DOI: 10.1016/j.jcis.2006.10.020

Abstract

The effect of alkali halides (NaBr, NaCl, KCl) on the interactions between the cationic gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and the anionic polyelectrolyte sodium polyacrylate (NaPAA) in aqueous solution has been investigated by fluorescence emission spectroscopy, UV transmittance, zeta potential, and transmission electron microscopy (TEM). With increased addition of NaBr, a counterbalancing salt effect on the critical aggregation concentration (CAC) is observed. At low concentrations, NaBr facilitates the formation of micelle-like structures between surfactant and polyelectrolyte and results in a smaller CAC. At high concentrations, NaBr screens the electrostatic attraction between surfactant and polyelectrolyte and leads to a larger CAC. Upon the formation of micelle-like structures at high surfactant concentrations, the addition of NaBr is favorable for larger aggregates. The microstructure detected by TEM show that a global structure is generally formed in the presence of NaBr. The interactions also depend on ion species. Compared to NaBr, the addition of NaCl or KCl yields a smaller CAC.