Aggregate Conformation and Rheological Properties of Didodecyldimethylammonium Bromide in Aqueous Solution

Abstract

Aggregation behavior of didodecyldimethylammonium bromide (DDAB) in aqueous solution was investigated using negative-staining and freeze-fracture transmission electron microscopy (TEM) methods. With the concentration increase, the vesicle size enlarged from the range of 100–200 nm to 500–3000 nm and the structure transform from unilamella to multilamella. Rheological and viscosity measurement results indicated that the system exhibited a gel-like material characteristic and shearing thinning in property, as shown that the apparent viscosity decreased gradually during the shear rate ascended from 1 × 10⁻⁴–1 × 10⁴ s⁻¹. Furthermore, the relationship between aggregate conformation and solution rheological properties was discussed.

Keywords:

• Aggregate conformation
• didodecyldimethylammonium bromide
• giant vesicle
• rheological property

Acknowledgments

The authors acknowledge the financial support of the National High Technology Research and Development Program of China, Grant No. 2006AA09Z305 and 2007AA090701-2.