Characterization of Vesicle and Microemulsion Microstructures
Abstract
A major focus of our research has been on the development of techniques that permit direct visualization of surfactant microstructures. With complex microstructures like vesicles, liposomes or microtubules, where polydispersities and interactions are important issues, the abilities to directly observe real time behavior and structural details is important in characterizing amphiphilic systems. We have employed two techniques, video enhanced microscopy (VEM) and cryo-transmission electron microscopy (cryo-TEM). We have been interested in characterizing surfactant aggregates in water as a function of temperature. The original stimulus for this work was the desire to understand how the unique structural properties of water affected self-assembly processes. Specifically the goal was to determine whether nonpolar groups are driven out of aqueous solution by the release of structured water (entropic effects), and that water is therefore different from all other solvents. We studied micellization across a sufficiently large temperature range (25 to 160 C) so that water changed from a highly structured liquid to just another polar hydrogen bonded solvent. We have shown that changing surfactant counterions can have a dramatic effect on aggregate structure. The key observation was that double-chained cationic surfactants like dido-decyldimethylammonium form clear nonviscous solutions with acetate or hydroxide counterions up to quite high concentrations (C = 0.2 M). The corresponding bromides are opaque, liquid crystalline dispersions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1988
- Accession Number
- ADA201381
Entities
People
- D. F. Evans
Organizations
- University of Minnesota