Steady-state and time-resolved fluorescence studies of reverse micelles in liquids and supercritical solvents

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7046052

Zhang, Jing

The authors investigate the effects of temperature, salt concentration, and water loading on the internal dynamics of AOT Aerosol-OT, sodium bis (2-ethylhexyl sulfosuccinate) micelles in liquid heptane, using ANS-like (anilino-naphthalene sulfate) fluorescent probes. The important results from these experiments are that: (1) the molecular geometry of the probe is the predominant factor controlling partitioning even at high water loadings; (2) the photophysics of ANS is strongly dependent on the water content and temperature and corresponds to changes in local polarity and viscosity; (3) addition of electrolytes changes the dynamic fluorescence which is in turn related to the changes in internal microenvironments; and (4) a nanosecond solvent relaxation process occurs within reverse micelles. It was wondered if the continuous phase (alkane) density could be used to control the internal dynamics within a reverse micelle. To answer this question, research focused on: (1) the effects of water loading, temperature, and fluid density on solute partitioning and determination of the density effects on micellar aggregates; (2) the effects of solute structure on the distribution of probe molecules within reverse micelles; and (3) the effects of fluid density, water concentration, and temperature on the reorganizational dynamics within AOT reverse micelles. Simple thermodynamic measurements and nanosecond solvent relaxation experiments are used to account for this partitioning and water reorganization in AOT reverse micelles, respectively. Results on excited-state deprotonation reactions in AOT reverse micelles maintained in sub-critical propane, provides a useful model for density-controlled deprotonation reactions within reverse micelles. Preliminary work shows that the continuous phase density can be used to control reactions within reverse micelles formed in near- and supercritical alkanes.

• Research Organization: State Univ. of New York, Buffalo, NY (United States)
• OSTI ID: 7046052
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CHARGED-PARTICLE TRANSPORT
CHEMICAL REACTIONS
DYNAMICS
EMISSION SPECTROSCOPY
FLUORESCENCE SPECTROSCOPY
MECHANICS
MICELLAR SYSTEMS
MOLECULAR STRUCTURE
PROTON TRANSPORT
RADIATION TRANSPORT
SPECTROSCOPY
SUPERCRITICAL STATE