THE USE OF EPR SPECTROSCOPY UNDER NON-AMBIENT CONDITIONS TO CHARACTERIZE THE CONSEQUENCES OF CLATHRATE HYDRATE FORMATION IN WATER-IN-OIL MICROEMULSIONS

Electron paramagnetic resonance (EPR) spectroscopy is used to characte rize the aqueous environment of water-in-oil microemulsion droplets at low temperatures and in the presence of a gas phase at enhanced press ures. The conditions are chosen to induce clathrate hydrate formation in the water droplets. A water soluble nitroxide radical, 4-hydroxy-TE MPO, incorporated into the core of the microdroplets acts as the repor ter group. The tumbling rate of the spin probe decreases and the polar ity of the spin probe environment increases as the temperature is lowe red. Under hydrate formation conditions, it is seen that the probe mot ion in a small droplet is more rapid than motion in a larger droplet. This is due to the spin probe being rigidly fixed in the microdroplets at low temperature, following the droplet tumbling rate. Also, the po larity of the spin probe environment decreases significantly upon gas hydrate formation due to the depletion of water from the microdroplet core in the form of a solid gas hydrate phase.