Isothermal switching of conductivity in microemulsions via photodimerization of acridizinium bromide

Microemulsions composed of Aerosol OT (AOT), isooctane, and water in the mass ratio 1:1.54:0.75 exhibit percolation, i.e., transition from a w/o to an o/w microemulsion, at 33 degrees C as revealed by the appearance of conductivity. In the presence of 0.01 mol/dm(3) of acridizinium bromide the percolation temperature increases to 38 degrees C. Irradiation of this mixture with glass-filtered light leads to a further rise of the percolation temperature to 43 degrees C. Thus, the system can be switched from conducting to non-conducting upon irradiation at between 38 and 43 degrees C.