Switching electrical conductivity in an AOT-isooctane-water microemulsion through photodimerization of solubilized N-methyl-2-quinolone.
The electrical conductivity of microemulsions composed of Aerosol OT (AOT), isooctane and water as a function of temperature was studied in the absence and presence of N-methyl-2-quinolone (NMQ), and consequences of an in situ photodimerization of NMQ were investigated. A conductivity increase upon raising the temperature of a water-in-oil microemulsion indicates percolation. Percolation temperatures (Tp) can be influenced specifically by the addition of certain substances. Small amounts of solubilized N-methyl-2-quinolone induce lower Tp (by up to 9 K), and photodimerization of NMQ shifts Tp back to higher values. Consequently, the microemulsion can be switched from conducting to non-conducting without varying temperature or composition by exposing samples to UV light at lambda > 310 nm. The effect can be reverted in part by irradiation at lambda = 250 nm. Coumarin derivatives--structurally related to NMQ--show much slighter effects.
Bufe
Markus
M
Technische Universität Dresden, Physikalische Chemie, Professur für Grenzflächen- und Kolloidchemie, D-01062 Dresden, Germany.
Wolff
Thomas
T
D019281:Dimerization; D004143:Dioctyl Sulfosuccinic Acid / Q000737:chemistry*; D004553:Electric Conductivity; D004655:Emulsions / Q000737:chemistry; D009795:Octanes / Q000737:chemistry*; D010777:Photochemistry / Q000379:methods*; D015363:Quinolones / Q000737:chemistry*; D012995:Solubility; D012996:Solutions; D014867:Water / Q000737:chemistry*
D004655:Emulsions; D009795:Octanes; D015363:Quinolones; D012996:Solutions; D014867:Water; D004143:Dioctyl Sulfosuccinic Acid; C045798:2,2,4-trimethylpentane