Effect of iron-iron oxide particles on the rate of isomerization of azobenzene moieties in polymeric liquid crystals at air-water interface

We have studied the effect of iron-iron oxide particles on the trans-cis isomerization of azobenzene moieties in the novel polyethylene glycol itaconate-azobenzene based side chain liquid crystalline polymer (PEGIA). Langmuir monolayers of the PEGIA molecules are spread at air-water interface, with water subphase containing different concentrations of iron-iron oxide particles. The kinetics of the isomerization of azobenzene moieties in the polymer was studied by surface manometry technique. We find that the presence of iron-iron oxide particles in the subphase affects the rate constant of trans-cis photoisomerization and it decreases exponentially as a function of concentration of particles in the subphase. The critical concentration of iron-iron oxide particles above which the rate constant of photoisomerization negligibly changed was found to be about 2.468 μg cm− 3.