Effects of light intensity on the photoinduced potential changes across poly(vinyl chloride) (PVC) membrane entrapping a photoresponsive crown ether 4, 4'-bis[3, 4-(l, 4, 7,10,13-penta-oxatridecane-1,13-diyl)benzyloxycarbonyl]azobenzene  have been discussed. The photochemical isomerization reaction of  in the membrane proceeded rapidly when the membrane was exposed to higher intensity ultraviolet (UV) light, while longer time was required for attaining the photostationary state under weaker intensity light (Fig. 3). The intensity of UV light as well as the membrane thickness affected the cis- content in the photostationary-state mixture of the irradiated  in the membranes (Table. 1). The magnitude of the potential change was appreciably influenced by the light intensity. The irradiation with higher intensity light resulted in the large potential shift, but the potential shift was small when the light intensity was low (Tables. 2 and 3, Figs. 5, 6 and 7). This trend of light-intensity dependence was significantly observed for thicker membranes, presumably because of the enhanced difference in cis- content between the opposite surfaces of the thick membranes. These observations support that the photoinduced potential changes stem from the surface potential changes originating from the perturbation in charge density of the membrane surfaces.
ASJC Scopus subject areas
- Chemical Engineering(all)