| Abstract: | To regulate the pH value of an aqueous solution containing polyelectrolyte by photoirradiation, an azoaromatic poly(carboxylic acid), acrylic acid(AA)-p-phenylazoacrylanilide (PAAn) copolymer was synthesized and the photoresponse of the polymer solution was investigated. AA-PAAn copolymer, which takes a compact form in the ordinary state owing to the presence of azoaromatic side chains, is transformed into an extended form when azoaromatic moieties are isomerized by photoirradiation. Thus, the pH value of the solution can be reversible regulated by irradiation and interruption of light through a change in polymer conformation. The range of the pH change was about 0.15. These phenomena can be explained on the basis of polarity change induced by the photoisomerization of azoaromatic side chains. |
