PHOTO-REVERSIBLE REACTION IN POLYMER LANGMUIR-BLODGETT-FILMS

Preparation of photoreactive Langmuir-Blodgett (LB) films was carried out using polymers/oligomers prepared from long-chain dialkyl esters of di- and tetra-olefins and having cyclobutane rings in the main chain. These polymers/oligomers formed stable monolayers on a water surface when mixed with arachidic acid. These monolayers could be deposited onto a substrate successfully forming Y-type films. The oligomer LB films were polymerized on irradiation. The polymer LB films showed a photo-reversible process between polymers and oligomers, depending on wavelength of the irradiating light. On the basis of spectral data and molecular weight change, this behaviour was found to be caused by cleavage and formation of cyclobutane rings.