PREPARATION OF POLYMER LANGMUIR-BLODGETT-FILMS CONTAINING PYRENE CHROMOPHORE AND ENERGY-TRANSFER IN THE FILMS

Pyrene chromophore could be introduced into polymer Langmuir-Blodgett (LB) films in the form of copolymers of N-(1-pyrene)acrylamide (PyA) and N-alkylacrylamides (AA) which have an excellent ability to form stable monolayers and LB multilayers. The spreading behaviors of the copolymers of PyA with AA having various alkyl chain lengths (octyl (OA), decyl (DA), dodecyl (DDA), and tetradecyl (TDA)) on a water surface were investigated by a measurement of the surface pressure-surface area isotherms. The isotherms show that N-dodecylacrylamide copolymers (P(DDA/PyA)) form the most stable condensed monolayers, and the pyrene chromophore is dispersed uniformly having its own surface area on the water surface. All the copolymer monolayers of PyA with AA could be transferred onto solid supports as a Y-type film. Regular and uniform deposition was confirmed by a linear relationship between the UV absorbance of the pyrene chromophore and the number of layers. The excimer formation and energy transfer of the pyrene chromophore in the LB films have been investigated by photostationary fluorescence spectroscopy. In the copolymer LB films of OA, the relative intensity ratio of the excimer emission to the monomer (I(e)/I(m)) increases with the number of layers, whereas the ratio in the LB films of DA and DDA was not changed with the numbers. The vertical energy transfer efficiency is discussed from a comparison of the alkyl chain length (thickness of monolayer) with energy transfer critical distance.