The DR-PPA polyelectrolyte complex was formed via the interaction of diazoresin(DR) and polyphosphoric acid(PPA) in aqueous solution The DR-PPA complex does not dissolve in water but dissolves considerably in sodium dodecyl sulfate(SDS)aqueous solution．The solubility of DR-PPA in 0.05．0.10

0.15 mol／L SDS aqueous solution(100 mL) was determined at 20℃ to be 0.25

1.10 and 1.80 grespectively The DR-PPA／SDS film on a substrate(modified PET film or anodized AI plate) is photosensitive and can produce an image under the exposure of UV light through a photographic film．The Dhotodecomposition of DR-PPA in 0.15 mol／L SDS aqueous solution or in its solid film was carried OUt and confirmed to be．both in solution and in film

in accordance with the first order reaction in kinetics An ultra-thin multilayer film from DR and PPA has been prepared by self-assembly technique．It was verified that the self-assembly process progresses smoothly with an absorbance increasing of ～0.02 per DR-PPA layer at 370 am．The multilayer film is also photosensitive and its decomposition is also in agreement well with first order reaction．Under UV irradiation the ionic bond both in the coating and in self-assembly films converts to covalent bond．As a result the dissolution behavior of the DR-PPA film changes dramatically i.e. from soluble in SDS aqueous solution to insoluble because the crosslinking nature of the film changes from ionicbefore irradiation to covalent after irradiation．