A PEO-PPO-PEO block copolymer, Pluronic P123, was reacted with phosphorus oxychloride for the synthesis of phosphorylation substitution of Pluronic P 123 (PS-P 123). A novel multilayer film composed of PS-P 123 micelles was fabricated by alternating deposition of the negatively charged polymer micelles and positively charged polyethylenimine (PEI). Pyrene as a model hydrophobic organic molecule was loaded into the PS-P123 micelles. The PEI/PS-P123 multilayer films have temperature dependent solubilization property due to the formation of more hydrophobic microenvironment at higher immersed solution temperature. The reversible loading and release of pyrene by the multilayer films was also observed. The PEI/PS-P123 multilayer films have potential use in controlled drug release, extraction, and other technical use. (c) 2006 Elsevier Ltd. All righs reserved.