Polymer Micelles as Building Blocks for Layer-by-Layer Assembly:  An Approach for Incorporation and Controlled Release of Water-Insoluble Dyes

We describe the use of block copolymer micelles as building blocks for incorporation of water-insoluble dyes and then fabricate multilayer films by alternating deposition of the polymer micelles of poly(styrene-b-acrylic acid) and poly(diallyl-dimethylammonium chloride) (PDDA). Pyrene, a small organic molecule that is difficult to assemble by the usual methods, was incorporated into the micelles and then assembled into multilayer film. The growth procedure of the multilayer films was monitored by UV−vis and fluorescence spectroscopies, and the results revealed that the multilayer films grew in a uniform way in every deposition cycle. In-situ and ex-situ atomic force microscopy (AFM) images proved the existence of block copolymer micelles in LbL films. Furthermore, pyrene molecules assembled can be released from the multilayer films by immersing the films into solutions of different ionic strength. Micelles with different core−shell structures exhibited different release rates of pyrene. These films have potential use as controlled assembly and release materials for some water-insoluble dyes.