Near-field scanning optical microscopy studies of a fluorescent polyelectrolyte-surfactant complex

Thin films prepared from a complex formed between poly(vinyl sulfate) (PVS) and a cationic indocarbocyanine surfactant dye (DiI) are investigated by n ear-field scanning optical microscopy (NSOM) and atomic force microscopy (A FM). Local film morphology and chemical composition are studied as a functi on of dye/anionic-site stoichiometry. AFM images show that overall film mor phology changes modestly with dye content. Fluorescence NSOM images reveal that at lowest PVS loading, the films are extremely heterogeneous, exhibiti ng round fluorescent regions 100-250 nm in size. As the dye content is incr eased, the fluorescent regions increase in number but remain of similar siz es. NSOM fluorescence spectra prove these regions contain aggregated DiI an d indicate they are likely polymer- surfactant micelles entrapped in the fi lms.