Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observedwith fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB)

dodecyltrimethylammonium chloride (DTAC)

and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) wereallowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalenelabeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride(PyMeAHCl) and the non-radiative energy transfer(NRET)Ipy/INp of naphthalene to pyrene for labeled polyelectrolytes were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes.The 1:1aggregation of polyelectrolyte-CTAB with respect to the change was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC).The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails.However

neither 1:1 polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail

which is shorter than that of CTAB.As known from the fluorescence results

nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes

but the presence of PAMPS promoted the micelle fromation for C12E8 at the CAC slightly below its critical micelle concentration(CMC).The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant.SAXS suggested a lamella structure for the AMPS copolymer-surfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC

respectively.