Methyl, butyl, and octadecyl methacrylate copolymers with 3-methacrylo-ylamino-2-naphthoic acid (MANA) carrying alkali counterions exhibit two emission bands in highly dilute dioxane, heptane, and toluene solutions. One band (alpha) has a maximum around 400 nm, and the other (beta) has a maximum around 500 nm. The ratio of the intensity of the a band to the intensity of the beta band depends on the counterion (Na+, Li+, and Cs+) and the solvent. Varying the MANA content of the copolymer with Na+ counterions increases the relative intensity of the a emission in proportion to the density of MANA residues in the ionomer chain, whereas in chains containing only 0.1% MANA residues, only a beta emission can be seen. The alpha emission is due to associated ion pairs, and the beta emission is due to unassociated. ion pairs. The shorter the alkyl chain pendant is of the copolymer, the larger the fraction is of the associated ion pairs. The half-bandwidth of the beta emission is much larger than that of the alpha-emission band in all cases. The half-bandwidth decreases in the order Li+ > Na+ > Cs+. The fluorescence anisotropy decays for the alpha- and beta-emission bands are double-exponential. The longer rotational correlation time and its fractional contribution to the beta emission increase with an increasing content of the MANA monomer in the copolymer. The decay anisotropy data are consistent with the shell-core model of ionomers in nonpolar solvents. The fluorescence anisotropy decay of the copolymer of butyl methacrylate with a low content of the nonneutralized MANA (similar to 0.1 mol %) is single-exponential, and the rotational correlation time of the MANA fluorophore is eight times longer than that of 3-acetyl-2-naphthoic acid methyl ester (0.3 ns) in the same solvent. (C) 2004 Wiley Periodicals, Inc.