A novel copolymer has been prepared by free radical polymerization in dimethylformamide of 5-dimethylamino-1-(beta-methacryloyloxyethylcarbamoyloxyethyl)-N-methyls ulfonamido-naphthalene (Dns-Acr) and methyl methacrylate in 1:3 M ratio with azobis(isobutyronitrile) as the initiator. The structure, purity, and the chemical composition of the dansylated copolymer (Dns-COPA) were confirmed by spectrophotometric ((HNMR)-H-1, FTIR, UV/vis), thermal and analytical methods, GPC measurements, and AFM techniques. Compared with Dns-Acr, whose fluorescence emission band appears at 510 and 430 nm (shoulder), the photoluminescence spectrum of the Dns-COPA in DMF solution exhibited a strong fluorescence emission at 440 nm (I-1), and a small shoulder at 520 nm (I-2) accompanying the main signal. The emitting behavior of Dns-COPA was investigated through a spectrofluorimetric titration experiment, the fluorescence measurements demonstrating that introduction of various acids into the solution has a significant effect upon the quenching of fluorescence. This ability of dansyl copolymer to suffer the protonation of the amino group in organic acidic phase may be exploited in sensor applications. (C) 2008 Wiley Periodicals, Inc.