A novel monomer bearing with pyrazoline chromophore, 3-(4-fluorophenyl)-1-phenyl-5-(4-(4-vinylbenzyloxy)phenyl-4,5-dihydro-1H-pyrazole (FStODO), was synthesized, and its atom transfer radical polymerization initiated by a tetrafunctional initiator, pentaerythritol tetrakis(2-bromoisobutyrate) (4Bri-Bu), was studied in detail and characterized by 1H NMR, GPC, and TG-DSC. The solution, film luminescence of monomer, and its polymer were studied in detail. Compared with that of monomer, both luminescence emission intensity and quantum yield of star-shaped polymer PFStODO in DMF solution are decreased. However, the two-photon absorption (TPA) spectra in DMF solution measured by a femtosecond laser show an entirely different result that the maxima TPA cross-section value of polymer reaches to 203 GM, better than that of the monomer itself (13 GM). More interestingly, the film of polymer shows surprisingly white emission ranging from 400 to 700 nm assigned to the excimer formation. We attribute this formation of excimers to the ordered chromophore aggregates in film, which is further verified by X-ray diffraction. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 50: 480-487, 2012