Abstract: Excimer fluorescence was used to probe the change of fluorescence intensity ratio of excimer/monomer chromophore I_E/I_M of poly(S-b-MMA)with concentration in THF solution. Three concentration regions are recognized in the range studied with respect to the values of I_E/I_M. In region Ⅰ, the values of I_E/I_M are independent of the concentration of the solution. In region Ⅱ, the I_E/I_M values increase with the increase of concentration. In region Ⅲ, the values of I_E/I_M almost keep constant. This phenomenon is attributed to the shrinkage of polymer coils and the entanglement of polymer chains at high concentration. The formation of micelles of the block copolymer in THF solution on addition of acetone was also studied. The change of I_E/I_M values indicates that the PS chains act as core and the PMMA chains as the corona.

Key words: poly(styrene-b-methyl methacrylate), fluorescence, excimer, micelle