Polystyrene doped with mixed rare earth triisobutoxide has been prepared by in-situ bulk polymerization. The modified polystyrene (PS) has been characterized by FT-IR

UV-Vis

fluorescence spectra (FS)

dynamical mechanical thermal anaylsis(DMTA) and the impact strength of PS materials was determined before and after the modification．The results showed that coordination interaction exists between rare earth ion with phenyl in the modified PS. The modified PS materials are soluble in common organic solvents

such as benzene、chloroform、tetrahydrofuran and N

N-dimethylformamide

which make them useful for forming films．Indicated by FS

the fluorescence strength of the modified PS is higher than that of pure PS．By the DMTA curves of PS materials

it is indicated that the glass transition temperature(Tg) of the modified PS decreases with increasing rare earth content and there is a broad β-transition peak at -70℃．Moreover

the peak of loss modulus at low temperature and the impact strength are enhanced considerably．Therefore it can be concluded that the mixing of rare earth triisobutoxide has good toughening effect for polystyrene．