High refractive index polymer films have been extensively investigated because of their wide application potentials. We now designed thiophene-containing polystyrene as colorless and transparent high-refractive-index thin film. The copolystyrenes were synthesized by general radical polymerization with controlled mole ratios 0 : 10, 1 : 9, 3 : 7, 5 : 5, 7 : 3, 9 : 1, 10 : 0 (styrene : p-bromostyrene), respectively. Next, the thiophene-containing polystyrenes were synthesized by Suzuki-Miyaura coupling reaction. The chemical structures of synthesized thiophene-containing polystyrene in accordance with ratios were confirmed by using H-1-NMR, C-13-NMR, and FTIR. The effect of the thiophene units on refractive index according to copolymer ratios were confirmed by using prism coupler. The thiophene-containing polystyrene showed improved refractive index ranging from 1.58 to 1.67 and birefringence in the range of 0.0001-0.0019. The thermal stability and thermal behaviors of thiophene-containing polystyrene also can be confirmed by TGA and DSC. The polymers have high glass transition temperature in the range of 108 degrees C-177 degrees C. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012