Two electroactive polystyrene derivatives para-substituted with pi-conjugated oligothiophene, poly(5-hexyl-5 ''-(4-vinylphenyl)-2,2':5',2 ''-terthiophene) (PH3TS), and poly(5-hexyl-5 ''''-(4-vinylphenyl)-2,2':5',2 '':5 '',2''':5''',2 ''''-quinquethiophene) (PH5TS) have been successfully synthesized via the Stille coupling reaction between tributyltin postfunctionalized poly(4-(2-thiophenyl)styrene) (PTS) and bromo-oligothiophene. The effect of the chain length of the pendant oligothiophenes on properties of the resulting polymers including solubility, thermal stability, optical absorption, and electroactivation energy levels has been studied by using a variety of techniques such as thermogravimetric analyzer, differential scanning calorimetry, UV-Vis, Fluorescence, and cyclic voltammetry. With shielding of the hexyl terminal groups attached to the pendant oligothiophene units, no obvious chain aggregation was observed for both PH3TS and PH5TS even in a poor solvent environment. When compared with conventional linear conjugated polymer systems, the concept of grafting electroactive units as pendant side chains via postfunctionalizing aliphatic polymers might offer a strategy to precisely synthesize new electroactive polymer materials for a number of organic electronic applications. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 1155-1162, 2011