ABSTRACTThe electrophilic substitution of regioregular poly(3-hexylthiophene) (P3HT) at the 4- position was investigated to produce structurally well defined 3,4-disubstituted poly(thiophene)s. When P3HT was treated with N-bromosuccinimide (NBS) in chloroform at 25 to 50 °C, the 4-hydrogen atom in P3HT is completely substituted by bromine, as indicated by the 1H NMR, 13C NMR and elemental analysis. Similarly, the chlorinated product was obtained using N- chlorosuccinimide (NCS) at room temperature. However, only 85% of the 4-hydrogen atoms were replaced by chlorine and ∼15% of the α-hydrogen atoms on the hexyl side chain were chlorinated. P3HT readily reacts with fuming nitric acid in chloroform at 0 °C to generate a nitrated product with almost 100% substitution at the 4-position. Our preliminary study on the futher functionalizaton of these polymers was conducted on the brominated product. Our results showed that the bromine atom in this polymer could be further substituted with other groups.
