Synthesis and Characterization of Polythiophene Derivatives with Different Alkyl Substitution Groups

Three kinds of poly (3-alkylthiophene), such as poly (3-butylthiophene) (P3BT), poly (3-hexylthiophene) (P3HT) and poly (3-dodecylthiophene) (P3DDT) were prepared by the Grignard Metathesis Method (GRIM). Their chemical structures are characterized by FTIR, 1H-NMR and GPC. 1H-NMR result shows that regioregular structure of these polymers is relatively higher. The GPC results show that the molecular weight of the polymers is 8.42×104, 1.06×105 and 1.21×104 g/mol with molecular weight distributions of 1.41, 2.18 and 1.18, respectively. The DSC result shows that the glass transition temperature of three kinds of polymers is 120.8, 146, 118 °C, respectively. UV absorption spectrum and fluorescence spectroscopy of three polymers in THF solution show that the maximum absorption wavelength is 448 nm, 470 nm, 390 nm, and the maximum emission wavelength is 531, 535, 527 nm with the band gap of 2.06, 1.86, 2.21 eV, respectively.