Spectroscopic study of the microstructure and phase transition of regioregular poly(3-dodecylthiophene)

Abstract

Regioregular poly(3-dodecylthiophene) (P3DDT) films were studied by temperature-dependent FTIR and DSC. Structural evidence was presented to confirm that the endothermic transition observed by DSC at ∼60 °C is side chain melting. New vibrational bands of the C_β-H out-of-plane bending were identified and correlated to various structures of P3DDT: the component at 827 cm⁻¹ was assigned to the form II modification; the 806-cm⁻¹ band was ascribed to an intermediate phase with twisted main chains and ordered side chains, and the component at 800 cm⁻¹ was due to doped segments. Based on temperature-dependent spectroscopic analysis, a detailed description of the microstructure and phase transition of P3DDT is presented.