Structural Study of Doped and Undoped Polythiophene in Solution by Small-Angle Neutron Scattering

Abstract

Small-angle neutron-scattering studies have been carried out on solutions of the conjugated polymer poly-3-butylthiophene. At room temperature positive interchain interactions occur even at concentration as low as 0.1 g/1. At $T=65\ifmmode^\circ\else\textdegree\fi{}$C the statistical length $b=55$ \AA{} of isolated neutral chains has been measured. Upon doping of the polymer chains, a large conformational transition occurs. In the dilute regime, the charged polymer chains are in a rodlike state. Doped-conjugated-polymer solutions do not behave like common polyelectrolytes.