Structural investigations on bulk poly(3-hexyl thiophene): combined SAXS, WAXS, and AFM studies

A detailed structural and morphological study on bulk poly(3-hexylthiophene), having high regioregularity (about 98%) and molecular weight of 16 kDa, has been performed. The combination of wide- and small-angle X-ray diffraction techniques, for the first time on bulk semicrystalline conjugated polymer, allowed to get insight on the structural features of poly(3-hexylthiophene), subjected to different thermal treatments. The evolution or the periodicity, the crystallite dimension and defects, as a function of the annealing were determined. Fibrillar organization, evidenced atomic force microscopy, results in the coexistence of disordered areas where fibrils are randomly oriented and ordered regions where fibrils are organized into stacks, with periodic pattern matching the periodicity determined by X-ray scattering.