A study of conducting polymer morphology: the effect of dopant anions upon order

The authors discuss a series of freestanding conducting polypyrrole and poly-3-methylthiophene films prepared and examined by x-ray diffraction and transmission electron microscopy (TEM). The degree of order observed polypyrroles was highly dependent upon the incorporated dopant'' anions and also on deposition conditions. Examination of a large variety of dopant systems showed that substituted benzenesulfonate and long aliphatic chain monoanions imparted the highest order, and chemically prepared polypyrroles were less ordered than their electrochemical counterparts. Doped poly-3-methylthiophene exhibited comparable order, yet was less flexible in its ability to incorporate large dopant anions. Crystalline phases were detected by electron diffraction in some polymer systems.