Conformational Changes of Doped Polyaniline as Characterized by Small-Angle Neutron Scattering (SANS)

Abstract : The use of small-angle neutron scattering (SANS) and solution viscosity were used to study the conformation changes of doped and undoped polyaniline (PANI) in l,l,l,3,3,3-hexafluoro-2-methyl-2-propanol (HFIP). In this study, solutions of deuterated polyaniline DOPED WITH DEUTERATED METHANE SULFONIC ACID (MS A) were prepared in non-deuterated (FIFIP) solvent, which dissolved both forms of PANI and thus facilitated comparison between the insulating and conducting states of PANI. The use of two different standard models Zimm and Debye (Gaussian) coil was needed to treat the SANS data in order to analyze the weight average molecular weight, Mw, radius of gyration, Rg, and the second virial coefficient, A2. The conformation of polyaniline was strongly influenced by the degree of doping as evidenced by the both the increase in intrinsic viscosity and the radius of gyration. Doped PANI adopted an expanded conformation and allowed for an increase in the second virial coefficient.