Broadband Dielectric Spectroscopy and Its Application in Polymeric Materials

Relaxation processes in polymeric systems span over an extremely wide range of time scales. There are a few experimental techniques capable of covering such a range, and one of the most versatile of them is Broadband Dielectric Spectroscopy (BDS). Current BDS covers an enormous frequency range, from ~10^-5 to ~10¹² Hz, enabling a practical study of the full spectrum of relaxation phenomena in a broad temperature and pressure range without involvement of time-temperature superposition. In this article, we present capabilities of the BDS technique on examples of different polymeric systems and explain what kind of information can be extracted from the frequency spectra of the dielectric permittivity and conductivity. We present examples of dielectric studies of segmental and chain dynamics, secondary relaxations, explain additional phenomena in multicomponent systems (e.g. polymer nanocomposites and block copolymers), and discuss specifically examples of ion-conducting polymers. We emphasize that BDS does not probe molecular motions directly and measures fluctuations of dipoles or diffusion of charges. So, combination of BDS with other experimental techniques is the best approach to study dynamics of various materials.