Softening behavior and conductivity in ionene polymer glasses

Ionene glasses are considered as being a new class of materials. Their properties have been investigated in detail by thermoanalytical, solid state NMR, and dielectric techniques. The segmental dynamics of these cationic polyelectrolytes, labeled in chosen positions, have been studied with solid state 2H‐NMR. Below the glass transition the quaternized ammonium groups in the polymer backbone are essentially static, due to strong Coulomb interactions. The glass transition in these materials is characterized by the softening of a network formed by the N+‐cations. However, both the low molecular weight counterions and the organic chain segments linking the ammonium groups are already mobile below Tg. The dynamics of the organic segments in the glassy state can be described as motion between fixed ends. Ionic conductivity in the glassy state is based on thermally activated anion transport. The influence of the flexibility of the organic chain segments and of the type of the anion on the conductivity are discussed. A simple analytic expression is proposed to describe the conductivity behavior in the low frequency limit.