Charge Transport and Dipolar Relaxations in Hyperbranched Polyamide Amines

Broadband dielectric spectroscopy, pulsed field gradient nuclear magnetic resonance (PFG NMR), and differential scanning calorimetry are combined to study charge transport and dipolar relaxations in novel hyperbranched polyamide amines. The dielectric spectra are dominated by conductivity contributions at higher temperatures (masking out the structural α-relaxation process), whereas two secondary dipolar relaxation processes are observed at lower temperatures for the two samples investigated. Based on Einstein and Einstein−Smoluchowski relations, the diffusion coefficient is extracted from the dielectric spectrain quantitative agreement with independent PFG NMR measurements. It exhibits a Vogel−Fulcher−Tammann temperature dependence, while the effective number density of the charge carriers varies only weakly with temperature. Charge transport and structural α-relaxation are found to be characterized by a decoupling index of ∼7 for the hyperbranched polymers studied.