Analysis of the Dielectric Properties and Charge Transfer Mechanism in Polyamine-Based Ion-Conducting Membranes

High Resolution Image Download MS PowerPoint Slide A series of copolyamines poly[2-(aziridine-1-yl)ethanol] (PAZE) partially modified with 3,4,5-tris[4-( n -dodecan-1-yloxy)benzyloxy]benzoic acid (TAP) and benzoyl groups have been synthesized and analyzed through broadband dielectric spectroscopy. Both aziridine nonmodified chains and benzoyl groups act as spacers in the backbone and between the lateral chain, respectively. Furthermore, membranes prepared with these polyamines were subjected to a thermal orientation process to enhance their electrical properties for use in energetic applications. Both factors, the presence of the spacer and the orientation, modified the molecular motions. The dielectric spectra revealed at least three different dielectric relaxations (γ, α Tg, α Clear ). The orientation of the membrane shifts the peak of the γ-relaxation to higher temperatures, and the concentration of the TAP dendron appears to have only a minor influence on the movement of this group of molecules. The α Tg -relaxation shows different behavior depending on the dendritic substitution degree and the orientation. The orientation procedure during membrane preparation did not influence the clearing process. However, when the TAP groups are fewer, the clearing process is notably less pronounced. The analysis of the electric conductivity (σ) displayed a significant increase at high temperatures related to the melting and clearing transition zone. The analysis of σ DC showed a decoupling of the charge transfer mechanisms from dielectric relaxations. At low temperatures, the proton conductivity increases due to orientation, and at high temperatures, the spacer provides a more efficient pathway for proton migration. Therefore, a complex relationship between membrane structure and conductive properties can allow fine-tuning of the membranes required for potential applications.