Unusual Electret Properties in a Soft Pyridine-based Polymer Material

Recently it was shown, that coupling free and bounded protonated polymer pyridine molecule can form a dipole with a dipole moment about 7-12 D.¹ֲ ֲ Addition of co-polymer in composition, containing ester groupsֲ lead to appearance of volume charge complexes, in which with high probability O-NH donor-acceptor group form ionic complexes ²ֲ ֲ meaning presence in a material quasy- permanently dipoles. A Cryo-TEM image of polymer aggregates is presented on Fig.(a). ֲ ֲ Poling by application of DC bias highly polarizable species leads to orientation polarization.ֲ Super sensitivity over all range from white light till far IR (14 mcm is a limit of a range of equipment capability), complete reversibility of photoinduced changes are characterized such aggregates. ֲ ֲ Study of material structural changes with FTIR, was not successful, meaning only high rate processes involved in electrical induced polarization.ֲ To study short time processes, molecular probe ג€“ Rhodamin 6G (R6G) had been incorporated and fluorescence lifetime of R6G had been measured during switch off/on DC bias: emission lifetimeֲ ֿ„= 4,523 ns without DC field and this value splits for two under applied bias: ֿ„₁ֲ = 4.9 ns ; ֿ„₂= 3.6 ns (Fig.(b)).ֲ Quantum mechanical modeling allows us to relate the electric field induced changes in the electro-optical behavior to changes in the ground state geometry and electronic structure of the complex.

Figure (a). Cryo-TEM image of preformed aggregates; (b)R6G fluorescenceֲ (emission at 561nmֲ excitation at 420ֲnm) with (red line) and without (green line) application of DC bias.

References: (1) Vaganova, E., et al., J. Phys. Chem.B, 2010, 114, 10728-10733; (2) Vaganova, E., et al., ֲ J. Phys. Chem. C 2012, 116, 25028-25033.