Relaxation phenomena and conductivity mechanisms in anion-exchange membranes derived from polyketone

Effect of Relaxations on the Conductivity of La1/2+1/2x Li1/2-1/2x Ti1-x Al x O3 Fast Ion Conductors

Perovskite-type solid-state electrolytes, Li_3x La_2/3-x TiO₃ (LLTO), are considered among the most promising candidates for the development of all-solid-state batteries based on lithium metal. Their high bulk ionic conductivity can be modulated by substituting part of the atoms hosted in the A- or B-site of the LLTO structure. In this work, we investigate the crystal structure and the long-range charge migration processes characterizing a family of perovskites with the general formula La_1/2+1/2x Li_1/2-1/2x Ti_1-x Al _x O₃ (0 ≤ x ≤ 0.6), in which the charge balance and the nominal A-site vacancies (n _A = 0) are preserved. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) investigations reveal the presence of a very complex nanostructure constituted by a mixture of two different ordered nanoregions of tetragonal P4/mmm and rhombohedral R3̅c symmetries. Broadband electrical spectroscopy studies confirm the presence of different crystalline domains and demonstrate that the structural fluctuations of the BO₆ octahedra require to be intra- and intercell coupled, to enable the long-range diffusion of the lithium cation, in a similar way to the segmental mode that takes place in polymer-ion conductors. These hypotheses are corroborated by density functional theory (DFT) calculations and molecular dynamic simulations.

Bathochromic-Shifted Emissions by Postfunctionalization of Nonconjugated Polyketones

Most nontraditional intrinsic luminescent (NTIL) polymers currently show blue fluorescence. Tuning the emission color of NTIL polymers is of fundamental importance for their applications, but it still remains a scientific challenge. Herein, we initially develop an efficient strategy for bathochromic shifting of NTIL polymers by through-space acceptor-donor charge transfer between the in chain and the side chain. A variety of functionalized polyketones (FPK-R; where R = H, Ph, Me, tBu, F, and Cl) with furan rings built into the polymer chain were prepared by the Paal-Knorr reaction. FPK-R polymers showed bright and bathochromic-shifted fluorescence compared with their counterparts. The emission color could be tuned by changing the postfunctionalization conversion and varying the styrenic monomer substituent. Experimental and theoretical investigations revealed that the color tunability originated from enhanced through-space charge transfer between the side chain phenyl and the in chain furan rings.