Nanocomposites and nanomaterials

Dielectric behavior of solid polymer electrolyte films formed by PEO-containing double hydrophilic block copolymers
Kunitskaya L., Zheltonozhskaya T., Nesin S., Minenko N., Klepko V.
Institute of Macromolecular Chemistry of the NAS of Ukraine. 48 Kharkivs’ke shosse  St, Kyiv-02160, Ukraine.
E-mail: larisa_kunitskaya@ukr.net

A solid polymer electrolytes (SPEs) with high ionic conductivity at room temperature has been an importance subject due to their interest in the all solid-state electrochemical devices development. Nowadays, the mainstream polymer matrix of the SPEs remains poly(ethylene oxide)  (PEO) and its derivatives. However, the high crystallinity of PEO leads to low ion conductivity and inferior Li+ transference numbers (0.2–0.3) at room temperature, which affects the high rate capability of LBs. 
In the present work, we investigated diblock- (DBC) and triblock (TBC) copolymers comprising chemically complementary poly(ethylene oxide)/polyacrylamide which form intramolecular polycomplexes (IntraPCs) and due to this allow to reduce PEO crystallization. We also examined DSCs and TBCs partially hydrolyzed derivatives as possible ion-conducting membranes. 
Measurement of dielectric characteristics of the studied systems was performed in the frequency range 102-105 Hz using a dielectric spectroscope developed on the basis of the AC bridge P5083 and a three-electrode cell.  
It is noticed that ionic conductivity of TBC membranes depends on PEO-block length. Thus, the increase in Mn of PEO-blocks from 6∙104 to 3.5∙104 kDa led to an increase in ionic conductivity of TBC membranes from 6,2·10-11 to 3,2·10-9 Scm-1 respectively. The introduction of additional ionic groups -COOH in polyethylene oxide/poly(acrylamide-co-acrylic) acid chains has a positive effect on the conductive characteristics of copolymer membranes for both DBCs and TBCs samples. The ionic conductivity of the investigated membranes filled with LiPF6 increased with increasing salt content. The obtained results made it possible to consider PEO/PAAm block copolymers with interacting blocks as perspective matrices for producing solid electrolyte membranes and their possible application in Li-ion batteries, dye-sensitized solar cells and fuel cells.