Conduction and electrooptical properties of vanadium-containing polymer electrolyte networks from sol-gel methods with modified poly(ethylene glycol)s and poly(tetramethylene oxide)

Abstract

Poly(ethylene glycol) (PEG) and poly(tetramethylene oxide) (PTMO) were functionalised using ethyl acetoacetate to obtain organic molecules with dicarbonyl groups appended. These polymers were reacted with vanadium isopropoxide to prepare vanadium-based ormocers, using a sol-gel method. Low frequency electrical conductivities of the lithiated hybrid coatings were studied by impedance spectroscopy. Both polyethers performed as good polymer electrolytes using LiN(SO ₂ CF ₃ ) ₂ at [Li ⁺ /O]=0.05. The conductivities were shown to be dependent on the composition of the initial sols as well as on the type of starting polymers. The dependence of alkali ion coordination by polyethers [-(CH ₂ ) _m -O-] (m=2-4) is discussed. A two-step colour change was observed upon applying ±2 V to the solid-state electrochromic window with a response time of <2 min being observed.