Ionene copolymer electrolyte obtained from cyclo-addition of di-alkyne and di-azide monomers for solid-state smart glass windows

Abstract A copoly(ionic liquid) (coPIL) based on 1,2,3-triazolium bearing trioxyethylene and tetraoxyethylene spacers was successfully synthesized as electrolyte for all-solid state electrochromic devices (ECD). This polyelectrolyte was produced by reacting triethylene glycol (TEG3)-diazide and tetraethylene glycol (TEG4)-dialkyne monomers through a ‘click’ reaction, copper-catalyzed alkyne-azidecycloadditon (CuAAC), and subsequently underwent several alkylation and anion metathesis. The new coPIL bearing ethylene glycol fragments exhibited excellent thermal degradation temperature (T d10  = 230 °C) and ionic conductivity ( σ  = 8.8 × 10 −5  S cm −1 ) which resulted to an efficient color switching (t c  = 11.8 s and t b  = 6.2 s), a high optical contrast (ΔT = 24%) and a remarkable stability (after 3000 cycles) of a symmetric all-solid-state smart glass window. The structural design of this new polyelectrolyte material and its corresponding properties make it an excellent electrolyte for many electrochemical devices that require zero electrolyte leakage.