POLYIMIDE POLYETHER MIXED CONDUCTORS AS SWITCHABLE MATERIALS FOR ELECTROCHROMIC DEVICES

A new family of redox-active polymers have been obtained by polyconden sation of alpha,omega-diamino oligopolyethers with various aromatic te tracarboxylic acid anhydrides. The polyether blocks retain the usual c ation co-ordination ability leading to solid-state ionic conduction wh ile the relatively large electron affinity of the bis-imide moieties f ormed in the block polymers allows the reversible formation of stable radical anions (circle(-) and circle circle(2-)) in the range 2-2.6 V vs. Li degrees. Either slow-scan or microelectrode voltammetry indicat e that the totality of the redox centres in such materials are readily accessible for all polyether spacer lengths tested (6-22 ether fragme nts), suggesting both a fast electron-exchange mechanism between anion radicals and a tendency for self assembly (stacking) of the planar ar omatic groups. When increasing the number of atoms in the aromatic rin g, the peak separation became smaller (benzene > naphthalene > perylen e), resulting ultimately in simultaneous 2-electrons injection. These materials, due to the high coloration efficiency of the reduced state and their ready processability in thin films are excellent candidate f or the realisation of laminated solid-state electrochromic devices.