Synthesis and properties of PEDOT derivatives containing liquid crystalline groups

We have developed novel liquid crystalline conjugated polymers consisting of alternating blocks of EDOT and phenylene units substituted with two mesogenic groups. The chemical polymerization was carried out in dimethylformamide with a Ni(cod) catalyst. Electrochemical polymerizations were also examined in acetonitrile and tetrahydrofuran. The monomer was electropolymerized onto platinum button and ITO glass electrodes by repeated scanning from −1.6 V to + 1.6 V versus Ag/Ag+ at 20 mV/s. The polymer was electrochromic and reversibly switching from deep purple to emerald green upon oxidation. The polymer structure was confirmed by NMR, IR, GPC, and elemental analysis. Optical absorption and photoluminescence measurements were performed. Thermal and liquid crystalline properties of the polymers were investigated by optical polarizing microscopy and differential scanning calorimetry (DSC). The combination of liquid crystalline (LC) and electrochromic properties allowed us to obtain color tunable liquid crystal materials with optical anisotropy. The polymer may find use as a new functional material for “liquid crystalline electrochromic device”.