Composites of PUR and IL were prepared and specific conductivities and Shore A hardness were determined. IL were based on 1‐alkyl‐3‐methylimidazolium salts with counterions BF, PF, triflate, or ethylsulfate. Presence of IL increased the conductivity by five orders of magnitude. Variation of alkyl chain length and nature of counterions only had little effect on the conductivity. Presence of IL had a plasticizing effect, which was most pronounced for the IL with dodecyl groups and PF as counterion. In broadband dielectric measurements, the complex conductivity showed a characteristic dispersion that is caused by the interplay between (hopping) transport of charge carriers and electrode polarization.magnified image

Polyiminoarylenes with carbazole (cbz) units in the main chain, or main and side chain and thermally cleavable t-butyloxycarbonyl (boc) groups were prepared upon palladium-catalyzed coupling reactions. Polymers were prepared from 2,7-dibromo-9-(2-ethylhexyl)-carbazole M1 and 9-(4-aminophenyl)carbazole hydrochloride M3 (P1-EH), 2,7-dibromo-9-t-butyloxycarbonyl-carbazole M2 and M3 (P1-BOC), M1 and 4-t-butylaniline M4 (P2-EH), or M2 and M3 (P2-BOC). Thermal treatment of boc-substituted polymers P1-BOC and P2-BOC at 180°C for ≥4 h led to removal of the boc groups and formation of insoluble polymers P1-H and P2-H with strong adhesion to the substrate due to hydrogen bonding ('latent hydrogen bonding'). For P1-BOC the rate constant k of deprotection could be determined to be about 0.050 min −1 . Size exclusion chromatography indicated that the molecular weights of the polymers were between 14 100 and 28 100 g mol −1 . Polymers P1-EH, P1-BOC, P2-EH and P2-BOC were readily soluble in toluene, THF, dichloromethane, chloroform, and benzene, and insoluble in acetone and methanol.After removal of the boc groups the resulting polymer films of P1-H and P2-H were insoluble in common organic solvents. Optical and electrochemical properties of the polymers were investigated. Due to the electron-rich nitrogen atoms in the main chain, the polymers can be easily oxidized. Oxidation starts at about 0.31 V vs. SCE with formation of cation radicals. Further oxidation occurs at 0.55 V with formation of dications, and at 0.71 V with oxidation of main chain cbz units. At about 1 V the side chain cbz units are oxidized. The polymers are electrochromic and exhibit color changes from colorless via orange to green and blue. Cbz oxidation at potentials ≥0.71 V leads to the formation of dimers in a side reaction. Thermal cleavage of the boc groups leads to well-adhering films of P1-H and P2-H due to hydrogen bonding of the carbazole N-H-groups between polymer chains, and polymer and ITO-substrate. The best performance with regard to reversible oxidation and adhesion was found for P1-H. For this polymer a reversible electrochromism was found. A contrast ratio of 12% at 900 nm, and a switching time of 400 ms were determined.

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