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All solid-state poly(ethylene oxide) (PEO) nanocomposite electrolytes were made containing nanoscale fillers of layered double hydroxides (LDHs). Two kinds of LDHs with different surface states were prepared by aqueous co-precipitation method. The LDHs were added into PEO matrix to study the structures, conductivities and ionic transport properties of nanocomposite electrolytes. The structures of LDHs were characterized by infrared spectra, thermogravimetric analysis and wide-angle X-ray diffraction. With enhanced compatibility of LDH sheets by oligo(ethylene oxide) surface modification, the PEO/OMLDH nanocomposite electrolyte exhibits an amorphous morphology and an enhancement of conductivity by three orders of magnitude as compared to pure PEO electrolyte. The lithium ion transference number T Li + of PEO/LDH nanocomposite electrolyte measured with a value of 0.42 is two times higher than the one of pure PEO electrolyte, which can be attributed to the Lewis acid–base interaction between surface states of metal hydroxides and counter anions of lithium salts.

For neutral poly(3-alkylthiophene)s (P3ATs), the electric modulus formalism of dielectric relaxation measurement together with the use of nonexponential decay function can be applied to describe the behavior of conductivity relaxation and carrier transport. The charge mobilities of neutral P3ATs calculated from conductivity relaxation with the use of the defect-diffusion model are in agreement with the data from field-effect transistor measurement. The temperature dependence of charge mobility exhibits a local maximum right after the end of glass transition region, which can be attributed to the transition of soft conformons in the disordered phase to localized conformons. The charge mobilities and activation energies of mobilities for P3ATs are dependent on conjugation length and volume fraction of conducting units. © 1994 John Wiley & Sons, Inc.

Measurements on polyaniline using dielectric analysis (DEA, −50°C to 240°C, 0,4 Hz to 105 Hz), differential scanning calorimetry (DSC, 30°C to 240°C) and infrared spectroscopy (IR) after heat treatment from 25°C to 300°C are carried out. After conversion of DEA results to complex electric modulus, the conductivity relaxation time distribution can be obtained, which remains unchanged for temperatures below 160°C and becomes narrower in the temperature range from 180°C to 240°C due to the occurrence of crosslinking reactions, as is confirmed by the exothermic behavior above 160°C and by the decrease of the relative intensity of quinoid absorption with respect to that of the aromatic ring. The crosslinking reaction causes a decrease in dc conductivity, a narrowing in conductivity relaxation time distribution and an increase in activation energies for conductivity and conductivity relaxation.

Conductivity relaxation of neutral poly(3-hexylthiophene) is analyzed based on temperature and frequency dependence of its electric conductivity and electric modulus. The frequency dependence of the electric modulus is well fitted by the nonexponential decay function, exp[−(t/τp)β], with fractional exponent β (0

For neutral poly(3-hexylthiophene) (P3HT), the electric modulus formalism of dielectric relaxation measurement together with the use of non-exponential decay function can be applied to describe the behavior of conductivity relaxation. The charge mobility of neutral P3HT calculated from conductivity relaxation frequency with the use of the defect-diffusion model is in agreement with the data from field-effect transistor measurement. The temperature dependence of charge mobility exhibits a local maximum right after the end of glass transition region, which can be attributed to the transition of soft conformons in the disordered phase to localized conformons.

The conductivity relaxation behavior of neutral poly(3-alkylthiophene)s (P3ATs) with the alkyl side chain having carbon numbers 4, 6, 8, and 12 is investigated on the basis of dielectric rexation measurements at -100 to 180 o C and 0.4-10 5 Hz after conversion to complex electric modulus formalism. It is found that the conductivity relaxation time distribution can be represented by the nonexponential decay function, φ(t)= exp(-t/τ p ) β involving a relaxation time distribution parameter β and a characteristic relaxation time τ p as in the case of vitreous ionic inorganic conducting materials

The conductivity relaxation of poly(3-alkylthiophene)s (P3ATs) is analyzed by use of electric modulus analysis together with non-exponential decay function to investigate intrinsic conduction mechanism of neutral P3ATs. A correlation with the thermal transitions from dynamic mechanical analysis and UV-Vis spectroscopy is attempted. It is found that conductivity relaxation behavior is highly related to the molecular motion. The side chain motion has no significant effect on the charge transport. While in the glass transition and rubbery region, relaxation time distribution becomes broadened with temperature. As the coplanar subchains in the ordered region melt, the conjugation length decreases and its distribution (and therefore relaxation time distribution) becomes narrower. The intrinsic conduction mechanism of neutral P3AT is determined by thermal activated hopping of charge carriers over energy barrier resulting from conformational defects such as soft or localized conformons.

Photoresponsive conductivities of copolymers of 3-hexylthiophene and azobenzene-modified 3-hexylthiophene prepared by chemical oxidation with FeCl3 were measured by placing a thin film (40 μm thick) in between an ITO glass and a disk-like Cu electrode. Upon irradiation of UV-light (γ=365 nm) (100 W Hg-lamp), conductivities of the copolymersincrease by a factor of 0.1 to 1.5 depending on the amount of the azobenzene moiety within 5 min to maxima and, upon turning off the light, return to original levels within the same period of time. Reversibility of the photoresponsive conductivity is excellent. It is found that the increase in conductivity upon irradiation is not due to a variation in interchain distance resulting from trans-cis isomerization in the azobenzene-moiety. This phenomenon can be attributed mainly to a generation of photoexcited hopping sites in the azobenzene moiety.

Dielectric relaxation (−90°C to 120°C, 0,4 Hz to 105 Hz) and ultraviolet-visible (UV/Vis) spectroscopic (−100°C to 200°C) measurements for poly(3-octylthiophene) were carried out. A correlation of complex electric moduli, which were converted from dielectric measurements, with thermal transitions from UV/Vis and dynamic mechanical analysis indicates (i) no significant effect of side-chain motion on charge transport; (ii) in the glass transition and rubbery regions relaxation time distribution becomes broadened with temperature; (iii) as the coplanar subchains in the order region melt, the relaxation time distribution becomes more narrow.