Janusz Płocharski

Modifications of crystalline structure of peo polymer electrolytes with ceramic additives

Abstract Modifications of PEONaI polymer solid electrolytes by adding alumina powders were studied. Conductivity of prepared flexible films was improved at least one order of magnitude in comparison to pristine PEONaI electrolytes. The results were compared with those obtained previously by us for PEO based composite solid electrolytes containing NASICON.

Mixed solid electrolytes based on poly(ethylene oxide)

Polymer solid electrolytes from a PEO-NaI system were mixed with Nasicon and Al2O3 powders. As a result an increase of ionic conductivity exceeding 10−1 S/cm at room temperature was observed for both cases. This increase was due to a higher concentration of amorphous phase which resulted apparently from a higher nucleation rate during the solidification process. The samples were studied using impedance spectroscopy, X-ray diffraction, electron microscopy, NMR, and other techniques.

Study of electrorheological properties of poly(p-phenylene) dispersions

Samples of powdered poly(p-phenylene) lightly doped with ferric chloride were dispersed in silicone oil and the observed electrorheological (ER) effect was studied. The conjugated polymers were obtained in three different synthetic procedures resulting in materials of different crystallinity, which was then additionally modified by annealing in vacuum. The polymer samples were carefully characterized and their electric conductivity and permittivity, doping level, x-ray diffractograms, Fourier-transform infrared spectra, and grain size distribution were determined. The influence of these properties on the magnitude of the ER phenomenon was examined. It was found that the ER activity of the suspensions depended strongly on the crystallinity of a dispersed polymer. This observation was correlated with the ionic conductivity of the material leading to the conclusion that the ER effect in suspensions of FeCl3 doped polyphenylene resulted from bulk polarization processes relying on movement of ions within the p...

Performance of acrylate-poly(ethylene oxide) polymer electrolytes in lithium batteries

Results for the performance of lithium/Mn02 batteries containing solid polymer electrolytes based on poly(ethylene oxide) blends with some acrylic derivatives are presented. The ionic conductivities of the electrolytes are promising for battery application. It was found, however, that interfacial phenomena impair the battery efficiency. Impedance spectroscopy shows resistive limitations at the anode interface of the batteries, caused either by formation of an electrically distinguishable resistive layer or by chemical interaction between the polymer and lithium, influencing, most probably, the kinetics of the lithium oxidation reaction.

Electrorheological properties of polyphenylene suspensions

Abstract Electrorheological (ER) fluids are currently being extensively investigated since their technical applications look very promising. The effect relies on rapid and reversible changes of viscosity of an ER fluid upon application of electric field. Doping of a conjugated polymer increases its electrical conductivity σ and dielectric constant e. Since factors determining values of these two parameters are different, it is sometimes possible to prepare a material of high e and low σ, which is the basic requirement for a main component of an ER fluid. Thus, conjugated polymers can be used in formulation of these fluids. Poly( p -phenylene) (PPP) treated with ferrous chloride was chosen and its bulk electrical properties were investigated by means of impedance spectroscopy. The values of e were 40–130 and the values of σ were 10 −8 -10 −6 S/cm. ER fluids were prepared from the polymer powder and silicone oil, and their ER properties were studied. The fluids exhibited Bingham-like behaviour. The magnitude of the ER effect increases with e but saturation at dielectric constants exceeding 100 is observed. This saturation seems to be a general feature of any ER fluid. Correlations between material parameters of the doped bulk PPP and the ER effect are shown.

New transparent, colorless, metallically conductive polymer films and their electrochemical transformations

New surface conductive polymer composite films exhibiting extraordinary properties: high conductivity with metallic temperature dependence and exceptionally high transparency are presented. The conducting networks in these materials are formed of plate-like nanocrystals of bis(ethylenedioxy)tetrathiafulvalene (BEDO-TTF) salts with iodine or bromine. The films with bromine salts are colorless and transparent while those with iodine are colored. It is demonstrated that colored films with (BEDO-TTF)/iodine networks can be electrochemically transformed into highly transparent, practically colorless materials without deterioration of the conducting network. The resulting metallically conducting polymer materials show the highest transparency among conductive composites reported so far.

Mixed conductivity in poly(p-phenylene) doped with iron chloride

Abstract Poly( p -phenylene) is a conjugated polymer that becomes conductive after doping. It has been demonstrated that the amorphous polymer lightly doped with iron(III) chloride exhibits both electronic and ionic conductivity in the range 10 −8 –10 −5 S/cm. Annealing the pristine amorphous polymer and doping it to the same level leads to a partially crystalline material, the exclusively electronic conductivity of which is one order of magnitude higher. The relative dielectric constant, however, seems to be unaffected by the polymer structure. The temperature dependencies of both components of the conductivity were measured giving similar values of activation energies within the range 0.29–0.36 eV.

Impedance spectroscopy and phase structure of PEONaI complexes

Abstract PEONaI solid electrolyte foils were prepared and their impedance spectra registered. The influence of salt concentration, molecular weight of the polymer and temperature were related to the parameters of the equivalent circuit. The phase structure of the studied samples wa − investigated by a pulse NMR method.

Anisotropy of thermoelectric power of stretch-oriented new polyacetylene

Abstract Samples of stretch-oriented new polyacetylene were synthesized and doped with iodine or ferric chloride. Thermoelectric power was measured between 4 and 300 K. Linear (‘metallic’) relations were observed with significant anisotropy of the thermopower. The direction of higher thermopower was the same as the direction of higher conductivity. This phenomenon was explained assuming intrinsic inhomogeneity of the polymer.

Electrorheological effect in suspensions of conductive polymers

Abstract Electrorheological (ER) effect relies on increase of viscosity of a fluid under electric field. In the present study electrorheological fluids (ERFs) were prepared out of FeCl 3 doped poly( p -phenylene) and silicone oil. Rheological properties of the ERFs were measured under electric field up to 2.2 kV/mm. Influence of electric field and composition of the fluids on magnitude of the ER effect were studied. It was found that the ER effect is observed in ERFs containing amorphous polymer and not a semi-crystalline one. This has been attributed to ionic contribution of conductivity in the amorphous polymer which is not present in the crystalline material.