Wojciech Łużny

Structural properties of emeraldine base and the role of water contents: X-ray diffraction and computer modelling study

The series of the polyaniline samples in the emeraldine base form was synthesised in various conditions and then it has been subjected to the experimental X-ray diffraction measurements and computer modelling study. Additionally, the elemental analysis technique was also used. The reasonable models of the crystalline structure of various types of the polymer systems (known as EB-1 and EB-2) are proposed. The presence of the water molecules in the crystalline regions of polyaniline is discussed, and the significant role of these molecules for the structural properties of the emeraldine base samples is explained.

Thermally processable polyaniline protonated with diphenyl phosphate — preparation and structural aspects

Polyaniline free-standing films with enhanced conductivity (65 S/cm) can be prepared by hot pressing of polyaniline protonated with diphenyl phosphate in chlorobenzene. The resulting films show high crystallinity, similar to films of camphor sulfonic acid-polyaniline cast from m-cresol.

Esters of 5-sulfo-i-phthalic acid as new dopants improving the solution processibility of polyaniline: spectroscopic, structural and transport properties of the doped polymer

Abstract Three esters of 5-sulfo- i -phthalic acid, namely di( n -amyl) (ASIP), di(2-butoxyethyl) (BESIP) and di(2-butoxy-2-ethoxyethyl) (BEESIP) 5-sulfo- i -phthalates, were synthesized and tested as polyaniline doping agents with the goal of improving its solution processibility. Polyaniline protonated with these acidic esters is soluble in chloroform, diethyl ketone, hexafluoro-2-propanol, m -cresol and dichloroacetic acid. Solutions of PANI(BESIP) 0.5 in dichloroacetic acid (DCAA) are especially interesting because their spectra are strongly concentration-dependent, showing the change in polymer conformation upon the dilution. The spectra of diluted solutions exhibit features characteristic of the conformation that favors localized charge carriers, whereas with increasing polymer concentration, features ascribed to delocalized charge carriers begin to dominate the spectrum. Diffractograms of PANI(BESIP) 0.5 and PANI(BEESIP) 0.5 films cast from DCAA, in addition to a broad amorphous halo, show a sharp Bragg reflection at low angles (2 θ =2–4°), which is indicative of self-organized supramolecular structures previously observed for other polyelectrolyte like systems with amphiphilic counterions. The highest conductivity (85 S/cm at RT) was obtained for PANI(BESIP) 0.5 .

X-ray study of plasticized polyaniline

Polyaniline (PANI) doped with diisooctyl phosphate (DiOHP) has been investigated by X-ray diffraction measurements. It was found that a lamellar-like structure is stabilized when x, the molar ratio of DiOHP to PANI is equal to 0.2. For x ¼ 0:3 the samples are singularly disordered. For 0:3 < x < 0:5, some molecular ordering is recovered and results in an ill defined layered structure. Finally, for molar ratios greater than 0.5 this ordering is progressively lost. The aged samples show exactly the same sequence as a function of the doping rate but globally with a higher degree of crystallinity for the ordered phases. Results are qualitatively discussed in terms of interplaying of protonation and plasticization effects induced by the doping process. 2002 Elsevier Science Ltd. All rights reserved.

Conductivity of Thin Polymer Films Containing Polyaniline

Thin polymer films containing polyaniline doped with several organic dopants were manufactured and their conductivity was measured. The effect of chloroform vapour on the composite film conductivity was examined. The possibility of fabricating polyaniline-based chemiresistors working as gas detectors was taken into consideration. Resistivity of polymeric films patterned by Solvent Assisted Micromolding was also studied. Furthermore, impedance spectroscopy measurements were performed of thin films of pure doped polyaniline and of its blend with an insulating polymer.

XPS depth profiling of organic photodetectors with the gas cluster ion beam

In this work, the authors study active layers of organic photodetector devices containing phenyl-C61-butyric acid methyl ester and Poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b′)dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C). Thin films are examined by x-ray photoemission spectroscopy coupled with argon gas cluster ion sputtering. The use of massive cluster projectiles instead of monoatomic ions has the advantage of not destroying the chemical structure of organic materials under study. The authors show how simulated aging influences the chemistry of these blends and how these alterations extend from sample surface into the bulk of the film. The authors identify several possible processes resulting from aging, including C=O bond breakage and PBDTTT-C diffusion.

Chemical stability of polymers under argon gas cluster ion beam and x-ray irradiation

In this work, the authors examine chemical stability of polymers under x-ray photoemission spectroscopy (XPS) depth profiling coupled with argon gas cluster ion sputtering. The depth profiles measured for polystyrene, poly(3-dodecylthiophene), and poly(methyl methacrylate) thin films do not reveal changes in the XPS spectra due to cluster bombardment. Nevertheless, x-ray irradiation influences the shape of the sputter craters. The observed features are attributed to cross-linking or chain scission occurring in the polymers.