I. Kulszewicz-Bajer

Heteropolyanion-doped polypyrrole as catalyst for ethyl alcohol conversion

Abstract Heteropolyanion-doped polypyrrole can serve as a catalyst for ethyl alcohol conversion. The insertion of 12-molybdophosphoric anions into the polymer matrix significantly changes the selectivity of the catalyst with respect to unsupported crystalline H 3 PMo 12 O 40 . For example catalytic conversion of ethyl alcohol carried out on polypyrrole containing 75.5 wt.% of 12-molybdophosphoric anions and standardized by heating in helium, gives acetaldehyde as the main product (51%). On the acid-base centers ethylene (45%) and small amounts of diethyl ether (3.5%) are formed. Standardization of the catalyst by heating in air leads to heavy crosslinking of the polymer with simultaneous restoration of acid molecules. As a result, the selectivity and activity of this catalyst are similar to those of unsupported H 3 PMo 12 O 40 .

Spectroscopic studies of polyaniline protonation with poly(alkylene phosphates)

Abstract Polyaniline doped with poly(alkylene phosphates) has been studied by Fourier transform infra-red, X-ray photoelectron and ultraviolet/visible spectroscopies. The protonation of the polymer was indicated by the appearance of infra-red modes characteristic of polyaniline salts and by the bands typical of polyphosphates at ca. 1000 cm−1. X-ray photoelectron spectra showed a decrease in the concentration of imine groups as well as the co-existence of ionized and unionized phosphates independent of the doping level. The influence of the protonation method on the obtained product was observed.

Poly(3-alkylthiophenes) and poly(4,4′-dialkyl-2,2′-bithiophenes): a comparative study by impedance spectroscopy and cyclic voltammetry

Abstract We have studied the electrochemical behaviour of two families of substituted polymers, poly(3-alkylthiophenes) (PATs) and poly(4,4′-dialkyl-2,2′-bithiophenes) (PDABTs), by impedance spectroscopy and cyclic voltammetry. In the PAT family the redox mechanism separates into two reversible redox reactions intervening at two different potentials. In the case of PDABTs, probably because of better stereoregularity due to the coupling mode between monomers, the redox reaction was found unique. In both cases as for nonsubstituted polymers the total doping charge was decomposed into a faradaic charge resulting from the diffusion of doping ions into small aggregates of compact polymer and a ‘capacitive’ charge due probably to the formation of a double layer around the small aggregates. The diffusion coefficient D was measured and the relation L 2 / D was found to be independent of the polymer thickness L . A relation connecting the capacitive charge to the faradaic charge was derived. In general the ratio between capacitive charge and faradaic charge was found to be lower in polydialkylbithiophenes than in polyalkylthiophenes which present a capacitive effect smaller that nonsubstituted polymers.

Spectroscopic studies of poly(4,4′-dialkyl-2,2′-bithiophenes) — the ‘head-to-head’ analogues of poly(3-alkylthiophenes)

Abstract Poly(4,4′-dialkyl-2,2′-bithiophenes) prepared by chemical polymerizatiok of 4,4′-dialkyl-2,2′-bithiophenes show highly regular structure. Due to different coupling patterns (equivalent to ‘head-to-head’ and ‘tail-to-tail’ coupled rings), their spectroscopic features are different to corresponding, mainly ‘head-to-tail’ coupled poly(3-alkylthiophenes). In particular, their π−π ∗ transition occurs at much shorter wavelengths due to lower conjugation caused by close vicinity of alkyl chains in adjacent thiophene rings. On the basis of the comparative investigation of poly(4,4′-dialkyl-2,2′-bithiophenes) and poly(3-alkylthiophenes) we discuss 13C solid state NMR and FT-IR spectra.

Polythiophenes functionalized with disperse Red 1 chromophore

New polythiophene derivatives containing azo dye side group were prepared via copolymerization of 3-alkylthiophenes and Disperse Red 1 substituted thiophenes.

Polyaniline doped with heteropolyanions: Spectroscopic and catalytic properties

Abstract Acid-base properties of heteropolyacids make it possible to introduce them quite easily into a polyaniline matrix via classical acid-base doping. The present work shows that a new type of polymer-supported catalyst can be obtained in this way. It has been discovered that such catalysts are active in ethyl alcohol conversion. Of the two methods of synthesis studied, i.e. preparation of polyaniline and its protonation in two separate steps and the one-step procedure, the former results in more catalytically active products. This is presumably caused by the hindered diffusion of heteropolyanions between polymer chains in the former case. Thus, they stay mainly at the surface of the polymer matrix and are more easily accessible for the alcohol.

Poly(3-n-Butylthiophene) tetrachloroferrate: Preparation, spectroscopic and morphological studies

Abstract Oxidative polymerization of 3-n-butylthiophene with FeCl3 leads to a good-quality soluble poly(3-n-butyylthiophene), whose morphology depends on the casting conditions. Dense or porous films with uniformly distributed pores can easily be obtained. Cast films can be doped to give highly-conducting poly(3-n-butylthiophene) tetrachloroferrate with Mossbauer parameters (I.S. = 0.34 mm/s, Q.S. = 0.28 mm/s) and e.p.r. parameters (g = 2.033, ΔHpp = 570 G) very similar to the corresponding parameters of polyacetylene tetrachloroferrate, but markedly different from those of polypyrrole tetrachloroferrate.

Vibrational dynamics in dendridic oligoarylamines by Raman spectroscopy and incoherent inelastic neutron scattering.

Vibrational dynamics in triarylamine dendrimers was studied in a complementary way by Raman and infrared (IR) spectroscopies and incoherent inelastic neutron scattering (IINS). Three molecules were investigated, namely, unsubstituted triarylamine dendrimer of the first generation and two dendrimers of the first and second generation, substituted in the crown with butyl groups. To facilitate the assignment of the observed IR and Raman modes as well as the IINS peaks, vibrational models, based on the general valence force field method (GVFF), were calculated for all three compounds studied. A perfect consistency between the calculated and experimental results was found. Moreover, an important complementarity of the vibrational spectroscopies and IINS was established for the investigated dendrimers. The IINS peaks originating mainly from the C-H motions were not restricted by particular selection rules and only dependent on the IINS cross section. To the contrary, Raman and IR bands were imposed by the selection rules and the local geometry of the dendrimers yielding mainly C-C and C-N deformation modes with those of C-H nature of much lower intensity. Raman spectroscopy was also applied to the studies of the oxidation of dendrimers to their cationic forms. A strong Raman resonance effect was observed, since the spectra of the studied compounds, registered at different levels of their oxidation, strongly depended on the position of the excitation line with respect to their electronic spectrum. In particular, the blue (458 nm) excitation line turned out to be insensitive toward the cationic forms yielding very limited spectral information. To the contrary, the use of the red (647 nm) and infrared (1064 nm) excitation lines allowed for an unambiguous monitoring of the spectral changes in dendrimers oxidized to nominally monocationic and tricationic states. The analysis of oxidation-induced spectral changes in the tricationic state indicated that the charge storage configuration predominantly involved one spinless dication of the quinoid bond sequence and one radical cation. However, small numbers of dications were also found in a nominally monocationic state, where only radical cations should have been present. This finding was indicative of some inhomogeneity of the oxidation.

Heteropolyanions doped polyimine—Preparation and spectroscopic properties

It is demonstrated that aromatic polyimine obtained by the condensation of p-phenylenediamine and terephtalaldehyde can be chemically doped with heteropolyanions of Keggin-type. The spectroscopic studies show that polyimine undergoes protonation. The structural identity of the Keggin units are preserved upon incorporation into the polymer matrix.

Tuning of Ferromagnetic Spin Interactions in Polymeric Aromatic Amines via Modification of Their π-Conjugated System

Polyarylamine containing meta-para-para-aniline units in the main chain and meta-para-aniline units in the pendant chains was synthesized. The polymer can be oxidized to radical cations in chemical or electrochemical ways. The presence of meta-phenylenes in the polymer chemical structure allows for the ferromagnetic coupling of electronic spins, which leads to the formation of high spin states. Detailed pulsed-EPR study indicates that the S = 2 spin state was reached for the best oxidation level. Quantitative magnetization measurements reveal that the doped polymer contains mainly S = 2 spin states and a fraction of S = 3/2 spin states. The efficiency of the oxidation was determined to be 74%. To the best of our knowledge, this polymer is the first example of a linear doped polyarylamine combining such high spin states with high doping efficiency.