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An evaluation of ion transport in new biomimetic membranes, which are based on dendronised liquid crystalline polyamines is described. Two-step modification of starting polymer allowed preparation of self-supported membranes. Current-Voltage curves confirmed cation permselective nature of these new membranes and size-dependent preferential selectivity in following order: H + > Na + > Ag + > K + . However, in case of chloride solutions, damage of the membranes was observed and was studied using SEM, TEM and 1 H NMR techniques. Selectivity of self-supported systems was compared with hybrid systems based on similar liquid crystalline polyamines and showed lower selectivity values in case of new membranes. Taking into account improved mechanical stability, extended liquid crystalline behaviour and higher clearing temperature values, these materials seem to address all disadvantages of hybrid systems, therefore are complementary in terms of practical application requiring selective ion transport. [ABSTRACT FROM AUTHOR]

Poly[2-(aziridin-1-yl)ethanol] (PAZE) is a suitable polyamine candidate which can be dendronised with 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy]benzoic acid (TAP) in order to obtain liquid crystalline columnar polyamines, as previously reported. However, the resulting copolymers evidenced a strong tendency to crystallise which leads to the detriment of columnar phase stability and the mechanical properties of the resulting polymeric membranes. In order to overcome this drawback, we successfully prepared LC columnar polyamines based on poly[2-(aziridin-1-yl)ethanol] modified with both TAP and benzoyl chloride at different extents. The presence of the dendron group induces self-assembling into a columnar structure, due to an exo-recognition of the side-chain dendrons, while the benzoyl group is expected to inhibit polymer crystallinity. All copolymers, except one, have lower melting points and exhibit higher clearing temperatures (T c ), when compared to the LC polyamines obtained by modification of PAZE with TAP only, reported in previous studies. In all cases they exhibited LC columnar mesophases after annealing, as inferred by DSC, XRD and POM. When casted as membranes, these columnar copolyamines can be homeotropically oriented under thermal treatment at optimal conditions, as was confirmed by X-ray diffraction studies at low 2θ angles. Additionally, SEM microscopy was used in order to evaluate the morphology of the prepared membranes. [ABSTRACT FROM AUTHOR]

A study of ion transport in a new generation of hybrid biomimetic membranes, which are based on the formation of polymeric ionic wires via exo-recognition and subsequent orientation by thermal treatment, is presented. The specific conductivity of the hybrid membranes, obtained by electrochemical impedance spectroscopy, is not strongly affected by relative humidity and temperature; the values are found around 10 −5 S/cm for all studied materials. However, in the case of ion transport observed by linear sweep voltammetry, the hybrid materials containing homeotropically oriented columns exhibited lower resistance than unoriented samples. The preferential selectivity, expressed as conductance ratio compared to proton cation, show remarkably better results for biomimetic membranes when compared to Nafion ® 117. Low values of methanol crossover are also found. Taking into account these findings, these materials hold great promise for practical application requiring selective ion transport. [ABSTRACT FROM AUTHOR]

A new generation of hybrid biomimetic membranes, combining dendronised liquid-crystalline poly[2-(aziridin-1-yl)ethanol] with different modification degrees and anodized aluminum oxide as support, is reported here. The hybrid membranes are prepared by impregnation of the support with a 30% THF polymeric solution. The presence and homogeneous distribution of the polymeric material inside the membrane is confirmed by Raman spectroscopy and line microanalysis. The polymers show tendency to self-assemble into columns, arraying into columnar liquid-crystalline mesophase. Columns homeotropical-like orientation, as a result of a thermal treatment at optimal conditions, is confirmed by X-ray diffraction studies at low 2θ angles. Polymeric wires, being potential ion conductive pathways, resulting from assembling of polymeric columns are detected by SEM microscopy. Low absorption values for water and aqueous methanol solution are observed for hybrid systems, which suggest limited contribution of water in ion transport. Altogether, the new generation of hybrid membranes represents a promising class of biomimetic materials able to form oriented channels inside inorganic support. [ABSTRACT FROM AUTHOR]

In this study new symmetrical and unsymmetrical imines based on 4-[4-(4-fluorophenyl)1,3-thiazol-2-yl]aniline and 2,2′,5′,2"-terthiophene-5,5"-dicarboxaldehyde or 2,2':5′, 2"-terthiophene-5-carboxaldehyde, respectively, were synthesized by melt condensation with the yield of 86% and 40%. The 5% weight loss of the imines was found in temperature range from 294 to 390 °C in nitrogen, depending on the symmetry of aldehyde used in synthesis. The band gap of symmetrical imine (PV-BLJ-SC13) is lower by about ∼0.33 eV than that of unsymmetrical PV-BLJ-SC14. For both imines the electron density of HOMO level is mainly located on thiophene moieties and is extended to imine bonds in thiazole rings and imine moieties. The theoretical calculations of their HOMO-LUMO levels by DFT methods were also provided. The UV–Vis absorption spectra and cyclic voltammograms of imines both in the form of thin films cast on the electrode as well as dissolved in 1,2-dichloromethane were studied to determine the electrochemical and optical band gap energies as well as correlate the positions of HOMO and LUMO levels obtained by DFT and electrochemical methods. The resistance of imines was approximately 113.8 Ω and 102.4 Ω for PV-BLJ-SC13 and PV-BLJ-SC14, respectively as determined by IR thermal images and have a tendency to decrease by about 17–24 Ω when mixed with PTB7 and PC 71 BM. Both imines showed very bright luminescence. Moreover, optical absorption, photoluminescence and IR thermal images were measured for imine:PTB7 or imine:PTB7:PC 71 BM composite. Finally, simple organic solar cells based on (PTB7:imine):PC 71 BM in weight ratio (4:1):8 and (8:1):13 w/w were constructed and characterized. The highest power conversion efficiency, which was equal to 0.42% was determined for the ITO/PEDOT:PSS/PTB7:PV-BLJ-SC13:PC 71 BM (4:1):8/Al device. In addition, the power conversion efficiency was strongly dependent on the weight ratio of imine in active layer. [ABSTRACT FROM AUTHOR]

Three C 70 fullerene derivatives, namely, C70-BTB and C70-MTB with thiophene or C70-MTP thiophene and pyrrolidyne moieties were synthesized and compared with synthesized C70-IPH containing indene moieties. Moreover, C70-BTB was compared with C60-BTB to analyse in deep the influence of fullerene football and rugby balls on the selected opto-electrical properties of new fullerene derivatives. All fullerene derivatives were characterized theoretically by using both time-dependent and independent density functional theory with the Perdew-Burke-Ernzerhof and Becke-Lee, W. Yang, R.G. Parr. The energy levels of the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) were calculated and compared with corresponding values determined experimentally by cyclic voltammetry (CV). It was found that the LUMO HOMO energy gaps determined by the DFT/B3LYP/6–31G(d) method agree very precisely with the corresponding values obtained in the CV experiments. For the first time a possibility of electropolymeryzation of C60-MTB C70-BTB, C70-MTB and C70-MTP with (E)-1-([2,2′:5′,2′'- terthiophen ]-5-yl)-N-{4-[4-(4- fluorophenyl)-1,3- thiazol -2- yl ]phenyl}methanimine (PV-BLJ-SC14) was shown. All fullerene derivatives and blends with poly(3-hexylthiophene-2,5-diyl) and poly(4,8-bis[(2- ethylhexyl) oxy ]benzo[1,2- b :4,5- b ′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2- ethylhexyl) carbonyl ]thieno[3,4- b ]thiophene-4,6-diyl) were investigated in deep by UV–Vis spectroscopy in the solution and as the solid layers together with photoluminescence spectra. Structural defects of created layers based on new fullerene derivatives were studied by atomic force microscopy and thermal imaging. To summarize, the investigated fullerene derivatives present much better electrical properties than widely used PC 70 BM. Moreover, the indene and pyrrolidine modifications demonstrated the best stability (thermally and at passing current) and electrical performance for all tested modifications. Additionally, a possible molecule rearrangement was observed resulting in improvement of electric conductivity through the layer. Finally, simple bulk-heterojunction polymer solar cells were constructed based on new fullerene derivatives as acceptors. [ABSTRACT FROM AUTHOR]