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The hexagonal perovskite derivatives Ba3NbMoO8.5, Ba3NbWO8.5, and Ba3VWO8.5 have recently been reported to exhibit significant oxide ion conductivity. Here, we report the synthesis and crystal structure of the hexagonal perovskite derivative Ba3-xVMoO8.5-x. Rietveld refinement from neutron and X-ray diffraction data show that the cation vacancies are ordered on the M2 site, leading to a structure consisting of palmierite-like layers of M1Ox polyhedra separated by vacant octahedral layers. In contrast to other members of the Ba3M'M″O8.5 family, Ba3-xVMoO8.5-x is not stoichiometric and both barium and oxygen vacancies are present. Although synthesized in air at elevated temperatures, Ba3-xVMoO8.5-x is unstable at lower temperatures, as illustrated by the formation of BaCO3 and BaMoO4 by heat treatment in air at 400 °C. This precludes measurement of the electrical properties. However, bond-valence site energy (BVSE) calculations strongly suggest that oxide ion conductivity is present in Ba3-xVMoO8.5-x.

Ionic liquids (ILs) are salts consisting of organic cations and inorganic/organic anions having melting transitions lower than 100°C. They hold promise as engineered materials in a variety of modern fields. They are used as green solvents or catalysts for chemical reactions, biocatalysts, biopolymers processing, active pharmaceutical ingradients in medicine, even as electrolytes for batteries. For batteries applications, ionic liquids must have high ionic conductivity, but most of the ionic liquids (monocationic) have low conductivities. To address this limitation, we describe in this chapter dicationic ionic liquids based on extended viologens. The colossal conductivities, σdc ~ 10−1.5·S cm1 of new diatonic ionic liquids in the same range of benchmark materials/electrolytes applied in fuel cells and batteries is reported. The relatively new class of ionic liquids consist of extended viologen bistriflimides containing oligoethyleneoxy groups were prepared via Zincke reaction under mild conditions and are excellent candidates as components in devices for energy conversion and storage applications. The synthesis and ionic conductivities of other ionic liquids and dicationic organic salts will be contrasted with dicationic ionic liquids in this chapter.

Glycolipids prepared from palm kernel oil, PKO, in tropical regions represent an excellent opportunity to develop new surfactant formulations for cosmeceutical and pharmaceutical applications while...

We have assessed the potential of light-responsive bent-core liquid crystals as candidate materials for energy conversion and storage applications. Samples comprise two chromophore bent-core compounds containing either one (IP33) or two (IP31) azobenzene groups, and their 5% (molar) mixtures with one non-chromophore bent-core compound (NG75), which was also measured as a reference material. The pristine compounds and their mixtures were introduced in thin transparent Indium Tin Oxide (ITO) cells, and were characterised by polarised optical microscopy, UV-visible spectrophotometry, impedance spectroscopy, and ferroelectric analysis, under different conditions of electrical fields and UV irradiation. All materials display smectic C polar phases (SmCP) except IP31, which forms columnar phases (Col), and IP33, IP31 and their mixtures exhibit light-responsiveness when irradiated at 365 nm due to reversible trans-to-cis photoisomerisation of the azobenzene units. All the bent-core based materials exhibit, at least, two dielectric relaxations, associated with different modes of molecular reorientation under weak alternating electrical fields (1 Vrms), as well as ferroelectric response that leads to permanent polarisation under the application of strong alternating fields (∼75 kV cm−1) at frequencies associated with the Goldstone-mode (1 Hz). Samples show considerable conductivity values and relaxor behaviour for liquid crystals, which can be tuned by application of UV light. In addition, we have induced in IP31 isothermal phase transitions from columnar to smectic phases (via the isotropic melt), by a combination of light and electrical stimuli. Our results confirm the potential of these bent-core compounds as light-harvesters for energy applications., IDC would like to thank the Universitat Politècnica de València (UPV), for the FPI grant (PAID-2019-SP20190013), the Generalitat Valenciana (GVA) and the European Social Fund (ESF), for the FPI grant (ACIF/2020/233) and the mobility grant (CIBEFP/2021/53). NFKA would like to thank Universiti Teknologi MARA (UiTM) for sponsoring her academic sabbatical leave and allowing her to work on this project. AMF would like to thank the Carnegie Trust for the Universities of Scotland, for the Research Incentive Grant RIG008586, the Royal Society and Specac Ltd., for the Research Grant RGS\R1\201397, the Royal Society of Chemistry for the award of a mobility grant (M19- 0000), and the Scottish Government and the Royal Society of Edinburgh for the award of a SAPHIRE project. The authors from INMA greatly appreciate financial support from projects of the Spanish Government PGC2018-093761-B-C31 [MCIU/AEI/FEDER, UE] and the Gobierno de Aragón/FEDER (research group E47_20R). Thanks are given to the nuclear magnetic resonance, mass spectrometry, and thermal analysis services of the INMA (Univ. Zaragoza-CSIC).

The authors would like to acknowledge Mathew Abdy and Daniel Zaton for their help preparing the samples, Prof. Corrie Imrie and Prof. John Storey for their continuous advice, and the School of Engineering (University of Aberdeen) for financial support.

The hexagonal perovskite derivatives Ba

International audience; Two series of new dicationic stilbazolium salts containing tosylate and triflimide counterions, respectively, were synthesized and characterized by spectroscopic techniques and elemental analysis. Despite of their promesogenic structures, none of these salts are mesomorphous, and instead they solely exhibit crystalline polymorphism, as deduced from differential scanning calorimetry, polarizing optical microscopy and variable temperature X-ray measurements. These salts were also found to be highly thermally stable with decomposition temperatures occurring well above 300 °C, and up to 367 °C for the triflimide salts, as determined by thermogravimetric analysis. UV–Vis absorption and photoluminescent properties were examined in both solution and in the solid state. They exhibited higher absolute quantum yields in the powdered state than in solution. The dielectric response was evaluated by impedance spectroscopy, revealing notable values of short-range conductivity in triflimide salts through amorphous regions. Our work demonstrates the potential of these new stilbazolium salts as advanced materials in optoelectronic devices, with performances that can be tailored by molecular design of the spacer’s flexibility and choice of counter anions.

In the search to obtain new and more efficient components of memory devices, we report the photochromic, dielectric and electrochemical response of a light-responsive organic compound, and its memory performance under electrical fields. The so-called N(1)-[12-(4-(4′-isobutyloxyphenyldiazo)phenoxy)dodecyloxy)]thymine, tAZOi, molecule contains one azobenzene group, which provides with photochromic character, and one terminal thymine group, capable to form hydrogen bonds and assemble supramolecular dimers, (tAZOi)2. We have calculated the optical absorption coefficient, extinction coefficient and refractive index of tAZOi, which obeys the single oscillator Wemple–DiDomenico model. An ITO/tAZOi/Al device has been prepared and presents two switchable conductance states with preservation of memory performance. The mechanism linked to the resistive random-access memory (RRAM) has been evaluated by molecular modelling and is controlled by p-type conduction, possibly involving hydrogen-bonding. Upon UV irradiation at ∼ 365 nm, tAZOi displays an increase in the complex permittivity driven by trans-to-cis (E-to-Z) isomerisation of the azobenzene groups. Molecular simulations suggest that conductivity and device performance can be enhanced (and controlled) by light exposure through the formation of activated Z isomers that could transfer charge to other neighbouring molecules, resulting in photo-electric responsive devices., TSV acknowledges financial support from the Ministry of Higher Education of Malaysia through the Fundamental Research Grant Scheme [FP079-2018A]. AR acknowledges Ministerio de Economía y Competitividad (MINECO) for his PhD grant BES-2015-071235, under the project MAT2014-55205-P. VMA acknowledges the University Malaya for the grant RF004B-2018. AMF would like to thank the Royal Academy of Engineering, U.K., for the grant NRCP1516/4/61 (Newton Research Collaboration Programme), the University of Aberdeen, for the award of the grant SF10192, the Carnegie Trust for the Universities of Scotland, for the Research Incentive Grant RIG008586, the Royal Society and Specac Ltd., for the Research Grant RGSR1201397, and the Royal Society of Chemistry for the award of a mobility grant (M19-0000). AMF and TSV further acknowledge University Malaya for travelling support.

In the search for novel smart multifunctional liquid crystalline materials, we report the synthesis, thermal and structural characterisation, and the conductivity, of a set of new block and statistical copolymers, containing light-responsive mesogenic groups (MeOAzB), polar sulfonic acids (AMPS), and methyl(methacrylate) groups (MMA). By using a cascade of reversible addition-fragmentation chain polymerisations, RAFT, we have tailored different side-chain polymeric structures by controlling monomer composition (MeOAzB/AMPS/MMA) and configuration. We have yielded simultaneous liquid crystalline behaviour and appreciable conductivity in polymers with low concentrations of polar acid groups, by the formation of smectic phases in narrow aggregates. The light-responsiveness of the polymers, via reversible trans-to-cis photoisomerization of azobenzene groups, and the local activation of conductivity at relatively low temperatures, opens the possibility to prepare polymer electrolytes for energy conversion and storage, whose conductivity could be controlled and optimised by external stimuli, including light irradiation.

The phenomenon of vector photochromism was observed in some high-efficient polarization-sensitive materials depending on the radiant exposure of the inducing linearly polarized actinic light. When radiant exposure exceed certain value specific to each material, a sharp change in the transmission spectrum of the probing linearly polarized nonactinic beam is observed after analyzer. While probing with unpolarized light the transmission spectrum is practically unchanged and does not depend on the magnitude of the radiant exposure. The mechanism of this phenomenon is discussed. The effect is an interference nature and depends on the path difference between the ordinary and extraordinary rays in material with photo-induced anisotropy. It is shown that the kinetics of this effect depends on the photosensitive layer thickness and the concentration of the chromophore.The beams with a wavelength away from the absorption band of the material were used as a probing. It is shown that in this case birefringence has made the main contribution in photoanisotropy. The experiments were carried out for polarization-sensitive materials with varying degrees of components integration, in particular, two synthesized side-chain azopolymers obtained by immobilization of polar azo dyes on polymethylmethacrylate backbone. It is shown that the maximum value of the birefringence Δn = 0.162 achieved in azopolymers with covalently bonded components. In this case a third order of interference of the probing beam is observed., The authors gratefully acknowledge support by the Shota Rustaveli National Science Foundation [grants number 04/06 and AR/209/6-120/14] and Science& Technology Center in Ukraine [grant number 6069].

We apply UV light to control the stability of twist-bend nematic phases, NTB, and conventional nematic phases, N, in three new liquid crystalline nonsymmetric dimers containing cyanobiphenyl and light-responsive azobenzene fragments connected by a hexyloxy spacer. The dynamic and static (5 kHz) dielectric responses of (E)-4′-(6-(4-((4-(ethoxy)phenyl)diazenyl)phenoxy)hexyl)-[1,1′-biphenyl]-4-carbonitrile, CB6OAzO2, (E)-4′-(6-(4-((4-(hexyloxy)phenyl)diazenyl)phenoxy)hexyl)-[1,1′-biphenyl]-4-carbonitrile, CB6OAzO6, and (E)-4′-(6-(4-((4-hexylphenyl)diazenyl)phenoxy)hexyl)-[1,1′-biphenyl]-4-carbonitrile, CB6OAz6, are measured at different temperatures, in planar and homeotropic alignments, by the application of bias and alternating electrical fields. The three CB6OAz(O)n dimers show high values of the dielectric mean, e ¯ , and dielectric anisotropy, Δ e , due to the dipole moment associated with the cyanobiphenyl groups. The absence of the ether linkage to the terminal chain in CB6OAz6 reduces the NTB - N transition temperature and increases the bend elastic constant, K3, compared to those seen for CB6OAzO6. Isothermal phase transitions are promoted by light-irradiation, via trans-to-cis photoisomerisation of the azobenzene units, resulting in the disruption of the liquid crystal order and appearance of re-entrant nematic and isotropic phases at low temperatures. It is possible to control the dynamics and reversibility of these transitions by varying the chemical structure of the new dimers, the temperature and UV light dosage. This may be exploited in devices using multiple external stimuli.

It is known that polarization holography uses photoanisotropic materials to record the state of light polarization. The polarization-holographic method of storage, transformation, transmission and processing of information is one of the most promising directions not only in optical but also in general among information technologies. The potential of increasing sensitivity of certain types of materials to light polarization is not yet fully mastered. In this paper, azodyecontaining photoanisotropic polymers are represented as a result of the study of polarization-sensitive materials, which are distinguished from their predecessors by outstanding photosensitivity. The report shows results of improving the foreground photoanisotropic characteristics, such as: increasing the degree of light-inducible birefringence and the rate of acceleration of this process. Which is the main measuring criterion of photosensitivity and effectiveness of the studied materials. The efficiency of azodye based polarization-sensitive materials is based on integration of their components by forces of electrostatic interactions or covalent bonds. In our previous works we have repeatedly shown clearly all the advantages of the results achieved by the molecular electrostatic integration of the material components. The presented paper shows different advantages of photoanisotropic materials consisting of alternative, covalent bonds, from which the increased velocity of photoanisotrophy and significantly improved magnitude of photosensitivity are worth noting on the first hand. Based on the experiences accumulated as a result of the conducted recent research and the developed recommendations, the new polarization-sensitive materials have deliberately been synthesized and studied.

This work was funded through the LIFE LIBERNITRATE project (LIFE16 ENV/ES/000419) in the framework of the LIFE+ funding programme. EA and AMF acknowledge the traineeship Erasmus+ grant for Laura Ong.

A series of asymmetric viologen bistriflimide salts of both short and long alkyl chains were synthesized by the metathesis reaction of lithium triflimide salt with the respective asymmetric viologen dibromide salts in methanol. Their thermotropic liquid crystalline properties were determined by differential scanning calorimetry, polarizing optical microscopy and variable temperature X-ray diffraction techniques. These salts melt into highly-ordered smectic T phases that is, crystal-to SmT transitions (Tms) at relatively low temperatures (lowest Tm at −12 °C) and maintain liquid crystallinity in a wide range of temperatures (8–132 °C), with excellent thermal stabilities up to 320 °C as determined by thermogravimetric analysis. These results differ with respect to the symmetric viologen bistriflimide salts. Ionic conductivity of these salts was also measured by dielectric impedance spectroscopy and found to be in the 10−2.5 S cm−1 range, highlighting their potential as electrolytes at room temperature.

We have prepared and characterised a series of side-chain liquid crystalline homopolymers and terpolymers containing different azobenzene derivatives (RAzB), sulfonic groups (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS), and methyl(methacrylate) groups (MMA), as monomeric units. We have evaluated the effect of different para-substitutes of 6-(4-azobenzene -4′-oxy)hexyl methacrylate, at the side chains, OCH3, NO2 and H, on the phase behaviour and conductivity of the new polymers. The copolymers can form smectic and nematic phases, depending on their composition, and have light responsiveness, conferred by the azobenzene chromophores. The terpolymer with methoxy terminations, MeOAzB/AMPS/MMA, exhibits the highest conductivity values of the series (10−2/10−3 S·cm−1 range) through liquid crystalline phases and with signs of decoupling from polymeric segmental motions. These materials are promising candidates to develop new light-responsive polymeric electrolytes for electrochemical conversion devices in which ionic conductivity under anhydrous conditions can be controlled by their nanostructure.

Hydrogen bonding is an efficient alternative to covalent bonding as a way to stabilise liquid crystallinity, by yielding symmetric and non-symmetric complexes with increased molecular anisotropy. In designing new hydrogen-bonded liquid crystals, HBLCs, it is crucial to account for the competing hydrogen bonds that can lead to different supramolecular species coexisting in a temperature-dependent equilibrium. Thus, as part of a systematic development of this area, in the present work we study with detail the relationships between the phase behaviour and hydrogen bonding in a series of 4-n-alkoxybenzoic acids, nOBAs, which are widely used as components in HBLCs. Five acids with alkyl chain lengths of n = 1, 4, 5, 7 and 8 have been investigated using Fourier transform infrared spectroscopy, FTIR, in a broad range of temperatures under two different experimental configurations: sandwiched between potassium bromide, KBr, windows and dispersed in KBr discs. The nematic phase is correlated with the amounts of closed dimers between acid molecules, through the formation of strong hydrogen bonds. Moreover, high concentrations of open dimers are found in samples sandwiched between KBr slides, which are linked to the appearance of smectic-like aggregates that perturb the local order of the nematic phase. The results are interpreted in terms of the ability of the 4-alkoxybenzoic acids to align due to surface interactions, which are less acute in samples dispersed in the discs. These effects must be taken into account in order to correctly interpret the information about the supramolecular species present in the samples, and thus to better understand the relationships between hydrogen bond strength and mesomorphism in HBLCs.

The liquid crystal nonsymmetric dimer, 1-(4-butoxyazobenzene-4'-yloxy)-6-(4-cyanobiphenyl-4'-yl) hexane (CB6OABOBu), shows enantiotropic twist-bend nematic, NTB, and nematic, N, phases. The NTB phase has been confirmed using polarized light microscopy, freeze fracture transmission electron microscopy, and X-ray diffraction. The helicoidal pitch in the NTB phase is 18 nm. The NTB-N (TNTBN) and N-I (TNI) transition temperatures are reduced upon UV light irradiation, with the reduction in TNTBN being much larger than that in TNI. An isothermal, reversible NTB-N transition may be driven photochemically. These observations are attributed to a trans-cis photoisomerization of the azobenzene fragment on UV irradiation, with the cis isomers stabilizing the standard nematic phase and the trans isomers stabilizing the NTB phase. The dramatic changes in TNTBN provide evidence that the transition between the normal nematic and twist-bend nematic with spontaneous breaking of chiral symmetry is crucially dependent on the shape of molecular dimers, which changes greatly during the trans-cis isomerization.

We have studied the relationships between liquid crystallinity and hydrogen bonding in mixtures containing 4-pentoxybenzoic acid, 5OBA, and five bipyridines, XBiPy, with spacers having different flexibilities, namely: 4,4′-bipyridine (BiPy), 1,2-bis(4-pyridyl)ethane (EthaBiPy), trans-1,2-bis(4-pyridyl)ethylene (EthylBiPy), 4,4′-trimethylene-dipyridine (PropBiPy), and 4,4′-tetramethylene-dipyridine (ButBiPy). The XBiPy/5OBA mixtures exhibit liquid crystal behaviour for a range of acid concentrations, and predominantly smectic behaviour. The 1 : 2 mixtures have been studied using temperature-dependent Fourier transform infrared spectroscopy, FT-IR, with particular focus on the Fermi bands associated with the hydroxyl groups and on the carbonyl stretching regions. The latter has been interpreted in terms of contributions arising from a number of species, namely the heterocomplex, and free, dimeric and oligomeric acid species. This analysis reveals that the heterocomplexes formed by hydrogen bonding between the unlike species tend to be the dominant species but at all temperatures coexist in equilibria with acid monomers, dimers and oligomers. The hydrogen bond strength in the heterocomplexes is predicted by molecular modelling to be stronger than that in the acid dimers. The smectic behaviour of these mixtures is accounted for in terms of the stabilisation of the layered structures arising from hydrogen bonded catemer strands. The liquid crystal behaviour of these and similar hydrogen bonded liquid crystals, HBLCs, cannot be explained solely by the formation of the heterocomplex between the unlike species, but instead a more realistic view must take into account the presence and concentrations of various different supramolecular species and the interactions between them.

The phase behaviour of equimolar mixtures of 4-octyloxybenzoic acid, OOBA, and either 1-(4-butylazobenzene-4′-oxy)-6-(4-oxypyridine)pentane, BuABO5OPyr, or 1-(4-butylazobenzene-4′-oxy)-6-(4-oxypyridine)hexane, BuABO6OPyr, is reported. OOBA exhibits enantiotropic smectic C and nematic phases, whereas BuABO5OPyr and BuABO6OPyr are not liquid crystalline. Both the OOBA/BuABO5OPyr and OOBA/BuABO6OPyr equimolar mixtures show an enantiotropic smectic A phase identified using X-ray diffraction and polarised light microscopy. The liquid crystallinty of the mixtures is attributed, in part, to the formation of a 1:1 hydrogen-bonded complex between OOBA and either BuABO5OPyr or BuABO6OPyr. Differences in the transitional properties of the mixtures are accounted for in terms of the average shapes of these 1:1 complexes. Temperature dependent FTIR spectroscopy shows, however, that the formation of the complex is not quantitative in the mixtures but instead a complex mixture exists over the complete temperature range studied, involving the 1:1 complex, both cyclic and open acid dimers, free acid and hence, free BuABO n OPyr molecules.

In this work we present a facile and versatile strategy to prepare new amphiphilic compounds obtained from natural sources, avoiding costly covalent synthetic stages, and we introduce a powerful methodology to describe hydrogen-bonding networks in carbohydrates liquid crystals A series of new glycosides has been prepared by mixing a natural-based mannoside, αManPKO, with three different polymeric substrates: poly(ethylene oxide), PEG, poly(4-vinyl pyridine), P4VP, and a block-copolymer containing PEG and P4VP segments, PEG45-b-P4VP18. The materials have been characterised by differential scanning calorimetry, polarised optical microscopy and small-angle X-ray diffraction. The resulting complexes are assembled by hydrogen-bonding and form smectic A phases, with the polymeric chains spread along the surface of the glycosides bilayers. By using Fourier-transform infrared spectroscopy, FT-IR, and molecular simulations, we have assessed the selectivity of the hydrogen bonds formed between αManPKO and the polymeric segments. Our results suggest that the assembly of the polymeric complexes must be explained by a combination of interfacial mixing between the polymer/glycoside units at the bilayer boundaries (favoured by PEG) and the formation of strong hydrogen bonds (favoured by P4VP)., This work was supported by the Ministry of Education of Malaysia [FRGS/1/2019/TK05/UITM/02/9, 2019]; Royal Academy of Engineering, U.K., and Academy of Science, Malaysia [NRCP1516/4/61, 2016]; University of Aberdeen [SF10192, 2018] and University Malaya [UMRG grant RP038B-17AFR].

A spouted bed was simulated through two Computational Fluid Dynamic models: CFD-TFM and CFD-DEM. The two models were compared and validated with data from literature, showing good agreement between experimental and simulated results. Both models were able to predict the dynamics of the bed from the static situation to stable spouting conditions, even though some discrepancies in the solid volume fraction or velocity profiles were observed. Overall, CFD-DEM reproduced better the experimental measurements, and, since the computational effort was proved to be similar in both cases due to the low number of particles in the bed, it was preferred to describe the present spouted bed. In larger systems, however, CFD-DEM might not be so convenient, requiring the evaluation of the degree of accuracy and the computational costs prior to the application of this or alternative models.

The spontaneous formation of a chiral phase via molecular recognition in a system consisting of achiral components is reported. Specifically, the liquid crystalline behaviour of two molecular complexes assembled by hydrogen bonding between a stilbazole-based template and alkoxybenzoic acids has been characterised. The complexes exhibit the heliconical twist-bend nematic phase (NTB) over a broad temperature range despite the hydrogen-bond acceptor not being liquid crystalline and the donor exhibiting the conventional achiral nematic phase.

This article belongs to the Special Issue Intramolecular Hydrogen Bonding 2018., We assess the assembly of supramolecular complexes by hydrogen bonding between azocompounds and a diacylaminopyridine monomer by temperature-dependent Fourier transform infrared spectroscopy (FT-IR) and density functional theory (DFT) calculations. The electronic delocalisation in the supramolecular rings formed by multiple hydrogen bonds stabilises the complexes, which coexist with dimeric species in temperature-dependent equilibria. We show how the application of readily available molecular modelling and spectroscopic techniques can predict the stability of new supramolecular entities coexisting in equilibria, ultimately assessing the success of molecular recognition., A.M.F. and D.Z. would like to acknowledge the School of Engineering (University of Aberdeen) for funding. M.P., L.O. and A.M.-F. would like to acknowledge the Spanish Ministry of Science for the MAT2017-84838-P project.

The paper presents the study of the polarization-sensitive materials developed by us. It is demonstrated the advantages of these light-recording organic media composed both via covalent bindings and through electrostatic interactions.

[EN] We have prepared a series of new ionically conducting polymer electrolytes consisting of side-chain liquid crystal terpolymers with mesogenic azobenzenes, sulfonic acid groups and methyl methacrylate. The poly[10-(4-methoxyazobenzene -4'-oxy)decyl methacrylate] -co-poly[2-acrylamido-2-methyl-1-propanesulfonic acid]-copoly [methyl methacrylate]s, 10-MeOAzB/AMPS/MMA terpolymers, were synthesised by a one-pot conventional radical polymerisation. All samples were characterised by NMR, GPC/SEC, FT-IR, POM, XRD, DSC, UV-visible spectrophotometry and EIS. The terpolymers have light responsive properties, and exhibit liquid crystallinity over a wide range of compositions. Above a certain threshold of AMPS content, the 10-MeOAzB/AMPS/MMA terpolymers exhibit ionic conductivities in the 10(-8)-10(-4)S.cm(-1) range, with signs of decoupling of ionic mobility from segmental motions of the polymer., ARG and AMF thank the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs, and the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03 and UPOVCE-3E-013 and the awarding of two FPI and FPU pre-doctoral grants. AMF and NFKA would like to thank the Royal Academy of Engineering for the award of the Newton Research Collaboration Programme grant NRCP1516/4/61. AMF acknowledges the School of Engineering of the University of Aberdeen for financial support.

The phase behaviour of equimolar mixtures of 6-(4'-cyanobiphenyl-4-yl)hexyloxybenzoic acid (CB6OBA) with either 1-(4-butylazobenzene-4'-oxy)-5-(4-oxypyridine)pentane (BuABO5OPyr) or 1-(4-butylazobenzene-4'-oxy)-6-(4-oxypyridine)hexane (BuABO6OPyr) is reported. CB6OBA shows a monotropic twist-bend nematic phase and an enantiotropic nematic phase whereas the two pyridyl-based components do not exhibit liquid crystallinity. Both equimolar mixtures (CB6OBA/BuABOnOPyr) show enantiotropic nematic phases. The nematic-isotropic transition temperature and associated entropy change are higher for the CB6OBA/BuABO6OPyr mixture than for the CB6OBA/BuABO5OPyr mixture. This may be accounted for in terms of the average shapes of the hydrogen-bonded 1:1 complexes formed between the two differing components in the mixtures. However, Fourier transform infrared spectroscopy reveals that this complex is not formed quantitatively, but instead a complex mixture exists over the complete temperature range studied, involving the 1:1 complex, both cyclic and open acid dimers, free acid and hence, free BuABOnOPyr molecules.

Event: SPIE OPTO, 2017, San Francisco, California, United States: Organic Photonic Materials and Devices XIX., The well-known scalar photochromism phenomenon is a reversible phototransformation of chemical species between two forms having different absorption spectra. It is observed under the action of actinic light regardless of its polarization state. Unlike this in some high-efficient polarization-sensitive azopolymeric materials, we have observed a welldeveloped vector polyphotochromism which appears as a light-induced area with spectral selectivity for the linearly polarized probing beams. A sharp change in the transmission spectrum of the material have been observed when we placed an irradiated area of the sample between crossed polarizers, while the transmission spectrum of the sample remained practically unchanged in case of probing by unpolarized light. The effect has a purely vector nature, while the transmission spectrum of the exposed material essentially changes in case of observing between crossed polarizers and the change in the spectrum unambiguously depends on the energy exposure. A significant dependence of the kinetic of the vector polyphotochromism induction on the power density of linearly polarized actinic light (445 nm) is shown for probing beam of 635 nm. It is also shown that the kinetics of the effect depends on the photosensitive layer thickness and the concentration of the chromophore. The experiments were carried out for two synthesized side-chain azopolymers obtained as immobilized polar azo dyes on polymethylmethacrylate backbone. It is clearly shown a light-controlled spectral selectivity of the sample activated by the various doses of the stimulating radiation., The authors gratefully acknowledge support by the Shota Rustaveli National Science Foundation and Science & Technology Center in Ukraine (STCU) under grants No. AR/209/6-120/14 and No. 6069 (04/06).

The phase behaviour and mesomorphism of poly(4-(6-propenoyloxyhexyloxy)benzoic acid) (PPOHBA) and 4-pentyloxybenzoic acid (POBA) is studied using variable-temperature Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction. PPHOBA exhibits a smectic C phase and POBA, a nematic phase. The temperature dependence of the Fermi resonance bands associated with the hydroxyl groups and of the carbonyl stretching region in the FTIR spectra indicates that there is a dynamic equilibrium between monomers and open and closed dimers formed by hydrogen bonding between benzoic acid moieties. The nematic phase observed for POBA is linked to the anisotropic cyclic dimer, while an abrupt increase in the concentration of monomer drives isotropisation. In PPOHBA, hydrogen-bonded supramesogens promote smectic behaviour, while hydrogen-bonded crosslinks stabilise the lamellae. The increased viscosity arising from this dynamic crosslinking is offset by the flexibility of the acrylate backbone and alkyl spacers.

The liquid crystalline behaviour of methyl-6-O-(n-dodecanoyl)-α-D-glucopyranoside, 1, has been characterised using X-ray diffraction and variable temperature Fourier transform infrared (FTIR spectroscopy). 1 exhibits a monotropic interdigitated smectic A phase consisting of bilayers in which the alkyl chains are overlapped. The crystal–isotropic transition is accompanied by a pronounced decrease in the strength of the hydrogen bonding network involving the sugar groups resulting in a marked change in the environment of the alkyl chains. The isotropic phase consists of disordered smectic-like domains stabilised via hydrogen bonding between the sugar groups. At the transition to the smectic A phase, a subtle change in hydrogen bonding is observed which is manifested by a change in the temperature dependence of the OH stretching peak position in the FTIR spectrum. On crystallisation, the strong hydrogen bonding network is re-established accompanied by a change in the conformational distribution of the alkyl ...

[EN] A multi-rate non-isothermal kinetic analysis of the isotropic-melt to liquid crystalline phase transition of novel liquid crystalline ionogenic copolymers, LCIs, the 10-(4-methoxyazobenzene-4'-oxy)decyl methacrylate]-co-2-(acrylamido-2-methyl-1-propanesulfonic acid)s, 10-MeOAzB/AMPS, copolymers, has been performed by means of calorimetric experiments. An analytical methodology which includes the study of the phase transition rate parameter, the determination of the activation energies by using Kissinger and Flynn-Wall-Ozawa models, and the study of the phase transition kinetics by the use of the Avrami theory, has been applied. The formation of the mesophases from the isotropic state occurred close to thermodynamic equilibrium. The results evidence the presence of several individual processes in the formation of liquid crystalline phases from the melt and a strong dependence of phase transition rates and activation energies with acid contents. A decrease in the phase transition rate, related to a decrease in the overall change of the transition entropy, has been observed. The final inhibition of the liquid crystal (LC) behaviour is ascribed to an exponential increase in the activation energy of the phase transition, promoted by strong acid aggregation. An optimum composition of the 10-MeOAzB/AMPS copolymers to achieve the dual characteristics of LCIs (ionogenic and liquid crystalline behaviour) requires acid concentrations capable of promoting structure-forming effects on the LC phases and the evolution of phase separated morphologies., The authors would like to acknowledge the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03, UPOVCE-3E-013, ENE2011-28735-C02-01, IT-2009-0074 and three FPI and FPU predoctoral grants, and the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs and the ACOMP/2011/189 program. The Vice-rectorate for Research of UPV is also thanked for additional support through the PAID 05-09-4331, PAID-05-11/2806, and PAID 06-11-2037 projects.

[EN] The dielectric response of a series of side-chain liquid crystal copolymers, SCLCPs, the poly[6-(4'-methoxyazobenzene-4'-oxy)hexyl methacrylate]-co-poly[methyl methacrylate]s, MeOAzB/MMA copolymers, is presented in the frequency range f = 10(-2) to 107 Hz and over the temperature interval T = 150 to 120 degrees C. The relaxation spectra of these polymers have been studied in terms of the complex dielectric permittivity (epsilon' and epsilon '') and the dielectric loss tangent, tan(delta). The electric modulus, M*, has been also calculated. It is possible to distinguish two relaxations zones, one at low temperatures (including gamma and beta relaxations) and another at higher temperatures (including the alpha and beta 1 relaxations), all of them reported for liquid crystalline poly(methacrylate)s. The individual relaxations have been analyzed using Havriliak-Negami (HN) functions, and the effect of conductivity at high temperatures is subtracted. The thermal activation of the relaxations at low temperatures is studied using the Arrhenius equations as a function of copolymer composition, while the alpha and beta 1 relaxations are analyzed using Vogel-Tammann-Fulcher equations. The activation entropy has been also evaluated for all the relaxations through the Eyring equation. The temperature ranges, activation energies, and entropies of the relaxations at low temperatures (gamma and beta) are similar in the homopolymer and copolymers. However, the introduction of MMA units promotes variations in all the parameters related to the relaxations associated with the motions of the ester groups adjoining the polymer backbone. Specifically, a decrease is observed in the activation entropy values of the beta 1 relaxation, which suggests that the activation of the local motions of the side groups involves smaller cooperative regions in the copolymers with respect to the homopolymer. This fact may account for the extinction of the smectic behavior, together with the dilution of the anisotropic interactions between the mesogenic units on increasing MMA content. The study of this beta 1 relaxation can be then applied to anticipate the formation and stability of smectic phases in functionalized SCLCPs, by controlling the local mobility resulting in different mesogenic behavior., This paper is meant to be a tribute and recognition to the research activity of Professor Giulio Sarti. The authors would like to thank Dr. Victor Saenz de Juano for his advice during the discussion of the results and also the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03, UPOVCE-3E-013, IT2009-0074, and ENE2011-28735-C02-01 and two FPI and FPU predoctoral grants, and the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs and the ACOMP/2011/189 program. UPV is also thanked for additional support through the PAID 05-09-4331 and PAID-06-11 programs.

Phenomenon of vector polyphotochromism was observed in some high-efficient polarization-sensitive materials dependent on the radiant exposure when material was illuminated with linearly polarized actinic light. The phenomenon has purely vector nature.

The synthesis and characterisation of a novel non-symmetric liquid crystal dimer, 1-[3-O-(d-glucopyranos-3-yl)]-8-[(4-methoxyazobenzene-4¿-oxy)] octane is reported. This exhibits glassy behaviour and a highly interdigitated smectic A phase in which the aromatic and alkyl structural fragments overlap. Variable temperature infrared spectroscopy reveals that the strength and extent of hydrogen bonding within the system does not show a marked change at either the glass transition or at the smectic A-isotropic transition. This observation indicates that the smectic A-isotropic transition is driven by changes in the van der Waals interactions between the molecules while hydrogen bonded aggregates persist into the isotropic phase. © 2012 Elsevier Ltd. All rights reserved., J.M.S. is pleased to acknowledge support from the EPSRC Platform Grant EP/G00465X and A. M. F from the Grisolia Program from Generalitat Valenciana.

[EN] A series of novel side chain liquid crystal copolymers, the poly[10-(4-methoxy-4'-oxy-azobenzene) decyl methacrylate]-co-poly[2-acrylamido-2-methyl-1-propanesulfonic acid]s (10-MeOAzB/AMPS-x/y) have been synthesised by free radical copolymerisation. The mol fraction of the sulfonic acid-based group, AMPS, has been varied over a broad range of composition in the copolymers, and these have been characterised using differential scanning calorimetry (DSC), polarised light microscopy (PLM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). The liquid crystal homopolymer and copolymers containing up to 0.54 mol fraction AMPS-based units, all exhibit a smectic A phase, while at higher mol fraction AMPS-based groups, liquid crystallinity is extinguished and the copolymers are amorphous. The local packing arrangements within the smectic A phase varies with composition attributed, in part, to phase separation between acid rich domains and liquid crystal regions. The dependence of the transitional properties on copolymer composition may be interpreted in terms of the packing efficiency of the mesogenic side chains and hydrogen bonding between the sulfonic acid groups, as a consequence of increasing the concentration of acid-based groups. (c) 2012 Elsevier Ltd. All rights reserved., The authors thank the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs, and the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03, UPOVCE-3E-013, ENE 2011-28735- CO2-01 and IT-2009-0074 and the awarding of two FPI and FPU predoctoral grants.

The spectroscopic and thermal properties of swollen Nafion membranes in methanol aqueous mixtures were investigated to understand the behavior of commercial electrolytes in the presence of polar solvents. Several differences were observed in the absorption processes depending on the composition of the solvent. Deconvolution methods were applied to study specific contributions of solvents and polymer groups based on Fourier transform infrared spectroscopy and thermogravimetric analysis. The results evidence compositional effects on the interactions between solvents and Nafion. A major influence of the nonpolar domains (hydrophobic regions) in the absorption of methanol together with a reduction of the interactions with sulfonate groups was observed. Such changes are accompanied by a modification of the cluster morphology of the equilibrated membranes evaluated by differential scanning calorimetry. These findings can be useful to improve the knowledge on Nafion’s microstructure in the presence of polar solvents, The authors thank the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs, and the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03, UPOV08-3E-013, IT2009-0074, ENE2011-28735-C02-01 and the awarding of two FPI and FPU predoctoral grants.

[EN] Transport phenomena through polymeric composite membranes depend on several complex factors, involving not only their chemical composition but also their microstructure. Due to the combination of mesomorphic and macromolecular behaviour, thermotropic liquid crystal polymers (LCP) may enhance the transport properties in membranes by improving parameters related to the order, orientation, connectivity and distribution of the different domains arising from phase separation. This paper provides an overview of some existing and potential applications of liquid crystals (LC) in polymeric membranes as effective structure-directing templates or as components providing a dynamic response to external stimuli. The first part is a description of the composition and phase behaviour of LCP containing ionic and ionogenic groups, the so-called liquid crystal ionomers (LCI). The second part is focused on the description of LCP and LCI used in transport applications, such as proton-conducting films in fuel cells, ionic polymer transducers and hydrogels. The paper highlights the relationships between the composition and the LC properties of the materials and their potential as membranes for ionic and solvent transport, with particular attention paid to covalently linked materials prepared by copolymerisation, due to their higher versatility and stability., The author would like to especially thank Professor Amparo Ribes-Greus, from Universitat Politecnica de Valencia, UPV, and Professor Corrie T. Imrie, from the University of Aberdeen, UoA, for their support during the discussion of this work, and also the researchers and students from the research group of Degradation and Recycling of Polymeric Materials in the Institute of Materials Technology (ITM) of UPV. Also acknowledged for their financial support are the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03 and UPOVCE-3E-013, the Ministry of Education and Science for the awarding of two FPU and FPI pre-doctoral grants, and the financial support of the Generalitat Valenciana, through the Grisolia and the ACOMP/2011/189 program. The UPV is also thanked for additional support through the PAID 05-09-4331 programme.

The effect of the degree of hydrolysis of poly(vinyl alcohol) (PVA) substrates on the preparation and properties of crosslinked membranes prepared via esterification with sulfosuccinic acid (SSA) has been studied using attenuated total reflectance-Fourier transform spectroscopy (ATR-FTIR) and thermogravimetric analysis (TGA). Three PVA substrates with degrees of hydrolysis of 89, 96, and 99% were crosslinked using SSA at high temperatures. FTIR spectroscopy revealed that esterification occurred in all the membranes and to some extent, prior to heat treatment. The final morphology of the membranes was dependent on both the SSA concentration and the composition of the PVA substrate. Thermogravimetric analysis showed an increase in the thermal stability of the PVA-SSA membranes with respect to their PVA substrates arising from the formation of a crosslinked structure. In addition, TGA revealed the presence of free and tightly bound water in the PVA-SSA membranes. Thermal treatment had a more pronounced effect on the properties of the PVA substrates having higher degrees of hydrolysis. The results from the swelling tests, the ionic exchange capacities (IEC) and the tests in DMFC monocells demonstrated that a balance between water and methanol selectivity and ionic conduction determines the potential of these materials to act as electrolytes in fuel cells, Contract grant sponsor: Generalitat Valenciana; contract grant number: Grisolia and Forteza 2010 and 2011.

Two different series of polymer dispersed liquid crystal (PDLC) films were prepared for their future use as externally controlled electrolytes in direct methanol fuel cells (DMFC). The liquid crystals used in this work were commercial cholesteryl oleyl carbonate (COC) and n-(4-methoxybencylidine)-4-butylanilyne (MBBA); cellulose acetate (CA) was used as the polymer substrate. All the films were characterized by differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) to analyze the existence of interactions between the components, the modification of the liquid crystal behavior and the thermal stability of the films. The two series of films exhibited very different behaviors. While the films containing CA and COC maintained most of the properties characteristic of the pure components, including the COC mesomorphism, the analysis of films containing CA and MBBA revealed the existence of strong interactions between the components that promoted the inhibition of the MBBA mesomorphic behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The liquid crystalline phase behavior of 4-[6-(4'-cyanobiphenyl-4-yl)hexyloxy]benzoic acid (CB6OBA) and 4-[5-(4'-cyanobiphenyl-4-yloxy)pentyloxy]benzoic acid (CBO5OBA) is described. Both acids show an enantiotropic nematic phase attributed to the formation of supramolecular complexes by hydrogen bonding between the benzoic acid units. In addition, CB6OBA provides the first example of hydrogen bonding driving the formation of the twist-bend nematic phase. The observation of the twist-bend nematic phase for CB6OBA, but not CBO5OBA, is attributed to the more bent molecular shape of the complexes formed by the former, reinforcing the view that shape is a key factor in stabilizing this new phase. Temperature-dependent FTIR spectroscopy reveals differences in hydrogen bonding between the two nematic phases shown by CB6OBA which suggest that the open hydrogen-bonded complexes may play an important role in stabilizing the helical arrangement found in the twist-bend nematic phase.

[EN] Radiation cross-linked ultra high molecular weight polyethylenes (UHMWPEs) have been successfully used as wear resistant bearing surfaces in total joint arthroplasty. A recent development in this field is the incorporation of the antioxidant vitamin E into radiation cross-linked UHMWPE. This study investigates the effects of radiation cross-linking and vitamin E incorporation on the dielectric behavior of UHMWPE. The dielectric relaxations of virgin and 0.1 wt % vitamin E-blended UHMWPE and their irradiated counterparts (up to 300 kGy dose) were investigated. To determine the effect of vitamin E content alone, vitamin E-loaded UHMWPEs were used. The results showed that radiation cross-linking and vitamin E content both increased dielectric polarization in UHMWPE and under some conditions induced electrical conductivity. This result is significant because it shows that the conductive response of UHMWPE-bearing surfaces may depend on manufacturing processes and additives, Research funded by the Comision Interministerial de Ciencia y Tecnologia (CICYT), Spain. Project MAT 2010-16175 from the Ministerio de Ciencia e Innovacion. The authors also acknowledge support from Project ENE2011-28735-C02-01 and Mr. Teruel Grant GRISOLIAP/2012/056.