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Silicon oxycarbide-based amorphous ceramic material was prepared by crosslinking and step-wise pyrolysis of polysiloxane-based Polyramic resin at temperatures up to 1200 °C as a matrix for anode in Na-ion batteries (NIBs). The synthesized powder was milled under low and high energy ball milling (LEM, HEM) conditions to investigate the effect of powder characteristics on the electrochemical properties of anodes in NIBs. The XPS and EDX analyses showed that the chemical compositions of anodes prepared from LEM and HEM SiOC were similar. However, the SiOC anodes prepared from finer grain sized HEM SiOC powders exhibited better performance like lower charge transfer resistance and faster Na+ diffusion coefficient. The slope capacity and thereby the total specific capacity was enhanced in HEM-SiOC anode. Therefore, the refinement of the particle size and increased surface area are vital for producing high-energy density SiOC anodes for NIBs. [ABSTRACT FROM AUTHOR]

Ethylene–propylene–diene monomer (EPDM)-based composites including four different types of graphene nanoplatelets (GnPs) were prepared to evaluate the size effects of GnPs in terms of both specific surface area and lateral size on the morphological, mechanical, and viscoelastic properties, swelling ratio, crosslink density, and oxygen permeability. EPDM-based hybrid composites with GnPs and carbon black (CB) fillers were prepared, with the concentrations of 20 and 50 phr of CB and GnPs up to 7 phr. All samples were prepared using the melt mixing method, followed by compression molding. The specific surface area of GnPs is a more important key factor for mechanical and viscoelastic properties than its lateral size. The presence of GnPs leads to a decrease in the swelling ratio and oxygen permeability of the matrix while an increase in the crosslinking density. For a given specific surface area of GnPs (170 m2/g) and the same thickness (5 nm), the optimum lateral size for mechanical properties, swelling ratio, and crosslinking density is about 30 µm. There is a distinct synergic effect on the mentioned properties when hybrid fillers are used. For hybrid composites, the optimum total and each filler concentration are found to be important for achieving the best performance in terms of mechanical properties, swelling ratio, and crosslink density. [ABSTRACT FROM AUTHOR]

The design of high-efficiency electrocatalysts for water electrolysis has attracted much attention. A crucial half-reaction in electrochemical water splitting is the oxygen evolution reaction (OER), which suffers from sluggish reaction kinetics due to the high-energy barrier of the complex electron transfer process. This study presents a MoSe 2 @CoAl-layered double hydroxide (LDH) hybrid nanostructure prepared using the facile hydrothermal method and investigated as a potential OER electrocatalyst. Morphological analysis indicated that the MoSe 2 formed in very thin nanosheet structures containing multiple defects on the LDH platelets, increasing the number of catalytic active sites. Compared with pristine MoSe 2 and CoAl-LDH, the obtained MoSe 2 @CoAl-LDH catalyst exhibited enhanced electrocatalytic activity for the OER in an alkaline solution. The MoSe 2 @CoAl-LDH electrocatalyst showed an overpotential of 360 mV at a current density of 10 mA cm−2 and a small Tafel slope of 53 mV dec−1. In addition, it demonstrated good electrochemical stability. The MoSe 2 @CoAl-LDH exhibited a lower Tafel slope than commercial RuO 2 , indicating faster electron transfer on the MoSe 2 @CoAl-LDH electrode. • MoSe 2 nanosheets were grown on the surface of CoAl-layered double hydroxide using hydrothermal method. • Hydrothermal synthesis resulted in the formation of defect sites on MoSe 2 @CoAl-LDH. • The MoSe 2 @CoAl-LDH hybrid nanostructure exhibits improved catalytic active sites. • The MoSe 2 @CoAl-LDH catalyst improved the performance of the oxygen evolution reaction in an alkaline solution. [ABSTRACT FROM AUTHOR]

Designing of high-performance, low-cost, and nonprecious metal-based bifunctional electrocatalysts is highly significant for the development of water splitting process and expanding the practical application of green hydrogen production. Transition metal dichalcogenides (TMDs) with intrinsic physical and chemical properties have been considered potential catalytic materials for electrode fabrication. However, it has remained challenging to develop TMD catalysts that have bifunctional properties for overall water splitting. Herein, WSe 2 , as a typical representative of TMDs, was utilized to design electrocatalysts using polypyrrole (PPy) or polyaniline (PANI) as a conducting polymer (CP) and cobalt doping. A facile hydrothermal preparation of WSe 2 in the presence of CP enabled the construction of cobalt-doped WSe 2 @CP electrocatalysts. Morphological analysis indicated that the CP played an important role as a conductive template to enhance the distribution of WSe 2 nanosheets, leading to higher surface area. In addition, cobalt doping led to the formation of defect structures and boosted the electrocatalytic activities of the catalysts for oxygen evolution reaction (OER). Owing to the increased electrochemical surface area and defect structures, the cobalt-doped WSe 2 @CP nanostructures exhibited enhanced electrochemical properties for hydrogen evolution reaction (HER) and OER in an alkaline medium. The cobalt-doped WSe 2 @PANI modified glassy carbon electrode (GCE) exhibited overpotentials down to 308 and 360 mV at a current density of 10 mA cm−2 for the HER and OER, respectively. Furthermore, the cobalt-doped WSe 2 @CP electrocatalysts demonstrated long-term stability and continuous cycling. More importantly, the Co–WSe 2 @PANI electrolyzer required cell voltage of 1.87 V at a current density of 10 mA cm−2 for overall water splitting process. This work provides new findings for designing efficient bifunctional electrocatalysts utilizing TMD materials and conducting polymers. [Display omitted] • Conducting polymer templated and cobalt-doped WSe 2 electrocatalysts were prepared. • Conducting polymers enhanced the catalytic performance of WSe 2 in water splitting. • Incorporation of cobalt enhanced the activity of WSe 2 for both HER and OER. • New WSe 2 -based catalysts have bifunctional activities for overal water splitting. [ABSTRACT FROM AUTHOR]

Polycaprolactone/polypyrrole (PCL/PPy) fibers were prepared using an original approach by electrospinning a mixing solution of PCL and pyrrole monomer as the first step. The presence of pyrrole monomer inside the electrospun fibers was confirmed by Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) analysis. Prepared fibers were immersed into the oxidizing agent solution containing pyrrole monomer and anionic surfactant surfactant – sodium 2-naphthalenesulfonate for polypyrrole coating at room temperature. The effect of preparation conditions was studied for the production of electrically conducting fabrics using various weight ratios of PCL to pyrrole monomer for fiber production. Various analytical methods were used to characterize the fibers before and after the polymerization. The presence of the polypyrrole coating on prepared PCL substructure was verified by Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and morphology analysis. The surface properties of the prepared conducting fibers were tested by contact angle measurement. The prepared nanofibers were homogenously coated with polypyrrole, and the samples containing at least 40 wt.% of pyrrole monomer after coating reached conductivity superior to 1 S/cm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stability of Ti 3 C 2 O x F x MXene in air and argon. • Combined XPS and TEM study, including electron diffraction. • Ti4+ state and TiO 2 formation during aging in air has been proved. • Proper storage of MXenes results in high stability in air (>337 days). Different batches of Ti 3 C 2 O x F x MXene were prepared, and their stability in air and argon was studied. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) in multiple modes (bright field imaging, energy-dispersive X-ray analysis, and selected-area electron diffraction) was employed to study the chemical and morphological changes in two-dimensional (2D) MXene exposed to air for several days and months. We observed the progressive development of the Ti4+ state accompanied by the development of TiO 2 formation, which lead to a slow disintegration of the 2D MXene nanosheets, although their overall morphology and crystalline structure can persist for several months. The presence of water is found to play an important role in the hydrolysis and degradation reactions during MXene aging. Our XPS and TEM studies show how the surface chemistry changes during aging in air and which surface termination groups are indicative of stable Ti 3 C 2 O x F x MXene and which storage conditions can stabilize MXene for more than 337 days. [ABSTRACT FROM AUTHOR]

Five different polypyrroles (PPys) with four different oxidants, namely, FeCl 3 , FeCl 3 ·6H 2 O, Fe 2 (SO 4 ) 3 , and (NH 4 ) 2 S 2 O 8 , were prepared by chemical oxidative polymerization and studied during aging. In the case of FeCl 3 , the anionic surfactant dodecylbenzenesulfonic acid (DBSA) was used as a co-dopant to improve the stability. The prepared PPys were aged (>400 days) in ambient air at a temperature of 24 ± 2 °C in our laboratory, where they were not directly exposed to the sun. A clear increase in the oxygen content could be seen on the surface of all the prepared samples. There was no significant difference between PPy prepared using FeCl 3 and FeCl 3 ·6H 2 O as oxidants. The incorporation of the anionic surfactant dodecylbenzenesulfonic acid into the PPy structure did not lead to a longer effective conjugation length but did lead to the superior stability of the prepared PPy in ambient air. PPy prepared with Fe 2 (SO 4 ) 3 and (NH 4 ) 2 S 2 O 8 showed inferior stability of electrical conductivity among the samples studied. The samples were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared spectroscopy (FTIR), and elemental analysis (EA), and the chemical changes during aging were confronted with measurements of the electrical conductivity. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes (CNT) were modified via the non-covalent approach using anodic surfactants dodecylbenzenesulfonic acid (DBSA) and poly(ethylene glycol) n-alkyl 3-sulfopropyl ether potassium salt and cationic surfactant cetyltrimethylammonium bromide (CTAB). These surfactants were used individually or as DBSA/CTAB mixtures. Surface modification was ultrasonically-assisted with a control over sonication power (64 or 360 W). The surface properties of modified CNT particles were determined by X-ray photoelectron spectroscopy and scanning electron microscopy. The electrical conductivities of unmodified CNT, particles treated by ultrasound, and CNT modified with surfactants were measured. Thermogravimetric analysis was used to determine the mass loading of surfactants after drying. The highest increase in conductivity was reached when CNT were treated solely with the anionic surfactant DBSA under the influence of soft ultrasound. This work shows conclusively that ultrasound-assisted modification of CNT by surfactants is a simple and efficient approach to prepare surface modified and highly conductive CNT, provided that physical (ultrasonic) and chemical (surfactants) treatments are concomitantly controlled. [ABSTRACT FROM AUTHOR]

The morphology and adhesive properties of waterborne films from n-butyl acrylate/methyl methacrylate/montmorillonite clay hybrid polymer latexes which were synthesized by miniemulsion polymerization in the presence of a reactive organoclay ((2-methacryloylethyl) hexadecyldimethylammonium modified montmorillonite, CMA16) were investigated. It was found by cryo-TEM analysis that the hybrid dispersions were a mixture of colloidal particles composed of a small fraction of free montmorillonite clay platelets, polymer latex particles, polymer particles to which one or more clay platelets where adhered onto its surface and a fraction of colloidal material consisted of a clay platelet with a polymer lob adhered to either side, in other words hybrid particles with a dumbbell-like morphology. The films made from these waterborne hybrid dispersions presented a homogeneous dispersion of the clay platelets and exfoliated morphology. The shear adhesion failure temperature (SAFT) and shear resistance of the hybrid latex films synthesized with CMA16 were better than those prepared with a commercial clay (Cloisite 30B), but presented a liquid-like probe-tack performance. When allyl methacrylate (AMA) was added in the formulation, SAFT and shear resistance improved, but the film had a very low energy of adhesion due to the excessively crosslinked matrix. In order to reduce crosslink density and thus improve the adhesion energy, small amounts of chain transfer agent, in this case n-dodecyl mercaptan (n-DDM), were used in the miniemulsion polymerization process. Adhesive films made from these waterborne hybrid dispersions showed excellent SAFT and shear resistance, and good energy of adhesion. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The nitroxide mediated controlled surface initiated polymerization of methyl methacrylate (MMA)/butyl acrylate (n-BA) was carried out with a macroinitiator modified montmorillonite. The macroinitiator was synthesized by the nitroxide mediated polymerization of vinylbenzyl trimethylammonium chloride (VBTMACl), methylmethacrylate (MMA) and styrene (S) at 90°C using BlocBuilder®. The macroinitiator was exchanged with the sodium cations of the montmorillonite, to yield surface modified reactive montmorillonite. The bulk polymerizations of BA/MMA from the clay surface produced controlled molecular weight polymers that were able to exfoliate the clay. This controlled polymer/clay nanocomposite was used as masterbatch and further dispersed in monomers and miniemulsified to perform miniemulsion polymerization of BA/MMA (90/10wt.%) at 30wt.% solids content at low emulsifier concentration. The adhesive properties of the nanocomposites prepared with the masterbatch were proved to be better than those prepared with an organically modified clay. [Copyright &y& Elsevier]

Abstract: Polypropylene (PP) and viscose (VS) textiles were modified by the in situ synthesis of a conducting polypyrrole (PPy) overlayer. To improve adhesion of the conducting layer to the textile surface, a pyrrole-functionalized silane (SP) was synthesized and bonded onto the surface before polypyrrole formation. Moreover, to introduce hydroxyl groups into the surface, PP was pretreated by grafting vinyltrimethoxysilane by means of a radiofrequency plasma discharge. The study is focused on the influence of SP on the washing fastness of a PPy layer and, consequently, on the overall conductivity of the textiles after washing. In the case of viscose, PPy was found to penetrate the substrate. A compromise was found between the influence of SP and penetration phenomenon (best conductivity after washing: wVS–0.2SP/25Py=3×10−5 S/square). In the case of polypropylene the effect of pretreatment with SP is much better than for viscose, and a higher concentration of SP leads to improved fastness of the conductive layer (wmPP–0.2SP/25Py=3×10−5 S/square; wmPP–1SP/25Py=8×10−5 S/square), which indicates that the coating promoted by means of SP is more favoured than for viscose. [Copyright &y& Elsevier]

Abstract: Polypyrrole was chemically synthesized by oxidative polymerization of pyrrole in aqueous solution of ferric sulfate, and an anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT). At low AOT loading, this anion acts essentially as a co-dopant of polypyrrole (PPy) chains, whereas at high loading it not only co-dopes PPy in the bulk of the particles, but acts also as a surfactant as proved by X-ray photoelectron spectroscopy (XPS) and inverse gas chromatography (IGC). The surface energy of the powder specimens was determined by IGC. At 30°C, the dispersive contribution to the surface energy () decreased from 62.9 for sulfate-doped polypyrrole to 36.6mJ/m2 for a polypyrrole with the highest AOT loading. This minimization of the surface energy was found to be beneficial for the dispersion of polypyrrole and the formation of conductive paths in a host polypropylene matrix, as judged from transmission electron micrographs. Moreover, the examination by scanning electron microscopy (SEM) of the fracture surface of polypyrrole-filled polypropylene indicated a better wetting of the AOT-containing polypyrrole by the polypropylene matrix compared to the pure polypyrrole powder particles. The results are interpreted in terms of minimization of the polypropylene–polypyrrole interfacial tension. [Copyright &y& Elsevier]

Abstract: New types of composites were prepared using low-density polyethylene (LDPE) filled with modified organic filler, Canadian switch grass coated with polypyrrole (PPy). The grass surface was entirely covered when 10wt.% of pyrrole was used for the modification, as confirmed by scanning electron microscopy and infrared spectroscopy. LDPE composites filled with modified grass were prepared by melt mixing and their properties were compared with the properties of the composites filled with unmodified grass. The influence of crosslinking, induced by 1wt.% of peroxide, on mechanical, thermal and electrical properties of the composites was investigated. Crosslinking enhanced the tensile strength of the prepared composites in the entire range of the filler content. The Young’s modulus of the composites prepared by crosslinking is slightly lowered when compared with the uncrosslinked composites if the filler content is less than 60wt.%, for higher filler content it is increased. The conductivity of the uncrosslinked composites containing 40wt.% of grass modified by PPy was in the range 1×10−6 Scm−1, which is a value by 5 orders of magnitude higher than the conductivity of the crosslinked materials. The presence of PPy on grass surface leads to a reduction of crosslinking of the LDPE matrix. [Copyright &y& Elsevier]

The surface-enhanced Raman scattering (SERS) properties of low-dimensional semiconducting MXene nanoflakes have been investigated over the last decade. Despite this fact, the relationship between the surface characteristics and SERSing performance of a MXene layer has yet to be comprehensively investigated and elucidated. This work shows the importance of surface morphology on the overall SERS effect by studying few-layer Ti3C2Tx MXene-based SERS substrates fabricated by vacuum-assisted filtration (VAF) and spray coating on filter paper. The VAF deposition results in a dense MXene layer suitable for SERS with high spot-to-spot and substrate-to-substrate reproducibility, with a significant limit of detection (LoD) of 20 nM for Rhodamine B analyte. The spray-coated MXenes film revealed lower uniformity, with a LoD of 50 nM for drop-casted analytes. Moreover, we concluded that the distribution of the analyte deposited onto the MXene layer is affected by the presence of MXene aggregates created during the deposition of the MXene layer. Accumulation of the analyte molecules in the vicinity of MXene aggregates was observed for drop-casted deposition of the analyte, which affects the resulting SERS enhancement. Ti3C2Tx MXene layers deposited on filter paper by VAF offer great potential as a cost-effective, easy-to-manufacture, yet robust, platform for sensing applications. [ABSTRACT FROM AUTHOR]

The active surface of the 3D nickel foam electrodes was prepared by electrodeposition. Nickel-based metallic nanocoatings were deposited on pure nickel foam. Optimum parameters of the electrodeposition were found using the central composite rotatable design optimisation method. Pure nickel foam, electrodeposited nickel, and Ni–W coatings on the foam were tested for the load and stability measurements by zero-gap alkaline water electrolysis. It was found that Ni–W surface layer was superior to the nickel coating. This can be explained by a higher amount of active sites due to W content. [ABSTRACT FROM AUTHOR]

Composite materials of BEA zeolite and polyaniline (PANI) were prepared by the chemical oxidative polymerization of aniline in the presence of zeolite in water (without added acid) and in an aqueous solution of sulfuric acid, using ammonium peroxydisulfate as an oxidant. Protonated (as-synthesized) and deprotonated forms of the composites and pristine PANIs were characterized by scanning electron microscopy, conductivity and zeta potential measurements, FTIR, Raman and XPS spectroscopies, and thermogravimetric analysis. Adsorption properties of synthesized materials for removal of nicosulfuron pesticide from aqueous solutions were studied, using HPLC technique. The obtained adsorption isotherms were analyzed using Freundlich and Langmuir-Freundlich equations. Protonated PANI/BEA composites showed excellent adsorption capacity (18.4–25.4 mg g−1), that was higher than the adsorption capacity of pristine BEA zeolite (18.2 mg g−1) but slightly less than neat PANI. Among PANIs, the highest adsorption capacity of 29.8 mg g−1 of adsorbent was found for protonated PANI prepared in sulfuric acid solution. Analysis of adsorption isotherms revealed high degree of surface homogeneity for all prepared composite materials and PANIs. Proposed mechanism for enhanced adsorption of nicosulfuron on protonated composites is based on hydrogen bonding of nicosulfuron O- and N-containing groups with bridging hydroxyls of BEA zeolite and –NH/ = NH+/−NH • + groups in protonated emeraldine salt form of PANI chains (PANI-ES), accompanied with electrostatic attractive interaction between anionic nicosulfuron species and positive = NH+/−NH • + groups in bipolaron/polaron containing structures of PANI-ES. Presence of protons in bridging hydroxyls in BEA zeolite and in protonated PANI-ES chains is essential for excellent adsorption of nicosulfuron via hydrogen bonding on all protonated composite samples. In support of this interpretation, deprotonated PANI/BEA composites and deprotonated PANIs showed significantly lower adsorption capacities (in the range 5.5–13.0 mg g−1) compared to those of their protonated counterparts. Image 1 • Polyaniline/BEA zeolite composites were synthesized with and without added acid. • Protonated composites are enhanced adsorbents when compared to BEA zeolite. • Protonated polyanilines demonstrated the highest adsorption of nicosulfuron. • Proposed mechanism for nicosulfuron adsorption is based on hydrogen bonding. [ABSTRACT FROM AUTHOR]

[Display omitted] • MoSe 2 catalysts were prepared in the presence of polyaniline and simultaneously doped with three different transition (Co, Ni, or Fe) metals. • Incorporation of conductive polyaniline and transition metal doping enhanced the active sites of MoSe 2 for electrochemical water splitting. • Co-doped MoSe 2 @PANI catalyst exhibited overpotentials of 196 mV and 385 mV at a current density of 10 mA cm−2 for HER and OER, respectively. • Co-doped MoSe 2 @PANI could help to future design of low-cost and high-performance bifunctional catalysts for overall water splitting. Transition metal dichalcogenides (TMDs) are potential candidates for electrocatalytic applications due to their unique structures and intrinsic properties. In this work, the systematic synthesis of conducting polymer-templated and nonnoble metal-doped MoSe 2 hybrids was carried out using a facile hydrothermal method. Integrating conductive polyaniline, as a conductive polymer, with MoSe 2 nanosheets (MoSe 2 @PANI) as well as transition metal (Co, Ni or Fe) doping provided more active sites for both H+ and OH– adsorption, resulting in enhanced hydrogen and oxygen evolution performance. The Co-doped MoSe 2 @PANI hybrid catalyst exhibited enhanced bifunctional electrocatalytic activity for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in alkaline electrolytes, where Co-doping as well as polyaniline addition played key roles in boosting the HER/OER activity. As a result, the Co-doped MoSe 2 @PANI catalyst exhibited overpotentials of 196 mV and 385 mV at a current density of 10 mA cm−2 for the HER and OER, respectively. When Co-doped MoSe 2 @PANI was applied as a bifunctional electrocatalyst for overall water splitting, a potential of 1.82 V was needed to achieve a current density of 10 mA cm−2. Moreover, the Co-doped MoSe 2 @PANI catalyst displayed good stability for long-term cycling. This work provides new insight into the design of metal-doped TMD/conducting polymer-based materials for electrocatalytic applications, including water electrolysis. [ABSTRACT FROM AUTHOR]

Investigation was made into the effect of plasma treatment on the release kinetics of the drug Temozolomide (TMZ) from thin, biodegradable polyester films, comprising polylactic acid (PLA) and polyester urethane. The authors utilized two systems to achieve this, the first being diffuse coplanar surface barrier discharge, applying air as the gaseous medium, while the other involved capacitively coupled radio frequency discharge plasma under an argon atmosphere with hexamethyldisiloxane. Results showed that both forms of plasma treatment positively reduced the undesirable burst effect and benefited the release rate of TMZ. The hydrolytic degradability of the materials was slightly enhanced following hydrophilization, whereas the same diminished after hydrophobization had taken place. This was especially true for PLA due to modification of its wettability. [ABSTRACT FROM AUTHOR]

Simple and robust methods for modifying hydrophobic polymer surfaces with zwitterionic polymers using UV irradiation were developed. Two random zwitterionic copolymers consisting of either carboxybetaine or sulfobetaine methacrylamide monomers and monomers bearing a photolabile azidophenyl group were directly photoimmobilized on polymeric surfaces (polyester, polyethylene and polystyrene) via covalent interactions in a spatially controlled manner. These copolymers were also electrospun to form self-standing mats. The modified surfaces were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, infrared spectroscopy and contact angle measurements. The electrospinning method involved the use of a trifluoroethanol solution with a copolymer concentration in the range from 2 to 10 wt.%. BHK 21 cell adhesion to both modified surfaces and mats was dramatically reduced compared to unmodified surfaces. [ABSTRACT FROM AUTHOR]

Heavily oxidized and ordered graphene nanoplatelets were produced from natural graphite by oxidation using a mixture of phosphoric acid, sulphuric acid, and potassium permanganate (Marcano's method). The atomic percentage of oxygen in the graphite oxide produced was more than 30% confirmed by XPS studies. The graphite oxide produced had intact basal planes and remains in a layered structure with interlayer distance of 0.8 nm, analyzed by WAXS. The graphite oxide was treated with 4,4′-methylenebis(phenyl isocyanate) (MDI) to produce grafted isocyanate functionalization. Introduction of these bulky functional groups widens the interlayer distance to 1.3 nm. In addition, two reduction methods, namely benzyl alcohol mediated reduction and thermal reduction were carried out on isocyanate modified and unmodified graphite oxides and compared to each other. The decrease in the oxygen content and the sp 3 defect-repair were studied with XPS and RAMAN spectroscopy. Compared to the thermal reduction process, which is connected with large material loss, the benzyl alcohol mediated reduction process is highly effective in defect repair. This resulted in an increase of conductivity of at least 9 orders of magnitude compared to the graphite oxide. [ABSTRACT FROM AUTHOR]

[Display omitted] One of the highlighted properties of Ti 3 C 2 T x MXene compared to other 2D nanomaterials is its hydrophilicity. However, the broad range of static contact angles of Ti 3 C 2 T x reported in the literature is misleading. To elucidate the experimental values of the static contact angles and get reproducible contact angle data, it is wiser to perform the advancing and receding contact angle measurements on smooth and compact Ti 3 C 2 T x layers and focus on deep understanding of the physical basis behind the wettability, which is provided by contact angle hysteresis. Measurements of the advancing and receding contact angle on mono-, bi, and trilayer Ti 3 C 2 T x on two different substrates were performed. As substrates, UV-ozone treated silicon wafer and silicon wafer functionalized by (3-aminopropyl)triethoxysilane, were used. The values of the advancing contact angle on Ti 3 C 2 T x on both substrates were proved to be independent of the number of Ti 3 C 2 T x layers, demonstrating a negligible effect of the background substrate wettability. In addition, a giant contact angle hysteresis (44–52 °) was observed on very smooth surface, most likely as a result of chemical heterogeneity arising from the diversity of surface terminal groups (F, O, and OH). The findings reported in this study provide a comprehensive understanding of the wettability of MXene. [ABSTRACT FROM AUTHOR]

New mixed-cation fluorides KNa 2 HfF 7 (Pmn 2 1 , a = 8.213(2) Å, b = 6.126(2) Å, c = 5.979(2) Å, Z = 2) and KNa 2 (Hf,Zr)F 7 (refined composition KNa 2 Hf 0.44(1) Zr 0.56(1) F 7 ; Pmn 2 1 , a = 8.2210(8) Å, b = 6.1288(6) Å, c = 5.979(1) Å, Z = 2) together with isostructural KNa 2 ZrF 7 (Pmn 2 1 , a = 8.221(2) Å, b = 6.118(2) Å, c = 5.994(2) Å, Z = 2) have been synthesised in aqueous solutions and structurally characterised at room temperature by powder and single-crystal X-ray diffraction. The solid-solid phase transformations have been revealed during the differential scanning calorimetry experiments and further confirmed by temperature-dependent X-ray powder diffraction. It has been found that mixed-cation phases KNa 2 ZrF 7 , KNa 2 HfF 7 and KNa 2 (Hf,Zr)F 7 undergo irreversible phase transformations, which can be explained by their decomposition over 673 K. XPS analysis confirmed the presence of exclusively terminated fluorines around the transition metals and the absence of oxygen impurities in the crystal structures of compounds. Crystal structure and thermal behaviour of KNa 2 HfF 7 – a typical representative of the mixed-cation A 3 M F 7 compounds (A = Na, K; M = Zr, Hf, Hf/Zr) that undergo the irreversible phase transformations due to the decomposition over 673 K. [Display omitted] • New mixed-cation fluorides KNa 2 HfF 7 and KNa 2 (Hf,Zr)F 7 have been synthesised. • KNa 2 HfF 7 and KNa 2 (Hf,Zr)F 7 are found to be isostructural to KNa 2 ZrF 7. • KNa 2 HfF 7 is characterised by the disordered position of some fluorine atoms. • KNa 2 ZrF 7 , KNa 2 HfF 7 , KNa 2 (Hf,Zr)F 7 undergo the irreversible phase transformations. • XPS analysis confirmed the presence of terminally bonded fluorines around Zr and Hf. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Younǵs modulus of the composites increased 13times. [•] The flexural strength of composites was improved 2 times. [•] The polarity of LDPE was significantly enhanced. [•] The adhesion of composites to the polar substrates was improved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface initiated photoATRP was optimized to achieve high thickness of brushes. • High fidelity of the polymer chain-ends was proven by grafting multiblock chains. • Versatility of the conditions was demonstrated on 3 types of hydrophilic monomers. • Antifouling properties were improved with thickness of the PHEMA brushes. The recent development of sustainable chemistry motivates scientists to develop economically favourable, highly efficient, and environmentally friendly polymerization techniques. This contribution demonstrates a facile fabrication of hydrophilic polymer brushes via surface-initiated photochemically induced atom transfer radical polymerization using a copper catalyst in low concentrations and microlitre volume of polymerization mixture (SI-μL-CuPhotoATRP). The fabrication proceeds by sandwiching of μL reaction solution between a Si-wafer modified with ATRP-initiator and a glass slide under atmospheric and ambient conditions. Optimization of reaction conditions was realized on hydrophilic monomer such as 2-hydroxyethyl methacrylate (HEMA). Effect of various experimental parameters such as light intensity, solvents, ligands, the volume of the reaction solution, size of the Si-wafers, amount of CuBr 2 , and CuBr 2 /ligand ratio in kinetics, linear increase of polymer layer thickness, final thickness and profile of unmodified edges were investigated. The successful fabrication of hydrophilic polymer brushes is confirmed via Fourier transfer infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), profilometry and water contact angle. A linear thickness increase with time up to at least 300 nm was achieved, compared to polymethacrylate layers with thickness up to approximately 100 nm previously published by using photoATRP. The general applicability of the optimized conditions for SI-μL-CuPhotoATRP was further proved for two additional hydrophilic monomers, such as glycidyl methacrylate and 2-hydroxypropyl methacrylate. Furthermore, sequential homo and block copolymerization demonstrated the living character of fabrication conditions, permitting facile fabrication of well-controlled tetra block homo/copolymer brushes with a pyramid-like pattern on Si-wafer. Poly(2-hydroxyethyl methacrylate) (PHEMA) brushes-grown surfaces exhibit excellent antifouling properties and long-term structural stability. The facile, affordable, and environmentally friendly SI-μL-CuPhotoATRP approach provides avenues for various surface modifications, such as biomedical, soft robotic, and coating applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanoporous black gold films enable efficient hydrogen sensing at low temperatures (40 °C). • Fast response and recovery times (0.5 - 1 min) make them promising for practical use. • Nanoporous morphology enhances gas permeation and sensor sensitivity. Hydrogen sensing is a crucial topic for many industrial and environmental applications regarding the green deal and the use of hydrogen as a next-generation energy source/energy-storage medium. Therefore, many different approaches are being used to find sensitive, reliable and inexpensive devices for hydrogen detection. One such approach is the use of chemiresistive nanostructured materials that provide a large surface area for hydrogen adsorption. In this paper, we present a detailed study of the hydrogen sensing capabilities of highly nanoporous black gold films that show fast response and recovery times (0.5 min) while operating at low temperatures (40 °C). To investigate the sensing properties of black gold, films with different levels of nanoporosity were prepared and tested to a hydrogen concentration in the range of 0.25–0.95 %. Film morphology was characterised by AFM, SEM and XPS. To correctly examine the nanopores and defects in prepared films, Variable Energy Positron Annihilation Spectroscopy (VEPAS) was used. We found that nanoporous black gold is suitable as an active layer of chemiresistor for hydrogen sensing and that its sensitivity is the function of the film nanoporosity. Possible mechanisms of hydrogen-gold interactions are discussed. [ABSTRACT FROM AUTHOR]

Industrially important properties of wood can be changed due to the modification of birch wood (Betula pendula L.) after the process of thermal treatment with saturated water steam. The birch wood was modified by saturated water steam at 125 ± 2.5 °C for 8 hours and at a pressure of 0.18 MPa. The water contact angle of steam-treated birch wood increased from 42.1° (for untreated birch wood) to 52.4° (for steam-treated birch wood), and the stability of water drop on steam-treated birch wood surface increased. FTIR spectra showed an increase in C=O and glycoside bonds concentration on the surface of steam-treated birch wood, but the concentration of C-O-C groups decreased. XPS measurements confirmed that the concentration of oxygen as well as C=O and C-O-O groups on the surface of steamtreated birch wood showed an increment in comparison with the native wood sample. SEM micro photos confirmed the minor changes of birch wood cells due to the action of saturated water steam modification. [ABSTRACT FROM AUTHOR]

Abstract: While systems K3TaF8 and K3ZrF7 were prepared by modified molten salt method modified wet pathway was used for reproducible preparation of Na7Zr6F31. Its congruently melting character was demonstrated on simultaneous TG/DSC measurements and XRD patterns. X-ray photoelectron spectroscopy was applied for identification of differently bonded fluorine atoms in series of compounds NaF, K2TaF7, K3TaF8, K2ZrF6, Na7Zr6F31 and K3ZrF7. Three different types of fluorine atoms were described qualitatively and quantitatively. Uncoordinated fluorine atoms (F−) provide signals at lowest binding energies, followed by signals from terminally coordinated fluorine atoms (M–F) and then bridging fluorine atoms (M–F–M) at highest energy. Based on XPS F 1s signals assigned to fluorine atoms in compounds with correctly determined structure it was suggested that fluorine atoms in K3ZrF7 have partially bridging character. [Copyright &y& Elsevier]

Poly(lactide) (PLA) films obtained by thermoforming or solution-casting were modified by diffuse coplanar surface barrier discharge plasma (300 W and 60 s). PLA films were used as hot-melt adhesive in joints in oak wood. It was demonstrated that lap shear strength increased from 3.4 to 8.2 MPa, respectively, for the untreated and plasma-treated series. Pull-off tests performed on particleboard for the untreated and treated PLA films showed 100% cohesive failure. Pull-off strength tests on solid oak demonstrated adhesion enhancement from 3.3 MPa with the adhesion failure mode to 6.6 MPa with the cohesion failure mode for untreated and treated PLA. XPS revealed that carbonyl oxygen content increased by two-to-three-fold, which was confirmed in the Fourier-transform infrared spectroscopy experiments of the treated PLA. The water contact angle decreased from 66.4° for the pristine PLA to 49.8° after treatment. Subsequently, the surface free energy increased from 47.9 to 61.05 mJ/m2. Thus, it was clearly proven that discharge air plasma can be an efficient tool to change surface properties and to strengthen adhesive interactions between PLA and woody substrates. [ABSTRACT FROM AUTHOR]

N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan salt (HTCS) is used in applications benefiting from its strong cationic charge. The degree of quaternization (DQ) and the type of counterions are the HTCS fundamental characteristics. HTCS with DQ between 15 and 116% were synthesized by reaction between chitosan glucosamine unit and glycidyltrimethylammonium chloride. While this should lead to a chloride polysalt, we unexpectedly identified a massive spontaneous exchange of chloride counterions by other anions originated from aqueous environment during synthesis and purification. Up to 70% lower DQ was obtained by potentiometric titration of chloride counterions – the method widely used in literature. It was shown that the true DQ can be determined by NMR spectroscopy. The phenomenon of counterion exchange was further verified by XPS and demonstrated also for quaternized dextran. The underlying mechanism of the counterion exchange was explained. It should be considered for other polyelectrolytes especially in applications, where the counterion type is important. [Display omitted] • A comprehensive approach to synthesis and characterization of quaternized chitosan. • A true degree of quaternization is determined by 1H NMR. • A titration of chloride ions provides only an apparent degree of quaternization. • There is a massive chloride counterions exchange in the aqueous solution. • A mechanism responsible for the counterion exchange by other anions is described. [ABSTRACT FROM AUTHOR]

Gel filtration is a versatile technique employed for biological molecules and nanoparticles, offering their reproducible classification based on size and shape. Colloidal nanoparticles are of significant interest in biomedical applications due to a large number of solution-based bioconjugation procedures. Nevertheless, the inherent polydispersity of the nanoparticles produced by various techniques necessitates the employment of high yield separation and purification techniques. Here we demonstrate the employment of gel filtration on non-stoichiometric plasmonic MoOx nanoparticles, prepared by an oxidation process during liquid-phase exfoliation of few-layer MoS2 nanosheets. This resulted in the separation of two types of MoOx particles, in the form of two different chromatographic fractions. They showed different sizes, morphological and optical properties. The fraction containing smaller particles with diameters of 1–4 nm, exhibited an increased absorbance peak in the near IR region and responded with a significant temperature increase to laser irradiation at the wavelength close to the maximal absorption. The fraction with the larger particles from 3 up to 10 nm, showed weak photoluminescence and a preferred orientation upon the deposition on a planar substrate. However, it had no absorbance in the near IR compared to the former fraction. According to our knowledge, this is the first time that the gel filtration was applied to the separation of molybdenum oxide nanomaterials. This step ensured the isolation of plasmonic MoOx nanoparticles suitable for further bioconjugation and target photothermal treatment. [ABSTRACT FROM AUTHOR]

The study demonstrates that resistivity of an alumina wafer is highly sensitive to trace concentrations of acetone vapors at room temperature. Though, a thermal pretreatment is necessary to precede the room-temperature sensing of acetone vapors, whilst the sensitiveness increases with the pretreatment temperature. This advocates the alumina being suitable for an adequate acetone sensor in the ppm range. A plausible mechanism of the response is discussed. [ABSTRACT FROM AUTHOR]

A conducting polymer, polypyrrole, was deposited on tungsten disulfide flakes in situ during the oxidation of pyrrole. The conductivity of composites exceeded the conductivities of the parent components. This synergistic effect is explained by the deposition of more conducting ordered polypyrrole at first, and less conducting globular polypyrrole later after the whole available tungsten disulfide surface was coated. Such scenario was confirmed by electron microscopies. Raman and X-ray photoelectron spectroscopies proved the completeness of the coating. Despite the increase in the conductivity, the electrocatalysis of hydrogen evolution reaction on tungsten disulfide was reduced after polypyrrole deposition, confirming also effective coating of the substrate. A simple mixture of both components, however, improved the electrocatalytic effect compared with the composite or any of its components. Unlabelled Image • Composites of tungsten disulfide and conducting polymer were prepared. • Tungsten disulfide coated with polypyrrole has higher conductivity than components. • Polymer chain ordering is crucial for the understanding of conductivity behaviour. • Electrocatalytic activity in hydrogen evolution reaction has been investigated. • A mixture of disulfide and polypyrrole performed better than any component alone. [ABSTRACT FROM AUTHOR]

By using methyl orange template, polypyrrole nanotubes were obtained by the oxidative polymerization of pyrrole. The nanotubes were carbonized in inert atmosphere to nitrogen-enriched carbon nanotubes. These were subsequently coated with 20 wt% of polypyrrole prepared in the absence or the presence of anionic dyes (methyl orange or Acid Blue 25). The morphology of all the samples was examined by the electron microscopies, FTIR and Raman spectroscopies. Moreover, X-ray photoelectron spectroscopy and elemental analysis were used to prove the chemical structure and the successful coating process. Electron paramagnetic resonance analysis was used to calculate the spin concentrations. Significant impact of coating method is evidenced with neat polypyrrole coating providing a two-fold capacitance increase compared to uncoated nanotubes, while coating in the presence of Acid Blue 25 decreasing it slightly. With respect to oxygen reduction reaction, coatings irreversibly transformed in the first few cycles in the presence of the products of O 2 reduction, presumably hydrogen peroxide, altering the oxygen reduction mechanism. This transformation allows the tailoring of the polymeric shell, over ORR active carbonaceous core, and tuning of the catalyst selectivity and optimization of materials performance for a given application – from alkaline fuel cells to hydrogen peroxide generation. [ABSTRACT FROM AUTHOR]

Diagnosis of oncological diseases remains at the forefront of current medical research. Carbonic Anhydrase IX (CA IX) is a cell surface hypoxia-inducible enzyme functionally involved in adaptation to acidosis that is expressed in aggressive tumors; hence, it can be used as a tumor biomarker. Herein, we propose a nanoscale graphene oxide (GO) platform functionalized with magnetic nanoparticles and a monoclonal antibody specific to the CA IX marker. The GO platforms were prepared by a modified Hummers and Offeman method from exfoliated graphite after several centrifugation and ultrasonication cycles. The magnetic nanoparticles were prepared by a chemical precipitation method and subsequently modified. Basic characterization of GO, such as the degree of oxidation, nanoparticle size and exfoliation, were determined by physical and chemical analysis, including X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and atomic force microscopy (AFM). In addition, the size and properties of the poly-L-lysine-modified magnetic nanoparticles were characterized. The antibody specific to CA IX was linked via an amidic bond to the poly-L-lysine modified magnetic nanoparticles, which were conjugated to GO platform again via an amidic bond. The prepared GO-based platform with magnetic nanoparticles combined with a biosensing antibody element was used for a hypoxic cancer cell targeting study based on immunofluorescence. [ABSTRACT FROM AUTHOR]

Nanocomposites, based on an ethylene vinyl acetate (EVA) copolymer with a vinyl acetate content of 34 wt % and varying amounts of multiwall carbon nanotubes (MWCNTs), were prepared by an electrospinning method. The dispersibility of the MWCNTs in the solution was improved by using cholesteryl 1-pyrenecarboxylate (PyChol) as a compatibilizer. The transmission electron microscopy images showed that the MWCNTs were aligned inside of the elastomeric matrix by the electrospinning process. The morphologies of the fibers were evaluated by scanning electron microscopy. When the amount of MWCNTs in the polymer solution reached 3 wt %, fibers with a diameter of 846 ± 447 nm were prepared. The chemical composition of the prepared fibers was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). FTIR results confirmed the presence of a carboxyl group, originating from the presence of PyChol. XPS results showed that the EVA fibers produced by electrospinning were oxidized in ethylene units, when comparing the spectra of the original EVA granules, but the presence of MWCNTs enhanced the stability of the EVA. The thermal stabilities of the fibers were tested with thermogravimetric analysis. The results confirmed that the presence of MWCNTs inside the fibers enhanced the thermal stabilities of the prepared nanocomposites. [ABSTRACT FROM AUTHOR]

Abstract Due to their high stability over a wide range of temperature or moisture, silicone-based dielectric elastomer transducers (DETs) are of great scientific interest. In this regard, highly stretchable silicone elastomer films were prepared on the basis of a high molecular weight (Mn = 380,000 gmol−1) polydimethylsiloxane‑α,ω‑diol (PDMS) and stabilized by condensation crosslinking at room temperature, process which was monitored by IR spectroscopy. The obtained films were treated in oxygen radio-frequency (RF) plasma at 50 and 60 W for 3, 6 and 12 min. Depending on plasma treatment conditions, different surface morphologies were obtained, as evidenced by the atomic force microscopy (AFM), while chemical modifications were investigated by X-ray photoelectron spectroscopy (XPS). The elastomer films activated on both sides were further used as substrate for silver electrode deposition through Pulsed Laser Deposition (PLD) to obtain DETs. The deposited films were investigated from the point of view of mechanical and electrical behavior in normal state and after repeated mechanical stresses to assess the suitability of silver layer as stretchable electrode. Moreover, the achieved DETs were successfully tested in terms of actuation displacement. Graphical abstract Unlabelled Image Highlights • Silicone film is prepared and used as substrate for Pulsed Laser Deposition of Ag. • The advance of polydimethylsiloxane crosslinking is monitored by IR spectroscopy. • To ensure good compliance, Ag electrode is deposited on plasma treated silicone film. • Ag‑silicone-Ag layers array is obtained as a dielectric elastomer transducer (DET). • The surface, electrical, mechanical and electromechanical behavior of DETs are analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report of employing the electron beam irradiation for preparation of poly(2-oxazoline)-based hydrogel coatings. • Applied method is independent on surface material (Si wafer, PS plate). • Grafting and crosslinking are driven by amount of double bonds essential for the formation of covalent bonds. • Presence of the hydrogel layer decreases cell adhesion to a negligible value. • The stiffness increases with the degree of crosslinking which denotes the possibility of adjusting the required stiffness by proper selection of the experimental parameters. Uncontrolled accumulation of proteins and cells on implantable materials often leads to failure of their performance in vivo. The idea presented in this paper is the use of electron beam irradiation as a widely applicable, cost-effective, and defined method to produce non-biofouling hydrogel coatings to improve the biocompatibility and in vivo performance of implantable materials. Statistical copolymers poly[2-methyl-2-oxazoline-co-2-(3-butenyl)-2-oxazoline]s were deposited on different substrates and irradiated with beta radiation of different radiation doses (2–100 kGy). In the bulk state experiments, we found that the higher content of crosslinkable 3-butenyl units and a higher radiation dose resulted in more efficient crosslinking. Similarly, the irradiation of coatings demonstrated the high impact of the concentration of 3-butenyl units on crosslinking efficiency. Accordingly, the concentration of crosslinkable double bonds in the copolymer is crucial for the stability and homogeneity of the formed hydrogel layer. Stable and uniform hydrogel layers with thicknesses in the micrometer range were prepared from a 5 wt% copolymer solution. Depending on the preparation conditions, the hydrogel layers showed excellent non-biofouling properties with a low number of adherent cells. In addition, stiffness was dependent on the degree of crosslinking, and can thus be tailored for specific application in living tissue. [ABSTRACT FROM AUTHOR]

Lignin/polypyrrole composites were prepared by single-step coating of water-insoluble kraft lignin with polypyrrole. The polymerization of pyrrole was performed with and without the presence of methyl orange, leading to the formation of polypyrrole films of two different morphologies, globular and nanotubular, respectively, on the lignin surface. Such composites were converted to double-carbon composites enriched in inert atoms by pyrolysis in nitrogen atmosphere at 650 °C. The carbonization process was followed by thermogravimetric analysis and confirmed by Raman spectroscopy. The properties of all composites were investigated by FTIR spectroscopy, XPS, EPR, SEM, specific surface area and electrical conductivity measurements. Electrochemical properties were analyzed in terms of their capacitive behavior mainly in acidic solutions, but also in neutral and alkaline media. [ABSTRACT FROM AUTHOR]

Microfibrillated cellulose (MFC) has recently been identified as an innovative product of wood and agriculture industry with potential applications as reinforcement and carrier for functional properties of polymer composite materials, such as improved barrier and optical properties. The widespread commercial application of MFC in polymer technology still requires the development of new methods of MFC surface modifications in order to provide stong interfacial adhesion and good dispersibility of additive in polymer matrix. In this work microfibrillated cellulose was modified by acid chlorides arranged in a homologous series that showed high efficiency in changing the surface properties of the material. The modified MFC displayed hydrophobic character combined with preserved fibrillar morphology and high crystallinity. Chemical modification of MFC was assessed by Fourier transformed infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses. Despite the fact that the reactivity of acid chloride slightly decreased with increasing chain length the total effect on MFC wetting with water was most pronounced for the modifier with the longest alkyl chain. Completely bio-based engineering nanocomposites of biopolyamide 4.10 (PA4.10) and surface modified MFC were prepared by melt blending. Structural, morphological and thermomechanical analysis by scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic mechanical analysis (DMA) methods evidenced clear dependence of composite performance on the length of alkyl chain attached to the MFC surface. The modification of MFC by hexanoyl chloride produced nanofiller with good dispersibility in PA4.10 matrix and was favorable in terms of dynamic mechanical properties of composites. While PA4.10 composites containing MFC functionalized by longer alkyl chains (more than 10 carbon atoms) showed a decrease of storage modulus due to insufficient interfacial interactions or plasticization effect. [ABSTRACT FROM AUTHOR]

Extended information is provided about 19 F MAS NMR and XPS spectroscopic data on 11 ternary fluorido-zirconates (Li 2 ZrF 6 , Rb 2 ZrF 6 , Cs 2 ZrF 6 , Na 3 ZrF 7 , (NH 4 ) 3 ZrF 7 , K 3 ZrF 7 , Li 4 ZrF 8 , K 2 ZrF 6 , Na 5 Zr 2 F 13 , Na 7 Zr 6 F 31 , and (NH 4 ) 2 ZrF 6 ), which display different coordination numbers of the zirconium atom as well as different modes of fluorine atom bonding. XPS data show that binding energies on fluorine 1s electrons are sensitive to its coordination properties (ionic, terminal or bridging coordination mode) while the binding energies of zirconium orbitals are not sensitive to its coordination properties (six-, seven- or eightfold coordination). 19 F chemical shifts correlate with the ionic radii of counter cations along the series Li 2 ZrF 6 , Rb 2 ZrF 6 , Cs 2 ZrF 6 and K 3 ZrF 7 , (NH 4 ) 3 ZrF 7 and Na 3 ZrF 7 . This reflects the polarizability properties and shielding potential of the cations surrounding the fluorine atoms. Additionally, calculations of NMR parameters for the compounds were also carried out using the CASTEP DFT code. The correlation between the experimental isotropic chemical shifts and calculated isotropic chemical shieldings established for the studied compounds allows us to predict the 19 F NMR spectrum of crystalline compounds with good accuracy. A unique technique of low temperature 19 F MAS NMR experiments combined with CASTEP calculation on (NH 4 ) 2 ZrF 6 enabled the assignment of all 12 crystallographically non-equivalent fluorine atoms to NMR signals. [ABSTRACT FROM AUTHOR]

This work is the first report that critically reviews the properties of layered double hydroxides (LDHs) on the level of speciation in the context of water treatment application and dynamic adsorption conditions, as well as the first report to associate these properties with the synthetic methods used for LDH preparation. Increasingly stronger maximum allowable concentrations (MAC) of various contaminants in drinking water and liquid foodstuffs require regular upgrades of purification technologies, which might also be useful in the extraction of valuable substances for reuse in accordance with modern sustainability strategies. Adsorption is the main separation technology that allows the selective extraction of target substances from multicomponent solutions. Inorganic anion exchangers arrived in the water business relatively recently to achieve the newly approved standards for arsenic levels in drinking water. LDHs (or hydrotalcites, HTs) are theoretically the best anion exchangers due to their potential to host anions in their interlayer space, which increases their anion removal capacity considerably. This potential of the interlayer space to host additional amounts of target aqueous anions makes the LDHs superior to bulk anion exchanger. The other unique advantage of these layered materials is the flexibility of the chemical composition of the metal oxide-based layers and the interlayer anions. However, until now, this group of “classical” anion exchangers has not found its industrial application in adsorption and catalysis at the industrial scale. To accelerate application of LDHs in water treatment on the industrial scale, the authors critically reviewed recent scientific and technological knowledge on the properties and adsorptive removal of LDHs from water on the fundamental science level. This also includes review of the research tools useful to reveal the adsorption mechanism and the material properties beyond the nanoscale. Further, these properties are considered in association with the synthetic methods by which the LDHs were produced. Special attention is paid to the LDH properties that are particularly relevant to water treatment, such as exchangeability ease of the interlayer anions and the LDH stability at the solid-water interface. Notably, the LDH properties (e.g., rich speciation, hydration, and the exchangeability ease of the interlayer anions with aqueous anions) are considered in the synthetic strategy context applied to the material preparation. One such promising synthetic method has been developed by the authors who supported their opinions by the unpublished data in addition to reviewing the literature. The reviewing approach allowed for establishing regularities between the parameters: the LDH synthetic method―structure/surface/interlayer―removal―suitability for water treatment . Specifically, this approach allowed for a conclusion about either the unsuitability or promising potential of some synthetic methods (or the removal approaches) used for the preparation of LDHs for water purification at larger scales. The overall reviewing approach undertaken by the authors in this work mainly complements the other reviews on LDHs (published over the past seven to eight years) and for the first time compares the properties of these materials beyond the nanoscale. [ABSTRACT FROM AUTHOR]

The goal of the study was to check the possible use of halloysite (Hal) nanotubes as a controlled release natural antioxidant device with quercetin as the active component. The mineral was thoroughly characterized by various techniques including the determination of particle and tube morphology, specific surface area, pore size and volume, and surface energy. The high surface energy of Hal predicted strong adsorption of active molecules on its surface and consequently difficult release. FTIR spectroscopy confirmed the existence of strong interactions, energetically heterogeneous Hal surface and multilayer coverage at large loadings. FTIR and XRD experiments proved the complete lack of intercalation and showed that below 3.5 wt% quercetin loading, most of the molecules are located within the Hal tubes. Molecular modeling indicated the parallel orientation of quercetin molecules with the surface. Critical concentrations derived from various measurements agreed well with each other further confirming that up to about 4.0 wt% loading, quercetin is bonded very strongly to the Hal surface. As a consequence, the dissolution of active molecules is very difficult or impossible, especially into apolar media; thus, neither stabilization nor controlled release effect can be expected below that concentration. [ABSTRACT FROM AUTHOR]

The effects of multiwall carbon nanotube (CNT) inclusions on the crystalline structure of poly(vinylidene fluoride) (PVDF), and on the dielectric properties of PVDF/CNT nanocomposites (NCs), prepared by melt mixing, were investigated by employing X-ray diffraction, differential scanning calorimetry, and dielectric spectroscopy techniques. Our results imply that, in the NCs, the formation of β-phase crystals depends on specific compression treatment in the melt and fast cooling. Dielectric measurements on NCs, with CNT concentrations below the electrical percolation threshold, reveal that the dielectric strength of the two relaxation processes in the amorphous phase and dielectric permittivity, ϵ′, measured within the broad temperature range from −150 °C to 60 °C, increase strongly with increasing CNT concentration. This enhancement of amorphous PVDF polarizability has been attributed to the increase of the local electric field, due to local polarization generated at the surface of conductive inclusions/CNT clusters. [ABSTRACT FROM AUTHOR]

The elastomeric composites using styrene butadiene rubber (SBR) as the polymeric matrix with two types of carbon nanofillers, carbon black and carbon nanotubes, are prepared by melt mixing with the aim to use them as sensors of organic gases for monitoring industrial environments. The prepared composites contain various amounts of conducting nanofillers and are cross-linked before examination for gas sensing. The electrical conductivity of the prepared composites is measured and the percolation threshold is calculated for both types of composites. The first aim is to determine compositions slightly above the percolation threshold for later testing of the sensing properties. Swelling/deswelling experiments have also been performed. The dispersion of conducting fillers in SBR matrix is studied by scanning and transmission electron microscopy techniques, and the mechanical properties of the pure matrix and all prepared composites are determined by tensile testing. Three organic gases, toluene, tetrahydrofuran, and n-hexane, in various mixtures with air are used to examine the ability of the prepared composites to react in their presence by changing the electrical properties. Cyclability of the sensing performance of the composites is also examined. Sensing results reveal the suitability of the prepared SBR-based materials as sensors for harmful solvents and gases widely used in industry. [ABSTRACT FROM AUTHOR]

The aqueous phase hydrogenation of furfural to cyclopentanone was investigated using carbon supported Pd–Cu catalysts prepared by various methods. The most active and selective Pd–Cu catalysts were obtained using electroless plating procedure of deposition of copper in the presence of tartrate carboxylate ligands. It is an alternative and promising way to deposit metal nanoparticles onto the surfaces of porous solid supports. As the XRD data revealed in these catalysts beside metallic palladium with the particle sizes 6.8 nm the copper exist mainly in Cu + oxidation state as Cu 2 O and the metallic copper is practically absent. The selectivity to cyclopentanone was enhanced gradually by the addition of 3, 5 and 10 wt% of copper precursor on the pre-reduced 5%Pd/C catalyst. An appropriate Pd 0 and Cu + distribution is presumed to be a key in gaining excellent catalytic activity. Under reaction conditions where mass-transfer effects were eliminated the furfural conversion about 98% and cyclopentanone yield 92.1 mol% were achieved using only 1 wt% concentration of 5%Pd–10%Cu/C catalyst and reaction time 1 h. According to the proposed mechanism the dominant parameters responsible for reaching very high selectivity of cyclopentanone are (i) very high yield of primary formed furfuryl alcohol and (ii) higher rate of its subsequent conversion to cyclopentanone via the pathway not involving 4-hydroxy-2-cyclopentenone as the main intermediate. [ABSTRACT FROM AUTHOR]

Polypyrrole-coated multi-walled carbon nanotubes (PPy/MWCNT) were synthesized using a three-step chemical oxidative polymerization and were simply deposited by an ex situ method from n -butyl alcohol dispersions onto conducting FTO glasses to be used as a low-cost replacement for Pt counter electrodes (CE) in dye-sensitized solar cells (DSSCs). PPy/MWCNT CEs, compared to PPy CEs, have significantly higher interlayer cohesion and adhesion to the FTO substrate, which increases with the MWCNT ratio. The network structure of PPy/MWCNT CEs, with a larger surface area compared to PPy CEs (characterized by SEM), has a positive effect on the charge transfer resistance ( R ct ), and the PPy/MWCNT CE sample with a ratio of 70:30 reaches a lower R ct than the standard Pt CE, as measured by electrochemical impedance spectroscopy. PPy/MWCNT CEs have reasonable catalytic activities and good stability in the presence of an iodide/triiodide electrolyte, as measured by cyclic voltammetry. The conversion efficiency of the DSSC with PPy/MWCNT (70:30) CEs reaches a ∼10× higher value ( η = 4.9%) than the DSSC with pristine PPy CEs ( η = 0.5%) and a ∼30% lower value than the standard DSSC with Pt CEs ( η = 7.1%). [ABSTRACT FROM AUTHOR]

A series of compounds KTaF6, K2TaF7 and K3TaF8 and KNbF6, K2NbF7 and K3NbF8 was investigated by means of XPS and MAS NMR spectroscopy and DSC measurements. Electron binding energies of all accessible orbitals were discussed and, for the first time, correlations between different orbital energies were examined. 19F MAS NMR data and other NMR parameters of the investigated compounds were correlated with structural information, as well as with XPS data. Also a complete set of DSC data was presented including a number of phase transitions and their heat contents. Based on measured characteristics it was shown how differences in the electronic structure of isostructural compounds influence the spectral and thermo-chemical behaviour of the investigated pairs, i.e. KTaF6vs. KNbF6, K2TaF7vs. K2NbF7 and K3TaF8vs. K3NbF8. It was concluded that the differences in K 2s orbital energies play an important role in the different behaviour of tantalate and niobate analogues. [ABSTRACT FROM AUTHOR]

Low-temperature plasma was used to improve the surface and adhesive properties of wood. The pre-treatment of wood surfaces using radio-frequency (RF) discharge plasma is attractive for various wood applications, mainly because of the high efficiency and low production cost of the process. In addition, a significant increase in the polar component of the wood surface energy, which is associated with the presence of acid–base interactions (electron donor–acceptor bonds), after modification by RF discharge plasma was identified. The treatment of wood by RF plasma exhibited an aging effect, with the modified surface never recovering its initial hydrophobic state. Indeed, the enhancement of the wettability of wood is necessary for promoting better adhesion with water-based adhesives and coatings, which is currently the subject of ongoing study. [ABSTRACT FROM AUTHOR]

The atmospheric pressure ambient air and oxygen plasma treatment of flat aluminum sheets using the so-called Diffuse Coplanar Surface Barrier Discharge (DCSBD) were investigated. The main objective of this study is to show the possibility of using DCSBD plasma source to activate and clean aluminum surface. Surface free energy measurements, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDX) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) were used for the characterization of the aluminum surface chemistry and changes induced by plasma treatment. Short plasma exposure times (several seconds) led to a significant increase in the surface free energy due to changes of its polar components. Various ageing effects, depending on the storage conditions were observed and discussed. Effects of air and oxygen plasmas on the removal of varying degrees of artificial hydrocarbon contamination of aluminum surfaces were investigated by the means of EDX, ATR-FTIR and XPS methods. A significant decrease in the carbon surface content after the plasma treatment indicates a strong plasma cleaning effect, which together with high energy efficiency of the DCSBD plasma source points to potential benefits of DCSBD application in processing of the flat aluminum surfaces. [ABSTRACT FROM AUTHOR]