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We explored two approaches to recover uranium and plutonium from aqueous solutions at pH 4 and pH 7 using water-soluble star-like polyacrylamide polymers with a dextran core. In the first approach, a solution comprising a neutral or ionomer polymer was mixed with a radionuclide solution to form polymer–metal complexes that were then retained by ultrafiltration (UF) membranes under applied pressure. The same polymers were first deposited on the membrane in the second approach using pressure-driven flow. The applied polymers had an overall diameter of gyration of 120 nm, which exceeded the nominal diameter of the UF membrane pores. The polymers showed a high affinity to uranyl but could also be used to extract Pu from neutral or near-neutral pH solutions. Direct-flow single-step filtration and alpha spectrometry demonstrated that the UF membranes containing star-like copolymers could recover 99% of U and up to 60% of Pu from deionized water after filtering 15 mL solutions containing 25 ppm and 33 ppb of the actinides, correspondingly. The sorption capacity of the polymers for uranium could be measured as 1mg U per mg of the polymer after six subsequent filtration steps. Alpha spectroscopy of the deposited actinides revealed peculiarities of the structural organization of polymers and their complexes with U or Pu, depending on the approach. Though both approaches were efficient, the second approach (deposition of the polymer on the membrane followed by filtration) has an additional advantage of protecting the membrane pores from capillary collapse by filling them with the polymer chains. Therefore, these polymer-modified membranes could be used either in continuous or multi-step filtration process with drying after each step without deterioration of their sorption characteristics. [ABSTRACT FROM AUTHOR]

Plastic scintillators (PS) allow design of portative lightweight devices for quantification of low‐activity radiation sources. We have recently suggested a new type of organic fluorophores based on triphenyl pyrazoline (PZ) derivatives with high fluorescence quantum yield showing high radioluminescence when combined with a polyvinyltoluene (PVT) matrix. In this publication we report on radioluminescence properties of the PZ−X family with various halogen substitution (X=F, Cl, Br, I), or having vinyl functional group (vPZ, X=vinyl). PS based on such fluorophores and PVT matrix can be prepared as bulk samples, micrometer size beads or cladding on optical fibers. Application of fluorophores with vinyl functional groups enabled their enhanced interaction with the matrix due to covalent bonding between the components. We demonstrate high performance of PZ−X fluorophores and especially vPZ fluorophore in fabrication of nanocomposites for detection of various types of radiation. Scintillators have enhanced gamma ray detection capabilities with an addition of triphenyl Bi, or Gd2O3 nanoparticles. High fluorescence quantum yield and luminosity of PZ fluorophores allows dramatical reduction of their content in PS systems. Mechanisms of energy transfer and conversion during scintillation process are discussed. Special consideration is given to enhancement of α/β and neutron/gamma (n/γ) pulse shape discrimination (PSD) function of the developed scintillators. [ABSTRACT FROM AUTHOR]

Abstract: Combining extraction and scintillation properties within the same material is a relatively new approach in development of sensors for detection of radioactive elements. Structural organization of such materials at a nanoscale typically offers higher efficiency of detection and shorter response time. In this contribution, several new protocols are discussed for fabrication of stable extractive scintillating systems based on commercial Superlig 620 (SL) material with high affinity to radiostrontium. Application of hybrid organic–inorganic beads with SL particles used as core and halloysite clay nanotubes (HNT) modified with a polyvinyltoluene (PVT) brush as a permeable shell combines high‐performance extracting properties of the SL material with efficient light emission properties of the polymer scintillator. The developed SL–HNT–PVT hybrid extractive scintillating material allows real‐time detection of low‐level concentrations of radiostrontium in water. Moreover, the suggested approach is not limited to detection of Sr but can find broader application in development of chemical, biological, or radioluminescent sensors and multifunctional materials. [ABSTRACT FROM AUTHOR]

Optical and photovoltaic properties were studied for ternary photovoltaic cells containing a traditional donor-acceptor bulk-heterojunction (BHJ) active layer modified with polymethine dye molecules in a broad range of compositions and wavelengths. An effect of composition induced optical transparency, due to the strong modification of the density of states, was observed for symmetrical compositions with approximately equal amount of components. Based on our spectroscopic ellipsometry and atomic force microscopy (AFM) studies we can suggest that the variation of the refractive index, which is significantly reduced in the visible range for ternary systems, is involved in the physical mechanism of the phenomenon. Despite of an addition of the IR absorbing component (which allows broadening of the absorption band to up to 800 nm) no improvement in the power conversion efficiency (PCE) is observed in comparison to the binary BHJ system (P3HT:PCBM). Nevertheless, we believe that further advance of the efficiency will be possible if the energy levels will be chemically designed to avoid formation of charge traps at the BHJ interface during light excitation. Such fine adjustment of the system should become possible with a proper choice of polymer:dye composition due to a high versatility of the polymethine dyes demonstrated in previous studies. [ABSTRACT FROM AUTHOR]

Herein, we present a novel acid-less synthetic approach for in-situ polymerization of aniline synchronized with reduction of graphene oxide to graphene. This method provides uniform deposition of ordered polyaniline nanotubes over the surface of graphene nanosheets. The synthesized graphene-polyaniline nanocomposite has the ability of complete removal of harmful dyes commonly used in industry: such as methyl orange, methylene blue, and rhoadmine B from the waste water under the exposure to natural sunlight. The system can be used as an efficient solar energy operated photocatalyst due to effective suppression of recombination of the charge carriers. The unique spatial structure of the graphene-polyaniline nanocomposite has high chemical stability, can be recycled after photolysis, and allows using in multiple cycles without reduction in its photocatalytic activity. In addition, the graphene-polyaniline nanocomposite exhibits strong near-infrared (NIR) absorption, good photothermal stability, as well as shows substantial thermal energy generation under exposure to 808 or 980 nm NIR lasers. The electrical conductivity of polyaniline nanotubes is improved as a result of their conjugation with graphene nanosheets in the nanocomposite. Owing to its outstanding photocatalytic activity and chemical stability, the reported graphene-polyaniline nanocomposite has a great potential in purification of industrially generated waste water. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report on the synthesis of two new IR range merocyanine dyes. [•] Photovoltaic properties of P3HT–PCBM–dye system depend on the dye concentration. [•] New physical phenomenon of photo-induced current hysteresis is reported. [•] Observed photoresistance behavior can be connected to polar properties of the dyes. [Copyright &y& Elsevier]

Abstract: The near-surface crystallization behaviour of poly(ethylene terephthalate) films of various thickness, spin-cast from solution onto silicon substrates, has been studied. In the as-cast state, the films are amorphous, with featureless morphology. A relationship is mapped between the film thickness (in the range 3 nm–700 nm), the isothermal annealing temperature (ambient to 150 °C), and the crystalline morphology. Two distinct morphologies are observed which are associated with surface-specific crystallization and bulk crystallization (producing much rougher film surfaces). The surface crystallization process is associated with a top-surface region (measured to be of about 13 nm in depth) of lower glass transition temperature, where, at temperatures between the surface and bulk crystallization temperatures, only the material in the more-mobile surface region is able to reorganize to form crystals. This phenomenon is observed for films of all the thicknesses studied and it is therefore concluded that this is not specifically a thin-film phenomenon, rather a surface-specific phenomenon possible in material of any thickness. [Copyright &y& Elsevier]

Abstract: Submicron poly(vinylidene fluoride) (PVDF)/polyaniline (PANI) core–shell latex particles are synthesized and examined as an active component in a simple conductometric chemical sensor. The structure and physical properties of these particles and nanostructured composite PVDF–PANI polymer films built of them are characterized with transmission electron, atomic force, and helium ion microscopy techniques, differential scanning calorimetry, and conductivity measurements. The nanostructured composite films with conductivity of about 4 × 10−4 S/cm suitable for sensor applications are prepared by casting from the core–shell particles dispersions on glass substrates patterned with silver electrodes followed by annealing at 180 °C, i.e. above T m of the PVDF component. Sensor properties of these films are tested by measuring current–voltage (I–V) characteristics in response to varying concentration of NH3 or HCl vapors. The developed thin film sensor heterostructures with electrically conductive percolation network of PANI as an active component and employing the conductometric detection scheme show high sensitivity to both analytes. However, the polymer material is especially efficient for application to NH3 sensing with the detection limit as low as 100 ppb, and good reproducible recovery behavior upon repeated exposure to NH3 at ambient conditions. [Copyright &y& Elsevier]

Abstract: Present work reports on electrical properties of polyurethane elastomer/polyaniline (PU/PANI–HCl) composite films under tensile deformation. Two types of surface-modified and one type of volume-modified composite of PU and PANI–HCl were prepared. Surface modification of PU film was performed by swelling the parent film in aniline followed by its contact with the acidified oxidant solution to polymerize aniline and form PANI–HCl distributed inside surface/subsurface layer of the film. Volume-modified PU was prepared by mixing of the polymer components in a joint solution and then solution casting. Nonlinear current–voltage characteristics were observed for surface-modified samples while linear ones were typical of volume-modified samples. Deformation of the polymer composites caused partially reversible decrease of their conductivity characteristics, which could be described mathematically with a power law function of the strain with an exponent being dependable on the type of PU modification. Such behavior was interpreted in terms of deformation of a fractal percolation network formed in the system during its formation and chemical synthesis. [Copyright &y& Elsevier]

Abstract Water can become contaminated as a result of a leak from a nuclear facility, such as a waste facility, or from clandestine nuclear activity. Low-level on-line radiation monitoring is needed to detect these events in real time. A Bayesian control chart method, Shiryaev-Roberts (SR) procedure, was compared with classical methods, 3- σ and cumulative sum (CUSUM), for quantifying an accumulating signal from an extractive scintillating resin flow-cell detection system. Solutions containing 0.10–5.0 Bq/L of 99Tc, as T 99 cO 4 − were pumped through a flow cell packed with extractive scintillating resin used in conjunction with a Beta-RAM Model 5 HPLC detector. While T 99 cO 4 − accumulated on the resin, time series data were collected. Control chart methods were applied to the data using statistical algorithms developed in MATLAB. SR charts were constructed using Poisson (Poisson SR) and Gaussian (Gaussian SR) probability distributions of count data to estimate the likelihood ratio. Poisson and Gaussian SR charts required less volume of radioactive solution at a fixed concentration to exceed the control limit in most cases than 3- σ and CUSUM control charts, particularly solutions with lower activity. SR is thus the ideal control chart for low-level on-line radiation monitoring. Once the control limit was exceeded, activity concentrations were estimated from the SR control chart using the control chart slope on a semi-logarithmic plot. A linear regression fit was applied to averaged slope data for five activity concentration groupings for Poisson and Gaussian SR control charts. A correlation coefficient (R 2) of 0.77 for Poisson SR and 0.90 for Gaussian SR suggest this method will adequately estimate activity concentration for an unknown solution. Highlights • Shiryaev-Roberts (SR) procedure uses less volume than classical control charts. • Poisson SR uses least volume but could be confused as a false positive. • Gaussian SR has low false positive rate and continuous increasing trend. • Activity concentration can be estimated from SR control chart slope. [ABSTRACT FROM AUTHOR]

Abstract Polybenzoxazines belong to next-generation highly crosslinked thermostable resins with physical properties that go far beyond traditional high temperature polymer networks. Due to a unique set of properties, they have significant advantages over other existing thermosets. Commercial availability and wide structural diversity of the starting feedstock for the polybenzoxazines synthesis also are important benefits of such polymer systems that allow reducing production cost with simultaneous broadening of their useful properties. In our review, we discuss recent advancements in the field of fluorinated polybenzoxazines and their applications in the area of fuel cells, electronics, superhydrophobic and superoleophilic membranes for water purification, and some others. The review begins with consideration of general strategies for the synthesis of fluorinated polybenzoxazines. Next, we critically analyze various approaches to design of fluorinated benzoxazine-containing monomers and prepolymers, as well as the ways for incorporating fluorine atoms into their chemical structure. We highlight different pathways for fabrication of fluorinated polybenzoxazines and their composites with the emphasis on the structure-properties relationships in this remarkable polymer class. Finally, the review provides a summary of the most recent applications of polybenzoxazines and envisages future directions of research in the area of chemistry of fluorinated benzoxazines. [ABSTRACT FROM AUTHOR]

Diglycolamide ligands are widely applied in the analysis of radionuclides, especially lanthanides and actinides. They are used in liquid-liquid extraction procedures or in solid-phase extraction sorbents where they are adsorbed on the surface of hydrophobic polymers. The main objective of this study was to synthesize the N , N , N'N ′-tetrahexyl diglycolamide with one vinyl terminating group (vTHDGA) for further covalent immobilization on the polystyrene-divinylbenzene polymeric support. The obtained complexing resin (THDGA) was employed for the mechanized sample pretreatment in the Sequential Injection Analysis - Lab-on-Valve (SIA-LOV) flow system for the determination of 239Pu using ICP-MS detection. The analytical procedure was optimized in terms of selectivity towards several other radionuclides and elements forming potentially isobaric interferences in mass spectrometry. For 100 mL volume of sample to be analyzed, the method detection limit (MDL) was 96 mBq L−1 (42 pg L−1). The developed method was employed for the determination of 239Pu in real samples of a nuclear reactor coolant and spent fuel pool water from a nuclear reactor. Image 1 • Computer-controlled SIA-LOV setup with an exchangeable sorbent bed • New complexing sorbent for actinides • ICP-MS detection with examination of numerous interferences • Pu-239 determination in samples from nuclear industry [ABSTRACT FROM AUTHOR]

We studied peculiarities of the structural reconstruction within holographically recorded gratings on the surface of several different amorphous azobenzene-containing polymers. Under illumination with a light interference pattern, two processes take place in this type of polymer. The first process is the light-induced orientation of azobenzene units perpendicular to the polarization plane of the incident light. The second one is a transfer of macromolecules along the grating vector (i.e. perpendicular to the grating lines). These two processes result in the creation of a volume orientation grating (alternating regions of different direction or degree of molecular orientation) and a surface relief grating (SRG)—i.e. modulation of film thickness. One can assume that both orientation of molecules and their movement might change the local mechanical properties of the material. Therefore, formation of the SRG is expected to result also in modulation of the local stiffness of the polymer film. To reveal and investigate these stiffness changes within the grating, spin-coated polymer films were prepared and the gratings were recorded on them in two different ways: with an orthogonal circular or orthogonal linear polarization of two recording light beams. A combination of atomic force microscopy (AFM) and ultrasonic force microscopy (UFM) techniques was applied for SRG development monitoring. We demonstrate that formation of the phase gratings depends on the chemical structure of polymers being used, polymer film thickness, and recording parameters, with the height of grating structures (depth of modulation) increasing with both the exposure time and the film thickness. UFM images suggest that the slopes of the topographic peaks in the phase gratings exhibit an increased stiffness with respect to the grating depressions. [ABSTRACT FROM AUTHOR]