Addition polymerization of three norbornene-type monomers derived from various diamines and cis-5-norbornene-exo-2,3-dicarboxylic acid anhydride in the presence of Pd complexes with an N-heterocyclic carbene ligand was studied. The polymerization conditions for these bifunctional polymers containing imide fragments were optimized, which made it possible to produce the target polymers in yields of up to 75

NiO–In2O3 composites were synthesized by the impregnation of indium oxide nanoparticles with nickel nitrate salt. The phase composition and microstructure, as well as the conductivity of composites over a wide temperature range, have been studied. The introduction of nickel oxide into the In2O3 leads to an increase in its resistance. The time distributions of the annihilation radiation of positrons have been studied in the obtained composites. The results are consistent with the data of studies of free volume in samples by low-temperature nitrogen sorption. The possibility of observing point-charged defects or their clusters in metal oxide composites by the positron method is demonstrated. A correlation is observed between changes in the resistance of impregnated indium oxide samples and the intensity of the positron component associated with annihilation in point-charged defects.

A new high-temperature allothermal gasification technology is used to process three types of oil waste: ground oil sludge (GOS), tank oil sludge (TOS), and petcoke. The gasifying agent (GA), mainly composed of H2O and CO2 at a temperature above 2300 K and atmospheric pressure, is produced by pulsed detonations of a near-stochiometric methane-oxygen mixture. The gasification experiments show that the dry off-gas contains 80–90 vol.% combustible gas composed of 40–45 vol.% CO, 28–33 vol.% H2, 5–10 vol.% CH4, and 4–7 vol.% noncondensable C2–C3 hydrocarbons. The gasification process is accompanied by the removal of mass from a flow gasifier in the form of fine solid ash particles with a size of about 1 μm. The ash particles have a mesoporous structure with a specific surface area ranging from 3.3 to 15.2 m2/g and pore sizes ranging from 3 to 50 nm. The measured wall temperatures of the gasifier are in reasonable agreement with the calculated value of the thermodynamic equilibrium temperature of the off-gas. The measured CO content in the off-gas is in good agreement with the thermodynamic calculations. The reduced H2 content and elevated contents of CH4, CO2, and CxHy are apparently associated with the nonuniform distribution of the waste/GA mass ratio in the gasifier. To increase the H2 yield, it is necessary to improve the mixing of waste with the GA. It is proposed to mix crushed petcoke with oil sludge to form a paste and feed the combined waste into the gasifier using a specially designed feeder.

The development of polymers with high separation characteristics for the efficient removal of carbon dioxide from bio-/natural gases is the key to reducing the environmental impact of CO2. In this work, preparation and gas-separation properties of novel vinyl-addition polynorbornenes containing oxirane-moieties at spiro centers, which combine high CO2-permeability with remarkable selectivities for separation of CO2 from its mixtures with nitrogen and methane are published. Gas permeability data of the epoxidized polymer based on 5-ethylidene-2-norbornene exceed the Robeson upper bound of 2019 for the CO2/N-2 system (CO2 permeability is 1000 Barrer, alpha(CO2/N-2) = 67)). Separation experiments with mixtures of gases confirm the high separation performance of this polymer. In particular, the data for CO2/CH4 separation are above or close to the upper bound of 2018 for mixed gases. A similar effect of introducing oxirane moieties into spiro centers is also shown for another vinyl-addition polymer derived from 5-isopropylidene-2-norbornene and is not observed for a related polymer bearing oxirane moieties at the ends of side chains. A simple synthesis of the epoxidized polymer from available 5-ethylidene-2-norbornene, combined with high CO2-permeability and selectivities, may open a window for industrial applications of this polymer in important membrane processes, in particular, for natural/biogas upgrading.

Spiro-Epoxy Moieties Vinyl-addition polynorbornenes with spiro epoxy moieties show exceptional separation characteristics for industrial important pairs of gases, namely, CO2/CH4 and CO2/N2. In article number 2405461, Maxim V. Bermeshev and co-workers show that the discovered effect of spiro epoxy moieties on CO2 separation performance can become a new powerful tool for the targeted development of polymers, possessing enhanced permeability of CO2 and CO2/gas selectivities.

Data on microporosity (micropore size distribution) in the range from several angstroms to several nanometers, obtained by measuring the positron annihilation lifetime (PALS method) and by measuring CO 2 sorption (low-temperature gas sorption, LTGS) are collated for a number of polymers with amorphous (polyetherimides, PEI) and semicrystalline (polyphenylene oxides, PPO) structures. The microporosity estimates based on the positron annihilation and CO 2 sorption data are compared with published data obtained both experimentally and by the group contribution method for the permeability of these materials. The discrepancies found and their possible causes are discussed.

The paper presents the results of experimental studies on the production of fine char powder from sunflower seed husks by a novel method of thermomechanical treatment with pulsed shock waves and supersonic jets of the mixture of ultra-superheated (above 2000 °C) steam and carbon dioxide, as well as the results of examination of the produced char powder in terms of its chemical, phase, and granulometric composition and structural, morphological, and texture characteristics. The objective of the research is to explore the possibility of using the resulting char powder as a sorption-active material for organic substances. It is shown that the obtained char particles and their agglomerates have an average size of 20–30 nm and 12–24 µm, respectively, have the shape of disks and ellipsoids, consist mainly of amorphous carbon (up to 56 wt%) and oxygen (up to 42 wt%), and have a specific surface area of 1.1–1.7 m2/g. It is concluded that such a char powder can be used as an absorbent for organic substances when dried and deagglomerated.

Poly(2,6-dimethylphenylene oxide-1,4) (PPO) belongs to a fairly investigated group of polymers that, nevertheless, provokes permanent research interest. The current study is focused on a combination of various physicochemical methods of polymer testing (DSC; molecular weight distribution; surface area by low-temperature adsorption isotherms of nitrogen and carbon dioxide; X-Ray diffraction analysis; hydrostatic measurement of density; gas permeability and diffusion measurement) with variation of molecular weight and different states of polymer samples (amorphous, semi-crystalline, biaxial-oriented). The alteration of the density, gas permeability and diffusion parameters is evaluated through modeling of PPO as a polymer-polymer blend material with amorphous, nano-sized crystalline (<= 7 nm), and so-called rigid amorphous fraction (RAF) phases. The estimation of the phase properties of PPO samples allows to conclude that the permeability and diffusion characteristics decline in a row crystalline > amorphous > RAF.

Based on positron annihilation and low-temperature gas (CO2) sorption data, we discuss the nature of size distribution of micropores in a number of polynorbornenes with various substituent groups in the side chain. The local stiffness of highly permeable glassy polymers suggests that they are microheterogeneous. In this case, distributions that are bimodal in nature seem quite possible, although unimodal cases cannot be excluded either. The positron annihilation data are consistent with these concepts and correlate with permeability. At the same time, the positron and sorption data on porosity are found to have discrepancies, which are explained either by limited mobility of the positronium atom or by inaccuracy of description of the sorption curve according to the density functional theory (NLDFT) and the Monte Carlo method (GCMC).

The nature of micropore size distribution in a number of amorphous polymer glasses (membrane materials and sorbents) has been discussed on the basis of data on positron annihilation lifetime spectroscopy (PALS) and low-temperature CO 2 gas sorption (LTGS). The LTGS (CO 2 ) technique in combination with mathematical processing by the density functional theory gives a multimodal size distribution of micropores in the range of effective diameters of 0.5–1.5 nm for PIM-1 type polymers of intrinsic microporosity. The positron annihilation data (time distribution of annihilation emission events) are also satisfactorily processed under the assumption of multimodality. The results have been discussed in terms of the “local rigidity” of the materials under consideration.

ABSTRACTHerein the stereoselective two‐step synthesis of pure exo‐5‐trimethylsilylnorbornene is reported. The monomer proved to be highly reactive in both metathesis and addition polymerization. ROMP polymerization was catalyzed by the first‐generation Grubbs catalyst. High‐molecular‐weight saturated addition polymers were prepared using nickel or palladium complexes as precatalysts and Na+[B(3,5‐(CF3)2C6H3)4]− and/or MAO as cocatalysts. The obtained addition polynorbornenes are highly gas permeable and microporous materials possessing large free volume and BET surface area (up to 540 m2/g). The influence of the substituent orientation (exo‐ vs. exo‐/endo‐mixture) on polymer properties was established. The metathesis polymer based on exo‐isomer exhibits 1.5‐ to 2‐fold increase of permeability coefficients for all gases in comparison to the similar polymer based on the mixture of exo‐ and endo‐isomers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1234–1248

Based on the experimental data obtained by the authors in a number of previous studies, the limits of applicability of positron annihilation lifetime spectroscopy (PALS) and low-temperature gas sorption (LTGS) to determination of nanoporosity (size distribution of nanopores in the range from a few fractions of a nanometer to 50 nm) in polymeric membrane materials and sorbents are discussed. It turns out that none of these methods is universal. The possibility of using each of them is determined by different factors, with the cases considered being finely divided polymer materials and the membranes per se cast from powders. It has been shown that the particle size factor is important for the applicability of LTGS. The possibility of using PALS depends on the concentration of nanopores of a given size.

The limits of application of positron annihilation lifetime spectroscopy and low temperature gas sorption for studying nanoporosity of polymer sorbents and membrane materials are discussed relying on the results previously obtained by the authors.For the two methods, limitations are determined by different factors: the dispersion of the material is essential for low temperature gas sorption, while concentration of nanopores of given size is important for positron annihilation lifetime spectroscopy.The both methods came out to be a useful addition to each other in the studies of micropores and mesopores.

New series of 4,4'-bis(pentafluorophenyl)- and 4,4'-bis(nonafluoropheny1)-containing monomers based on hexafluorobenzene or decafluorobiphenyl as well as on para- and meta-connecting dihydroxylsubstituted compounds or tetrafluorobenzene- and 1,1,1,3,3,3-hexafluoropropane-based dihydroxylsubstituted compounds were synthesised. Fluorinated poly(arylene ether)s having perfluorinated aromatic units as well as both rigid dibenzodioxin and spirobisindane fragments were successfully obtained by interaction of the synthesized core-fluorinated monomers with 5,5',6,6'-tetrahydroxy3,3,3',3'-tetramethy1-1,1'-spirobisindane. The chemical structures of the prepared monomers and polymers were determined using H-1, C-15, F-19 NMR and FTIR spectroscopy techniques. All the obtained polymers were completely soluble in chloroform, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide. Polymers derived from 4,4'-bis(nonafluorophenyl)-containing monomers have higher average molecular masses (M-w) in the range 47,000-88,300 and are able to form robust, solvent-cast films. Good thermal stabilities in air (up to 350 degrees C) were observed in all fluorinated polymers. The Brunauer-Emmett-Teller specific surface area and the pore size of polymers can be controlled by varying the type of the initial fluorinated monomers. It was shown that introduction of perfluorobiphenyl units is an effective tool for increasing the surface area up to 156.8 m(2) g(-1). (C) 2017 Elsevier B.V. All rights reserved.