Synthesis and Biological Activity of Chromeno[3,2-]Pyridines.

The review summarizes all synthetic methodologies for the preparation of chromeno[3,2-]pyridines and chromeno[3,2-]quinolines. The proposed approaches are systemized based on ways for the construction of the heterocyclic system. The presence of these compounds in nature and their bioactivity are also discussed.

Application of Infrared Pyrolysis and Chemical Post-Activation in the Conversion of Polyethylene Terephthalate Waste into Porous Carbons for Water Purification.

In this study, we compared the conversion of polyethylene terephthalate (PET) into porous carbons for water purification using pyrolysis and post-activation with KOH. Pyrolysis was conducted at 400-850 °C, followed by KOH activation at 850 °C for samples pyrolyzed at 400, 650, and 850 °C. Both pyrolyzed and post-activated carbons showed high specific surface areas, up to 504.

Mechanistic Insights of Ethylene Polymerization on Phillips Chromium Catalysts.

Silica-supported chromium oxide catalysts, also named Phillips chromium catalysts (PCCs), provide more than half of the world's production of high- and medium-density polyethylenes. PCCs are usually prepared in the Cr(VI)/SiO form, which is subjected to reductive activation. It has been explicitly proven that CO reduces Cr(VI) to Cr(II) species that initiate ethylene polymerization; ethylene activates Cr(VI) sites as well, but the nature of the catalytic species is complicated by the presence of the ethylene oxidation products.

Fe-Co Alloy Nanoparticles Dispersed in Polymer-Derived Carbon Support: Effect of Initial Polymer Nature on the Size, Structure and Magnetic Properties.

Fe-Co alloy nanoparticles with different sizes, supported by carbon derived from several polymers, namely polyacrylonitrile, polyvinyl alcohol and chitosan, have been synthesized by a one-pot method involving simultaneous metal nanoparticle formation and polymer carbonization. The method involves the joint dissolution of metal salts and a polymer, followed by annealing of the resulting dried film. Detailed XRD analysis confirmed the formation of Fe-Co alloy nanoparticles in each sample, regardless of the initial polymer used.

Bifunctional MoS/AlO-Zeolite Catalysts in the Hydroprocessing of Methyl Palmitate.

A series of bifunctional catalysts, MoS/AlO (70 wt.%), zeolite (30 wt.%) (zeolite-ZSM-5, ZSM-12, and ZSM-22), and silica aluminophosphate SAPO-11, were synthesized for hydroconversion of methyl palmitate (10 wt.

Polyisobutylenes with Controlled Molecular Weight and Chain-End Structure: Synthesis and Actual Applications.

The polymerization of isobutylene allows us to obtain a wide spectrum of polyisobutylenes (PIBs) which differ in their molecular weight characteristics and the chemical structure of chain-end groups. The bulk of the PIBs manufactured worldwide are highly reactive polyisobutylenes (HRPIBs) with -C(Me)=CH end-groups and low-molecular weights ( < 5 kDa). HRPIBs are feedstocks that are in high demand in the manufacturing of additives for fuels and oils, adhesives, detergents, and other fine chemicals.

Pervaporation and Gas Separation Properties of High-Molecular Ladder-like Polyphenylsilsesquioxanes.

This paper presents the results of studies on the pervaporation properties (for benzene/hexane mixtures) and gas permeability (for He, H, N, O, CO, CH, CH, and CH) of ladder-like polyphenylsesquioxanes (L-PPSQ) with improved physical and chemical properties. These polymers were obtained by condensation of -tetraphenylcyclotetrasiloxanetetraol in ammonia medium. The structure of L-PPSQ was fully confirmed by a combination of physicochemical analysis methods: H, Si NMR, IR spectroscopy, HPLC, powder XRD, and viscometry in solution.

Dispersant and Protective Roles of Amphiphilic Poly(ethylene phosphate) Block Copolymers in Polyester/Bone Mineral Composites.

Composites of synthetic bone mineral substitutes (BMS) and biodegradable polyesters are of particular interest for bone surgery and orthopedics. Manufacturing of composite scaffolds commonly uses mixing of the BMS with polymer melts. Melt processing requires a high homogeneity of the mixing, and is complicated by BMS-promoted thermal degradation of polymers.

Stability of Porous Polymeric Membranes in Amine Solvents for Membrane Contactor Applications.

Membrane gas-liquid contactors have great potential to meet the challenges of amine CO capture. In this case, the most effective approach is the use of composite membranes. However, to obtain these, it is necessary to take into account the chemical and morphological resistance of membrane supports to long-term exposure to amine absorbents and their oxidative degradation products.

Effect of Molecular Weight and Chemical Structure of Terminal Groups on the Properties of Porous Hollow Fiber Polysulfone Membranes.

For the first time, polysulfones (PSFs) were synthesized with chlorine and hydroxyl terminal groups and studied for the task of producing porous hollow fiber membranes. The synthesis was carried out in dimethylacetamide (DMAc) at various excesses of 2,2-bis(4-hydroxyphenyl)propane (Bisphenol A) and 4,4'-dichlorodiphenylsulfone, as well as at an equimolar ratio of monomers in various aprotic solvents. The synthesized polymers were studied by nuclear magnetic resonance (NMR), differential scanning calorimetry, gel permeation chromatography (GPC), and the coagulation values of 2 wt.

Controlled Polymerization.

An amazing variety of polymerization mechanisms enables the creation of polymers with given microstructures and comonomer sequences [...

Conversion of polyethylene terephthalate waste into high-yield porous carbon adsorbent via pyrolysis of dipotassium terephthalate.

A method for conversion of polyethylene terephthalate (PET) waste into porous carbon material is proposed. The recycling of PET bottle waste includes the stages of low-temperature hydrolysis of the polymer and subsequent pyrolysis at 800 °C. To provide PET hydrolysis at ∼150 °C and atmospheric pressure, the polymer was pre-dissolved in dimethyl sulfoxide and then an aqueous solution of potassium hydroxide was added.

Eco-Friendly OSN Membranes Based on Alginate Salts with Variable Nanofiltration Properties.

In this work, membranes for organic solvents nanofiltration (OSN) based on a natural polymer, sodium alginate, were fabricated. They are chemically stable in organic solvents, including aprotic polar solvents. The unique advantage of these membranes is the absence of toxic reagents and solvents during their production.

Reclaiming of Amine CO Solvent Using Extraction of Heat Stable Salts in Liquid-Liquid Membrane Contactor.

Amine CO solvents undergo oxidative degradation with the formation of heat stable salts (HSS). These HSS reduce the sorption capacity of amines and lead to intense corrosion of the equipment. In our work, we propose a membrane-supported liquid-liquid extraction of the HSS from alkanolamines.

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P-OH Fragments: Part 2-Sidechain Phosphorus-Containing Polyacids.

Macromolecules containing acidic fragments in side-groups—polyacids—occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. The chemical nature of the phosphorus results in the diversity of acidic >P(O)OH fragments in sidechain phosphorus-containing polyacids (PCPAs) that can be derivatives of phosphoric or phosphinic acids.

Ratiometric i-Motif-Based Sensor for Precise Long-Term Monitoring of pH Micro Alterations in the Nucleoplasm and Interchromatin Granules.

DNA-intercalated motifs (iMs) are facile scaffolds for the design of various pH-responsive nanomachines, including biocompatible pH sensors. First, DNA pH sensors relied on complex intermolecular scaffolds. Here, we used a simple unimolecular dual-labeled iM scaffold and minimized it by replacing the redundant loop nucleosides with abasic or alkyl linkers.

Spinning of Polysulfone Hollow Fiber Membranes Using Constant Dope Solution Composition: Viscosity Control via Temperature.

The dope solution viscosity is an important parameter that largely determines the properties of hollow fiber membranes. In the literature available today, the change in viscosity is carried out only by changing the quantitative and/or qualitative dope solution compositions. However, such an important spinning parameter as temperature should significantly affect the dope solution viscosity.

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P-OH Fragments: Part 1. Polyphosphodiesters.

Among natural and synthetic polymers, main-chain phosphorus-containing polyacids (PCPAs) (polyphosphodiesters), stand in a unique position at the intersection of chemistry, physics, biology and medicine. The structural similarity of polyphosphodiesters PCPAs to natural nucleic and teichoic acids, their biocompatibility, mimicking to biomolecules providing the 'stealth effect', high bone mineral affinity of polyphosphodiesters resulting in biomineralization at physiological conditions, and adjustable hydrolytic stability of polyphosphodiesters are the basis for various biomedical, industrial and household applications of this type of polymers. In the present review, we discuss the synthesis, properties and actual applications of polyphosphodiesters.

Membranes Based on PTMSP/PVTMS Blends for Membrane Contactor Applications.

In this work, perspective polymeric materials were developed for membrane contactor applications, e.g., for the dissolved oxygen removal from amine CO capture solvents.

Effect of Acetone as Co-Solvent on Fabrication of Polyacrylonitrile Ultrafiltration Membranes by Non-Solvent Induced Phase Separation.

For the first time, the presence of acetone in the casting solutions of polyacrylonitrile (PAN) in dimethylsulfoxide or N-methyl-2-pyrrolidone was studied with regards to thermodynamical aspects of phase separation of polymeric solutions induced by contact with non-solvent (water), formation and performance of porous membranes of ultrafiltration range. The positions of the liquid equilibrium binodals on the phase diagrams of these three-component and pseudo-three-component mixtures were determined. For PAN-N-methyl-2-pyrrolidone-water glass transition curve on a ternary phase diagram was plotted experimentally for the first time.

Effect of Composition and Viscosity of Spinning Solution on Ultrafiltration Properties of Polyphenylene Sulfone Hollow-Fiber Membranes.

In this work, PPSUs with different molecular weights were synthesized for the development of highly permeable ultrafiltration hollow fiber membranes for the first time. The M of the synthesized polymers was controlled by varying the monomers molar ratio within 1:1-1.15 under the same synthesis conditions.

Alginate Ag for Composite Hollow Fiber Membrane: Formation and Ethylene/Ethane Gas Mixture Separation.

Membranes based on natural polymers, in particular alginate, are of great interest for various separation tasks. In particular, the possibility of introducing silver ions during the crosslinking of sodium alginate makes it possible to obtain a membrane with an active olefin transporter. In this work, the creation of a hollow fiber composite membrane with a selective layer of silver alginate is proposed for the first time.

Chain-End Functionalization of Poly(ε-caprolactone) for Chemical Binding with Gelatin: Binary Electrospun Scaffolds with Improved Physico-Mechanical Characteristics and Cell Adhesive Properties.

Composite biocompatible scaffolds, obtained using the electrospinning (ES) technique, are highly promising for biomedical application thanks to their high surface area, porosity, adjustable fiber diameter, and permeability. However, the combination of synthetic biodegradable (such as poly(ε-caprolactone) PCL) and natural (such as gelatin Gt) polymers is complicated by the problem of low compatibility of the components. Previously, this problem was solved by PCL grafting and/or Gt cross-linking after ES molding.

High Efficiency Membranes Based on PTMSP and Hyper-Crosslinked Polystyrene for Toxic Volatile Compounds Removal from Wastewater.

For the first time, membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with 5-50 wt% loading of hyper-crosslinked polystyrene sorbent particles (HCPS) were obtained; the membranes were investigated for the problem of effective removal of volatile organic compounds from aqueous solutions using vacuum pervaporation. The industrial HCPS sorbent Purolite Macronet™ MN200 was chosen due to its high sorption capacity for organic solvents. It has been found that the membranes are asymmetric when HCPS content is higher than 30 wt%; scanning electron microscopy of the cross-sections the membranes demonstrate that they have a clearly defined thin layer, consisting mainly of PTMSP, and a thick porous layer, consisting mainly of HCPS.