Gamma Irradiation and the Radiation Shielding Characteristics: For the Lead Oxide Doped the Crosslinked Polystyrene-b-Polyethyleneglycol Block Copolymers and the Polystyrene-b-Polyethyleneglycol-Boron Nitride Nanocomposites

This work aimed to research the efficiency of gamma irradiation and shielding characteristics on the lead oxide (PbO) doped the crosslinked polystyrene-b-polyethyleneglycol (PS-b-PEG) block copolymers and polystyrene-b-polyethyleneglycol-boron nitride (PS-b-PEG-BN) nanocomposites materials. The crosslinked PS-b-PEG block copolymers and PS-b-PEG-BN nanocomposites mixed with different percentage rates of PbO were used to research gamma-ray shielding characteristics. The synthesis of the copolymer was done by emulsion polymerization methods. The characterization and morphological analyses of irradiated samples were explored handling with the Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Gel Permeation Chromatography (GPC), Thermogravimetric Analysis (TGA), and Scanning Electron Microscope (SEM) methods. The gamma-rays that were emitted from the E 152u source were observed with a High Purity Germanium (HPGe) detector system and examined with a GammaVision computer program. Our samples, including the different percentage rates of the PS-b-PEG (1000, 1500, 10,000), BN, and PbO, were irradiated in various gamma-ray photon energy regions (from 121.78 keV to 1408.01 keV). Then, Linear-Mass Attenuation Coefficients (LACs-MACs), Half-Tenth Value Layer (HVL), Mean Free Path (MFP), and Radiation Protection Efficiency (RPE) values of the samples were calculated. Via crosschecking the acquired data from samples with and without PbO and BN, it was observed that, if the different percentage rates by weight nano-powder of PbO and BN are added in the polymer mixture, it can be used as a convenient shielding material against gamma rays.

INFLUENCE OF THE AROMATIC POLYMERIC MATRIX TYPE ON STABILITY OF NANOSIZED PALLADIUM CATALYSTS IN SUZUKI REACTION

Данная работа посвящена исследованию влияния типа полимерной матрицы сверхсшитого полистирола на активность и стабильность палладиевых катализаторов кросс-сочетания Сузуки. Показано, что применение сверхсшитого полистирола, функционализированного третичными аминогруппами, может быть перспективным с точки зрения обеспечения стабильности катализатора при рециклах, однако для достижения 100 % конверсии арилгалогенида (4 - броманизола) требуется применение сильного избытка фенилбороновой кислоты и основания. Катализатор на основе нефункционализированного сверхсшитого полистирола обладает более высокой активностью и позволяет, используя полуторакратный избыток фенилбороновой кислоты, достичь полной конверсии 4 - броманизола за 60 мин реакции в мягких условиях (70 °С, растворитель - смесь этанола и воды в соотношении 5:1). Недостатком такой системы является сильная адсорбция продукта кросс-сочетания в гидрофобной полимерной матрице. This work is devoted to the study of the influence of the type of polymeric matrix of hyper-crosslinked polystyrene on activity and stability of palladium catalysts of Suzuki cross-coupling. The use of the hyper-crosslinked polystyrene functionalized with tertiary amino groups was shown to be promising in terms of ensuring of the catalyst stability during recycles, but in order to achieve 100 % conversion of aryl halide (4 - bromanisole) the use of strong excess of phenylboronic acid and of a base is required. The catalyst based on non-functionalized hyper-crosslinked polystyrene had higher activity and allowed achieving complete conversion of 4 - bromanisole during the reaction under mild conditions (70 °C, ethanol and water mixture is in the ratio of 5 : 1 as a solvent) while using 1,5 - fold excess of phenylboronic acid. However, strong adsorption of the cross-coupling product in a hydrophobic polymeric matrix was found to be a disadvantage of such a system.

Solid Polymer Electrolytes Derived from Oligomeric Poly(ethylene oxide) Chain-Grafted Crosslinked Polystyrene Microspheres

A new class of lithium-ion conducting Solid Polymer Electrolytes (SPEs) has been derived from oligomeric Polyethylene Oxide (PEO)-grafted Cross-linked Polystyrene (XPS) microspheres containing one or two lithium sulfonamide moieties. The SPE containing Li:O mole ratio of 1:8 displayed excellent ionic conductivity (in excess of 10-4S/cm at 25ºC) and good electrochemical stability (4.3 volts versus Li/Li+). Thermal properties of these SPEs have also been investigated with Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). These new SPEs possess amorphous character with a glass Transition Temperature (Tg) around 135ºC, and no significant thermal decomposition until 420ºC. Synthesis and characterization including surface morphologies of these SPEs are described.

Solid Polymer Electrolytes Derived from Crosslinked Polystyrene Nanoparticles Covalently Functionalized with a Low Lattice Energy Lithium Salt Moiety

Three new crosslinked polystyrene nanoparticles covalently attached with low lattice energy lithium salt moieties were synthesized: poly(styrene lithium trifluoromethane sulphonyl imide) (PSTFSILi), poly(styrene lithium benzene sulphonyl imide) (PSPhSILi), and poly(styrene lithium sulfonyl-1,3-dithiane-1,1,3,3-tetraoxide) (PSDTTOLi). A series of solid polymer electrolytes (SPEs) were formulated by mixing these lithium salts with high molecular weight poly(ethylene oxide), poly(ethylene glycol dimethyl ether), and lithium bis(fluorosulfonyl)imide. The crosslinked nano-sized polymer salts improved film strength and decreased the glass transition temperature (Tg) of the polymer electrolyte membranes. An enhancement in both ionic conductivity and thermal stability was observed. For example, the SPE film containing PSTFSILi displayed ionic conductivity of 7.52 × 10−5 S cm−1 at room temperature and 3.0 × 10−3 S cm−1 at 70 °C, while the SPE film containing PSDTTOLi showed an even better performance of 1.54 × 10−4 S cm−1 at room temperature and 3.23 × 10−3 S cm−1 at 70 °C.

INFLUENCE OF METAL-MODIFIERS ON THE BEHAVIOR OF LIGANDLESS PALLADIUM CATALYSTS OF SUZUKI CROSS-COUPLING

В работе рассмотрены перспективы введения второго металла-модификатора в состав палладий-содержащих катализаторов кросс-сочетания Сузуки. Представлены результаты проверки каталитических свойств моно- (Pd) и биметаллических (Au-Pd, Pd-Cu, Pd-Zn) безлигандных катализаторов на основе сверхсшитого полистирола марки MN100, содержащего третичные аминогруппы, в модельной реакции кросс-сочетания 4-броманизола и фенилбороновой кислоты. Реакция проводилась на воздухе в периодическом режиме в мягких условиях (растворитель - смесь этанола и воды в объемном соотношении 4 : 1, температура 60С, основание - NaOH) в отсутствии агентов фазового переноса. Было показано, что в случае образца Pd/MN100, предварительно восстановленного в токе водорода, для достижения 100% конверсии 4-броманизола за 60 мин важно обеспечить определенный избыток фенилбороновой кислоты и NaOH (селективность по продукту кросс-сочетания при этом сохраняется равной 89%). Среди биметаллических образцов наибольшей активностью обладал катализатор Au-Pd/MN100 (достигалась 100% конверсия 4-броманизола за 15 мин реакции), однако наиболее селективным был образец Pd-Cu/MN100 (селективность составила 93%). This paper is devoted to the prospects of introducing the second metal-modifier into the composition of palladium-containing catalysts of Suzuki cross-coupling. The results of catalytic testing of mono- (Pd) and bimetallic (Au-Pd, Pd-Cu, Pd-Zn) ligandless catalysts based on hyper-crosslinked polystyrene of MN100 type containing tertiary amino-groups in the model reaction of cross-coupling of 4-bromanisole and phenylboronic acid are presented. The reaction was carried out in air in a batch mode under mild conditions (solvent - mixture of ethanol and water in a volumetric ratio of 4 : 1, temperature 60C, NaOH was used as a base) in the absence of phase-transfer agents. It was shown that in the case of Pd/MN100 sample preliminarily reduced in hydrogen flow, it is important to provide a certain excess of phenylboronic acid and NaOH in order to achieve 100% conversion of 4-bromanisole in 60 min (selectivity with respect to cross-coupling product was maintained at 89%). Among bimetallic samples, the catalyst Au-Pd/MN100 revealed the highest activity (100% conversion of 4-bromanisole was achieved in 15 min of reaction), however Pd-Cu/MN100 sample was the most selective (selectivity was 93%).

Alkali Lignin Catalytic Hydrogenolysis with Biofuel Production

In this paper synthesized palladium (Pd)-containing catalysts were used in the hydrogenolysis of lignin in the presence of a hydrogen donor solvent, i-propanol, to obtain liquid fuel components. A study of the influence of the catalyst support nature, catalyst preparation method and supercritical solvent nature on the lignin depolymerization was completed. It was found that the use of Pd-containing catalysts results in the formation of aromatic compounds (mainly benzene and toluene) for both supercritical solvents used (i-propanol and CO2). The maximum conversion of lignin (50 %) was achieved when the supercritical i-propanol was used and maximum selectivity to aromatics (over 70 %) was observed in the presence of the Pd-containing catalyst synthesized by hydrothermal deposition on the polymeric matrix of hyper-crosslinked polystyrene.