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The aim of this work was the characterization of polymer microspheres obtained by the suspension polymerization of divinylbenzene (DVB) and glycidyl methacrylate (GMA), depending on the pore-forming diluents and molar ratio of monomers. The assessed properties included the chemical and porous structure, thermal stability, and sorption capacity of the obtained polymers towards methylene blue. The abovementioned characteristic was carried out for two series of copolymers with molar ratios of monomers of 1:2, 1:1 and 2:1, synthetized with toluene and a mixture of decanol and benzyl alcohol. The structure of the polymers was confirmed by FTIR and elemental analysis. The results of TGA demonstrated the main influence on thermal stability was the composition of polymers, whereas the impact of porogens was negligible. The SBET varied in the range of 12–534 m2g−1 for polymers obtained with toluene and 0–396 m2g−1 with the mixture of alcohols. Toluene enhanced the formation of micro- and mesopores, while the mixture of alcohols enhanced the creation of meso- and macropores. For the polymers prepared with toluene, their effectiveness in water purification decreases in the following order: DVB-GMA 2:1 > DVB-GMA 1:1 > DVB-GMA 1:2, according to the decreasing values of porous structure parameters. In the case of a series obtained with a mixture of alcohols, such correlation was not observed. [ABSTRACT FROM AUTHOR]

The aim of this work was the characterization of polymer microspheres obtained by the suspension polymerization of divinylbenzene (DVB) and glycidyl methacrylate (GMA), depending on the pore-forming diluents and molar ratio of monomers. The assessed properties included the chemical and porous structure, thermal stability, and sorption capacity of the obtained polymers towards methylene blue. The abovementioned characteristic was carried out for two series of copolymers with molar ratios of monomers of 1:2, 1:1 and 2:1, synthetized with toluene and a mixture of decanol and benzyl alcohol. The structure of the polymers was confirmed by FTIR and elemental analysis. The results of TGA demonstrated the main influence on thermal stability was the composition of polymers, whereas the impact of porogens was negligible. The SBET varied in the range of 12–534 m2g−1 for polymers obtained with toluene and 0–396 m2g−1 with the mixture of alcohols. Toluene enhanced the formation of micro- and mesopores, while the mixture of alcohols enhanced the creation of meso- and macropores. For the polymers prepared with toluene, their effectiveness in water purification decreases in the following order: DVB-GMA 2:1 > DVB-GMA 1:1 > DVB-GMA 1:2, according to the decreasing values of porous structure parameters. In the case of a series obtained with a mixture of alcohols, such correlation was not observed.

Within this work, ink formulations based on polyorganosilazane (OPSZ) and divinylbenzene (DVB) were developed to be processed by inkjet printing. The formulations were studied regarding their rheological, structural, and thermal properties. The rheological results show that the new formulations meet the requirements of the inkjet printer by showing both low viscosity (below 20 mPa∙s at printing temperature) and Newtonian flow behavior even at high shear rates. Additionally, the inks have surface tensions in the range of 21 to 26 mN/m2. First, printing experiments of single layers were successfully conducted and show that the developed formulations can be processed by inkjet printing. The inks were crosslinked by UV light and then pyrolyzed at 1100 °C resulting in a ceramic yield between 75 and 42%, depending on the ink formulation. The crosslinking behavior was studied via FTIR spectroscopy, and the results reveal that crosslinking occurs mainly via free-radical polymerization of the vinyl group. Furthermore, the results indicate that silicon carbonitride (SiCN) was formed after the pyrolysis. The results of the electrical properties of the amorphous ceramics differ in dependence on the amount of DVB in the formulation. A maximum electrical conductivity of 1.2 S/cm−1 was observed for a UV-cured sample with a high amount of DVB pyrolyzed at 1100 °C. The generation in electrical conductivity is given by the formation of free carbon derived most likely by DVB. [ABSTRACT FROM AUTHOR]

The thermal decomposition product of magnesium hydroxide (MH) is magnesium oxide (MgO), which serves as the foundational material for fireproof layer construction in the condensed phase. However, the weak interaction force between particles of MgO generated by thermal decomposition leads to the insufficient strength and poor adhesion ability of the fireproof layer. The fireproof layer was easily damaged and detached in this study, resulting in the low flame-retardant efficiency of MH. In this work, polycarbosilane (PCS) and divinyl benzene (DVB) were used to modify MH, and EVA/MH/PCS/DVB composites were made via melt blending. The flame-retardant properties of EVA/MH/PCS/DVB were evaluated using the limiting oxygen index (LOI), vertical combustion (UL-94), and a cone calorimeter (CONE). The thermal stability of the composites and flame retardants was analyzed using a thermogravimetric analyzer. The char layer structure was observed and analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the LOI of the EVA/MH/PCS/DVB with 50 wt.% flame retardants in total was as high as 65.1, which increased by 160% in comparison with EVA/MH. Furthermore, the total smoke production (TSP) of the EVA/MH/PCS/DVB composite decreased by 22.7% compared to EVA/MH/PCS; the thermal stability of the MH/PCS/DVB and EVA/MH/PCS/DVB improved to some extent; and the compact residual char after the combustion of EVA/MH/PCS/DVB had fewer cracks due to the adhesive effect induced by PCS/DVB. [ABSTRACT FROM AUTHOR]

In this work, the synthesis of magnetic microspheres of poly(glycidyl methacrylate‐co‐divinylbenzene) via suspension polymerization is reported. The concentrations of divinylbenzeneand benzoyl peroxide in the microspheres synthesis are studied. The microspheres, characterized by thermal analysis , scanning electron microscopy, vibrating sample magnetometry , and light scattering detection , show good morphological control and thermal stability. This material presents a narrow size range and an appreciable fraction of superparamagnetic particles. The increase in divinylbenzene concentration can cause a decrease in the mean diameter of the microspheres. On the other hand, the increase in benzoyl peroxide concentration causes an increase in the mean diameter of the microspheres. [ABSTRACT FROM AUTHOR]

In this work, polymeric microspheres based on glycidyl methacrylate and divinylbenzene with magnetic properties are synthesized by the suspension polymerization technique. To obtain magnetic properties, magnetite particles modified by oleic acid are synthesized in the laboratory. The effects of stirring speed, concentration of magnetite added, and concentration of stabilizer on the particles' properties are studied. The magnetic microspheres are characterized according their morphology, magnetite incorporation, and magnetic and thermal properties. The incorporation of iron particles is mainly affected by stirring speed during synthesis and the amount of added magnetic material. The saturation magnetization of the microspheres is affected by the content of incorporated magnetic material. The modification with oleic acid is important for incorporation of the magnetic material in the copolymer matrix. Polymeric particles with superparamagnetic behavior are obtained with spherical morphology and saturation magnetization of 7.11 (emu g−1) when employing a monomer molar ratio of 50/50, 1% poly(vinyl alcohol), 20% magnetite particles modified by oleic acid, and stirring speed of 500 rpm. [ABSTRACT FROM AUTHOR]

Within this work, ink formulations based on polyorganosilazane (OPSZ) and divinylbenzene (DVB) were developed to be processed by inkjet printing. The formulations were studied regarding their rheological, structural, and thermal properties. The rheological results show that the new formulations meet the requirements of the inkjet printer by showing both low viscosity (below 20 mPa∙s at printing temperature) and Newtonian flow behavior even at high shear rates. Additionally, the inks have surface tensions in the range of 21 to 26 mN/m2. First, printing experiments of single layers were successfully conducted and show that the developed formulations can be processed by inkjet printing. The inks were crosslinked by UV light and then pyrolyzed at 1100 °C resulting in a ceramic yield between 75 and 42%, depending on the ink formulation. The crosslinking behavior was studied via FTIR spectroscopy, and the results reveal that crosslinking occurs mainly via free-radical polymerization of the vinyl group. Furthermore, the results indicate that silicon carbonitride (SiCN) was formed after the pyrolysis. The results of the electrical properties of the amorphous ceramics differ in dependence on the amount of DVB in the formulation. A maximum electrical conductivity of 1.2 S/cm−1 was observed for a UV-cured sample with a high amount of DVB pyrolyzed at 1100 °C. The generation in electrical conductivity is given by the formation of free carbon derived most likely by DVB.

The thermal decomposition product of magnesium hydroxide (MH) is magnesium oxide (MgO), which serves as the foundational material for fireproof layer construction in the condensed phase. However, the weak interaction force between particles of MgO generated by thermal decomposition leads to the insufficient strength and poor adhesion ability of the fireproof layer. The fireproof layer was easily damaged and detached in this study, resulting in the low flame-retardant efficiency of MH. In this work, polycarbosilane (PCS) and divinyl benzene (DVB) were used to modify MH, and EVA/MH/PCS/DVB composites were made via melt blending. The flame-retardant properties of EVA/MH/PCS/DVB were evaluated using the limiting oxygen index (LOI), vertical combustion (UL-94), and a cone calorimeter (CONE). The thermal stability of the composites and flame retardants was analyzed using a thermogravimetric analyzer. The char layer structure was observed and analyzed using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that the LOI of the EVA/MH/PCS/DVB with 50 wt.% flame retardants in total was as high as 65.1, which increased by 160% in comparison with EVA/MH. Furthermore, the total smoke production (TSP) of the EVA/MH/PCS/DVB composite decreased by 22.7% compared to EVA/MH/PCS; the thermal stability of the MH/PCS/DVB and EVA/MH/PCS/DVB improved to some extent; and the compact residual char after the combustion of EVA/MH/PCS/DVB had fewer cracks due to the adhesive effect induced by PCS/DVB.

In this study, a novel thermosensitive polymer poly(styrene co acrylonitrile co methacrylic acid co n-butylacrylate co diviniyl benzene)(SAMB) is synthesized by solvent polymerization and by copolymerization of styrene, acrylonitrile, methacrylic acid, n-butyl acrylate as a monomer, divinyl benzene as crosslinking agent and benzoyl peroxide as a initiator and poly(styrene co acryl amidoxime co methacrylic acid co n-butyl acrylate co divinyl benzene)(SAMB-Aox) is synthesized by amidoxymation of hydroxilamine hydrochloride, NH2OH·HCl. Firstly, the structure of SAMB and SAMB-Aox is characterized by FTIR, morphology of these polymers is determined by SEM and XRD, thermal properties of SAMB and SAMB-Aox also is specified by DSC and DMA and finally shape memory properties of these polymers were analyzed by bending test SAMB in 45 ℃ and SAMB-Aox at 75 ℃. The shape memory property of SAMB has a Rf value of 76% in 9 s, while the Rf value of SAMB-Aox was measured as 33.3% in 42 s. It was observed that shape recovery value decreased due to the effect of interchain hydrogen bonds after amidoxymation of the polymer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal polymerization of divinylbenzene is studied by theoretical calculations. • Each polymerization step has high selectivity for para-divinylbenzene. • The polymerization of para-divinylbenzene is more favorable thermodynamically. • The polymerization rate of para-divinylbenzene is faster than other monomers. • The fastest consumption rate of para-divinylbenzene was observed in experiments. To understand the thermal self-initiated polymerization of vinyl monomers during the divinylbenzene refining process, the differences in reaction behavior among these monomers were studied by density functional theory calculations. The calculations reveal that para-divinylbenzene (para-DVB) exhibits higher reactivity than other monomers in polymerization. Specifically, among the first step of initiation which is a Diels-Alder reaction, the reaction between para-DVB molecules shows the lowest activation energy (Ea) of 134.6 kJ/mol. Subsequently, para-DVB preferentially undergoes molecule-assisted homolysis with the products of the aforementioned Diels-Alder reaction and formatting free radicals with an Ea of 74.8 kJ/mol and a reaction rate constant (k TST) of 3.48 × 10−3 L/mol∙s. In the propagation stage, para-DVB also exhibits the highest monomer reactivity, with a k TST approximately 1.4–2.25 times greater than other monomers. The polymerization preformed under refining conditions confirms that the consumption of para-DVB is faster than that of other monomers, consistent with the DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract Shiitake mushrooms (Lentinus edodes) form a great source of protein; however, the effect of enzymatic hydrolysis to improve its flavor has not yet been investigated. To explore the effects of different protease treatments on protein degradation and flavor compounds of shiitake mushrooms, papain, neutral protease, and flavourzyme were selected for the hydrolysis of shiitake mushrooms. Proteolysis index, Trichloroacetic acid‐nitrogen soluble index, and protein content were estimated to evaluate protein degradation. Flavor amino acids and volatile components of the hydrolysate were also analyzed. Results showed flavourzyme has an advantage over the others in promoting protein degradation and improving flavor. Compared to single‐enzyme treatment, a combination treatment with three enzymes, at 1:1:1 ratio, was found to perform greater protein hydrolysis. After protease‐mediated hydrolysis, the variety and content of flavor substances (free amino acids and eight‐carbon compounds) in L. edodes increased. We concluded that protease treatment is an effective method for improving the quality and flavor of L. edodes.

In the present work, the effect of divinylbenzene (DVB) on the kinetics of post-radiation chemical graft polymerization styrene (St) on polyethylene (PE) film and its structural and morphological features were investigated. It has been found that the dependence of the degree of polystyrene (PS) grafting on the DVB concentration in the solution is extreme. An increase in the rate of graft polymerization at low concentrations of DVB in the solution is associated with a decrease in the mobility of the growing chains of PS. A decrease in the rate of graft polymerization at high concentrations of DVB is associated with a decrease in the rate of diffusion of St and iron(II) ions in the cross-linked network structure of macromolecules of graft PS. A comparative analysis of the IR transmission and multiple attenuated total internal reflection spectra of the films with graft PS shows that graft polymerization of St in the presence of DVB leads to the enrichment of the film surface layers in PS. These results have been confirmed by the data on the distribution of sulfur in these films after sulfonation. The micrographs of the surface of the grafted films show the formation of cross-linked local microphases of PS with fixed interfaces.

The specific molecularly imprinted polymer for ribavirin was fabricated by using 3‐allyloxy‐1, 2‐propanediol and acrylic acid as the functional monomers, divinylbenzene and N, N'‐methylenebisacrylamide as the cross‐linkers, and azobisisobutyronitrile as the initiator. It was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy combined with an energy dispersive X‐ray analyzer, and thermogravimetric analysis. Several factors affecting the extraction of ribavirin, such as pH, contact time, and temperature were also investigated. The molecularly imprinted polymer indicated high sorption capacity (3.1 mg g−1) for ribavirin, and the adsorption equilibrium was established after 15 min. The adsorption isotherm results could be well described with the Freundlich isotherm model. The linear range was 0.5–80 mg L−1, and recoveries ranging from 93 % to 102 % were achieved. The detection limit of ribavirin was identical at 0.82 μg L−1, and the relative standard deviation was 0.265 %. It was successfully used for ribavirin analysis in human urine and pharmaceutical samples. [ABSTRACT FROM AUTHOR]

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The blend of standard Indonesian rubber (SIR-3L) and low density of polyethylene (LDPE) with a ratio of 50/50 (w/w%) had been prepared by varying the amount of divinylbenzene (DVB) and dicumyl peroxide (DCP). The properties of SIR-3L/LDPE blends had been characterized using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and mechanical properties. The addition of divinylbenzene and dicumyl peroxide affected the properties of SIR-3L/LDPE blends. [ABSTRACT FROM AUTHOR]

Summary: Sodium‐ion batteries (SIBs) are not only cheaper to produce than lithium‐ion batteries, but the reserves of sodium in the world are also more uniform and abundant. Thus, efforts are being made to utilize sodium‐ion batteries as next‐generation large‐capacity energy‐storage devices. Sb‐based anode materials have emerged as a popular alloying material for SIB owing to their high theoretical capacity. However, Sb exhibits the problem of capacity fading owing to excessive volume expansion (approximately 390%). SiOC is a buffer material that has been investigated in terms of its ability to overcome these disadvantages; however, SiOC has the disadvantage of containing a fixed and limited free‐carbon domain. Here, high free‐carbon contained in Sb/SiOC composites (HFC‐Sb/SiOC) was easily synthesized by the heat treatment of divinylbenzene (DVB), a liquid carbon source, with silicone oil and Sb acetate. Sb nanoparticles were uniformly embedded in DVB‐modified SiOC with increased free‐carbon domains. This composite material showed cycling stability (344.5 mAh g−1 after the 150 cycles at 0.2 C) and outstanding rate properties (197.5 mAh g−1 at 5 C) as the SIB anode. The enhanced electrochemical performance is result from the increased free‐carbon domains in the SiOC matrix caused by the addition of DVB, which makes the characteristics of the SiOC material softer and more elastic, suppressing volume changes and enhancing the electrical conductivity. [ABSTRACT FROM AUTHOR]

Abstract In this research work, an Fe(III)-IIP was prepared using methacrylic acid as monomer, divinylbenzene as cross-linker, azobisisobutyronitrile as initiator. The ion imprinted polymer was functionalized with Fe(III)8-hydroxy quinolone complex under thermal conditions by copolymerization with the monomer and the cross-linker. The prepared Fe(III)-ion imprinted polymer (IIP) and non-ion imprinted polymer (Non-IIP) were characterized with fourier transform-infrared spectroscopy, scanning electron microscopic analysis and thermal gravimetric analysis. The polymer showed a good stability to thermal analysis up to a temperature of 500 °C. The size of the polymer obtained was 1 µm, large enough to be filtered easily. At pH 2.5 more affinity was observed with ion imprinted polymer in comparison to non-ion imprinted polymer. For the kinetic study, the most linear and rhythmical relation were seen in pseudo second order. The maximum sorption capacity of Fe(III) ions on Fe(III)-IIP and non-IIP was 170 and 30.0 µmolg−1, respectively. The relative selectivity factor (αr) values of Fe(III)/Fe(II), Fe(III)/Al(III) and Fe(III)/Cr(III) were 151.0, 84.6 and 91.9, respectively. The preconcentration factor was found to be 240. The developed method was successfully applied to the determination of trace Fe in the drinking water.

Comparative estimation is performed for the repeatability of results from measuring the two main parameters (peak areas and retention times) of components (carbon dioxide, sulfur compounds) of a model mixture similar in composition to natural gas. The measurements are made on a capillary column prepared for the first time with nonpolar phase poly(1-trimethylsilyl-1-propyne) (PTMSP) with dimensions of 30 m × 0.53 mm and a sorbent film thickness of 2.82 μm, and a commercial Rt–Q–BOND column 30 m long and 0.32 mm in diameter, with a nonpolar polydivinylbenzene sorbent layer 10 μm thick. The use of these columns ensures satisfactory repeatability of the chromatographic characteristics of the analyzed compounds. The relative mean standard deviation (RMSD) for retention times is no greater than 0.10%. The RMSD for the measured peak areas is less than 1.92%. A slight difference between the peak areas for sulfur dioxide and carbon disulfide (five consecutive injections) is observed on an Rt-Q-BOND capillary column. The corresponding values of the RMSD are 4.22 and 2.52%. The magnitude of the signal response of the analyzed compounds is recorded with a microcatarometer. The limits for detecting sulfur-containing compounds on the PTMSP column change from 0.40 × 10−3 to 0.82 × 10−3 mg/mL. The possibility of selectively separating the macrozone of methane and the propane–butane fraction from trace hydrocarbons, sulfur compounds that contain carbon dioxide, hydrogen sulfide, and mercaptans on a capillary column with a film thickness of 2.82 μm PTMSP is also demonstrated for the first time. [ABSTRACT FROM AUTHOR]

The present study describes the thermal properties of a series of porous microspheres synthesised from the dimethacrylate derivative of m-xylene, i.e. (4,6-dimethyl-1,3-phenylene)dimethylene bis(2-methylprop-2-enoate) and divinylbenzene via an aqueous suspension polymerisation in the presence of toluene and decan-1-ol as porogenic diluents. Various molar ratios of monomers were applied in the syntheses (1:4, 1:1, 4:1). The TG/DSC/FTIR analyses were performed in inert (helium) and oxidative (synthetic air) atmospheres. They revealed that the properties of the copolymeric microspheres were dependent on both their chemical composition and the testing atmosphere. The microspheres were stable up to 229–296 °C (in helium) and 302–308 °C (in synthetic air), as determined on the basis of the temperature of 1% mass loss. However, the most thermally stable were those synthesised at the molar ratio of the dimethacrylate derivative of m-xylene to divinylbenzene equal to 1:4. In helium, the copolymeric beads decomposed in one, two or three stages, whereas in synthetic air in two ones. The basic decomposition volatiles were carbon monoxide, carbon dioxide and organic carbonyl products, including esters, carboxylic acids and aldehydes as well as unsaturated and aromatic compounds. [ABSTRACT FROM AUTHOR]

The synergistic effect of divinylbenzene and triallyl cyanurate on the properties and structure of the thermoplastic vulcanizate prepared from a blend of polypropylene and hydrogenated styrene–butadiene–styrene triblock copolymer by vulcanization under dynamic conditions with 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane was revealed. The synergism consists in the enhancement of the strength, increase in the relative elongation, and decrease in the compression set to a greater extent then when using divinylbenzene or triallyl cyanurate separately. The synergism is caused by the increased gel fraction content and vulcanization network thickness, with preservation of the higher molecular mass of the polypropylene matrix. [ABSTRACT FROM AUTHOR]

A novel radiation grafted ETFE based proton conducting membrane was prepared by double irradiation grafting of two different monomers. The intrinsic oxidative stability of the ETFE-g-poly(styrene sulfonic acid-co-divinylbenzene) membrane was improved by reducing the gas crossover through incorporation of polymethacrylonitrile (PMAN) containing the strong polar nitrile group. A fuel cell test was carried out at 80 °C under constant current density of 500 mA cm−2 for a time exceeding 1′900 h. The incorporation of PMAN considerably improves the interfacial properties of the membrane-electrode assembly. No significant change in the membrane hydrogen crossover and performance over the testing time was observed, except for a measured decrease in the membrane ohmic resistance after 1′000 h. The combination of the double irradiation induced grafting with the use of the PMAN as gas barrier in addition to its chelating abilities (e. g. Ce3+) offers a promising strategy to develop more durable membranes for fuel cells. Image 1 • Double irradiation grafting of two different monomers was performed for the first time in literature. • Methacrylonitrile re-grafted membranes were, for the first time, prepared for PEM fuel cells. • Dimensional stability was improved by the methacrylonitrile re-grafted membranes. • The Nitrile groups enhance the gas barrier properties of the tested membranes. • Promising PEM Fuel cell durability results were obtained with the re-grafted membranes. [ABSTRACT FROM AUTHOR]

The Prins reaction and cyclopropanation of the light fraction obtained by distillation of the technical grade divinylbenzene and consisting of a mixture of 1,3- and 1,4-divinylbenzenes with admixture of 3- and 4-ethylstyrenes were studied. These reactions quantitatively give the corresponding gem-dichlorocyclopropane and 1,3-dioxane benzene derivatives. The structures of the synthesized compounds were confirmed by NMR spectroscopy and mass spectrometry. [ABSTRACT FROM AUTHOR]

Nitrogen and oxygen gas solubilities were measured in benzene, divinylbenzene, and styrene at pressures up to 3.898 MPa and at 293 K, 303 K, and 313 K, because these liquids correspond to solvent, crosslinker and monomer, respectively. Gas solubilities for an equimolar mixture of nitrogen and oxygen were measured in styrene under the same experimental conditions. Gas solubilities in the liquids for a given isotherm had a linear pressure dependence and they decreased with increasing temperature. The solubility of oxygen was about 1.8 times larger than that of nitrogen in all liquids at any given temperature. Gas solubilities of equimolar mixture (N 2 :O 2) were slightly closer to values of nitrogen than oxygen. The gas solubilities could be correlated with the forms of the Peng-Robinson equation of state to within the ARD of 1.637 and 1.310% for nitrogen and oxygen solubility by using the objective function, ∑ (x 1 , exp − x 1 , calc). The ARDs were 0.497 and 0.491% for nitrogen and oxygen solubility from Henry's law. The data and correlation allow analysis of reacting systems for the prediction of the inductive time and the oxygen or air pressure as an inhibitor in radical polymerization. Image 1 • Pure/mixed N 2 and O 2 gas solubilities were measured in benzene, styrene, divinylbenzene. • N 2 and O 2 solubilities were identical at experimental conditions studied. • Peng-Robinson equation of state was able to sufficiently correlate the solubilities. [ABSTRACT FROM AUTHOR]

Poly(4-vinylpyridine) crosslinked by 2 % divinylbenzene was partially quaternized (20 % monomer equivalents) by a bidentate Schiff base nickel complex containing C-Br function in its molecular structure using dioxane as solvent. The resulting poly(4-vinylpyridine-co-divinylbenzene)-Ni(II) Schiff base complex (PVP-co-DVB-Ni(II)-L2) was characterized using various techniques such as elemental analysis and Fourier-transform infrared (FT-IR) spectroscopy. Thermogravimetric (TG)/differential thermogravimetry (DTG) analysis of the nonmodified copolymer, free complex, and the copolymer modified with the nickel complex was carried out to elucidate the thermal behavior. The synthesized copolymer covalently grafted with the nickel(II) complex was mixed with carbon black paste to prepare a new modified electrode material. This electrode was characterized by wide-angle X-ray diffraction analysis, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and cyclic voltammetry. The electrochemical properties of the resulting modified electrode, recorded in alkaline solution, were investigated by cyclic voltammetry, revealing a well-defined redox process corresponding to the NiIII/NiII redox couple. The effects of parameters such as the scan rate and ethanol concentration were explored for electrooxidation of ethanol using this modified electrode. A mechanism for the electrooxidation of ethanol is suggested based on the cyclic voltammetry results. [ABSTRACT FROM AUTHOR]

The effect of divinylbenzene (DVB) as crosslinker on the graft polymerization of 4-vinylpyridine (4VP) from poly(ethylene-co-tetrafluoroethylene) (ETFE) films was studied. The resulted films were doped with phosphoric acid (PA) and characterized for mechanical, surface, thermal properties, and fuel cell performance. The crosslinked membrane obtained from grafting a mixture of 4VP with 1% DVB improved the polymerization kinetics and resulted in about 50% graft level depending on graft conditions. The crosslinked membranes were also found to have better mechanical properties compared to its noncrosslinked counterpart. The resulted membrane exhibited proton conductivity as high as 75 mS/cm under 50% relative humidity (RH) at 120 °C, besides almost doubling the power output of fuel cell compared to a noncrosslinked membrane. To the best of our knowledge, DVB crosslinked 4VP based ETFE membranes were, for the first time, tested in practical fuel cell test station correlating their performance to operating temperature. Furthermore, surface properties of produced membranes were additionally correlated to the degree of crosslinking. Humidity dependence is less pronounced in the produced membranes resulting in strong potential for testing at intermediate temperature (80–120 °C) polymer electrolyte membrane fuel cells. [ABSTRACT FROM AUTHOR]

In this study, a commercial polycarbosilane (PCS) and divinylbenzene (DVB) were used as the preceramic polymer precursor and crosslinking agent, respectively to form porous silicon carbide (SiC) ceramics by freeze casting DVB/camphene/PCS solutions. Porous silicon carbide (SiC) with a dendritic pore structure and connecting bridges was obtained after pyrolysis at 1200 °C. The effects of DVB and PCS content on the rheological properties of the solution and the morphological characteristics and the compressive strengths of SiC ceramics were investigated. The use of DVB and the resulting chemical cross-linking yielded modified pore characteristics and much lower oxygen content in pyrolyzed SiC compared to the conventional thermal curing method. A compressive strength of 18.7 MPa was obtained for pyrolyzed SiC prepared with 20 wt% PCS and a 0.2 DVB/PCS mass ratio. [ABSTRACT FROM AUTHOR]

A comparative study was performed by solid phase microextraction and capillary gas chromatography to establish the ability of four polymer sorbents of different compositions to extract and concentrate volatile organic compounds from the gas phase above an aqueous solution. All polymer sorbents sorbed nonpolar monoterpene hydrocarbons via a cooperative mechanism with almost equal and high efficiency. Sorbents based on polymethyl disiloxane and its mixture with divinylbenzene were more effective in extracting acetates and sesquiterpenes. As the concentration of these compounds in the gas phase increased, their binding by sorbents decreased. It was found that the determination of polar compounds depended on the presence of a solvent in the system. Compounds that are highly soluble in water (alcohols, ketones, etc.) had low coefficients of distribution between gas and water phases. Consequently, their sorption to any of the polymer sorbents was negligible. In the absence of the solvent, the degree of their extraction from the gas phase above the sample was high. It was shown that the actual composition of compounds in the initial mixture of essential oils could significantly differ from their composition in the gas phase. This method is convenient and informative for the purpose of studying the composition of volatile compounds in the gas phase that determine the flavor of the product. [ABSTRACT FROM AUTHOR]