Solubility In Toluene Research Articles

Improving the spinnability of mesophase pitch and its carbon fiber performance by modifying toluene solubles content in the precursor

Improving the spinnability of mesophase pitch and its carbon fiber performance by modifying toluene solubles content in the precursor

Direct ink writing‐based additive manufacturing of styrene‐isoprene‐styrene block copolymer

AbstractThermoplastic elastomer (TPE) is a hybrid polymeric material with immense potential for industrial application due to its unique elasticity, processability, and excellent mechanical properties. However, 3D printing of TPEs using fused deposition modeling (FDM) is challenging due to their poor layer coalescence, high melt viscosity, and weak column strength. In the present work, styrene‐isoprene‐styrene (SIS) block copolymer, a commercially available TPE material, was successfully 3D printed using a direct ink writing (DIW)‐based additive manufacturing process to enhance its design flexibility. The rheology of the prepared inks has a great influence on the printability, layer formability, and resolution of the 3D printed parts. Hansen's solubility criteria were used exclusively, to investigate the most suitable solvent to prepare the inks for the DIW technique, implying better solubility of toluene than THF. This is in line with experimental results that the 3D printed specimens from SIS/toluene inks demonstrate higher stretchability, elastic modulus and tensile strength over the 3D printed specimens from the SIS/THF inks. It has been shown that the selection of a suitable ink and the optimum level of SIS concentration is essential for the successful fabrication of parts using DIW to make them suitable for end use.Highlights The DIW process has been investigated for 3D printing of SIS block copolymers. The rheology of the developed inks has a great influence on printability and layer formability. The 3D printed samples showed high elongation at break, elastic modulus, and tensile strength.

Simultaneously Enhanced Chain Flexibility, Three Dimensional Printability, and Reduction of Shrinkage Stress in Biodegradable and Photocurable Multiblock Copolymers

A library of biodegradable and photocurable poly(propylene fumarate)-co-poly(trimethylene carbonate) (PPF-co-PTMC) multiblock copolymers encompassing the entire composition range and various block lengths has been designed and synthesized. By combining experiments and atomistic molecular dynamics simulations, we reveal the effects of chain architectures such as composition and block lengths on the thermal, rheological, and printing properties of these copolymers. The introduction of flexible PTMC blocks, which are found to be highly miscible with PPF blocks, into the unentangled copolymer backbone dramatically expedites chain relaxation, lowers the activation energy, and enhances the solubility in toluene. The chain flexibility of the copolymers is positively correlated with the composition of PTMC, while the block length of either PPF or PTMC affects little. Thus, lower values in glass transition temperature Tg, zero-shear viscosity η0, printing speed, and shrinkage stress in photocuring are consistently seen at higher compositions of PTMC. Photocurable PPF-co-PTMCs can be printed into high-precision 3D objects. This study provides a series of novel biopolymers and also a guideline to design photocurable polymers used in biomedical implants.

Hybrid Films from Blends of Castor Oil and Polycaprolactone Waterborne Polyurethanes.

Waterborne polyurethanes (WBPUs) with relatively high biobased content (up to 43.7%) were synthesized, aiming at their use as coatings for metals and woods. The study was performed on self-standing films obtained from anionic polyurethane water dispersions (PUDs). The initially targeted PUD was prepared from castor oil (CO), while tartaric acid (TA), a byproduct of wine production, was utilized as the internal anionic emulsifier. Although the films were cohesive and transparent, they were fragile, and thus blending the CO-TA PUD with other WBPUs was the chosen strategy to obtain films with improved handling characteristics. Two different WBPUs based on polycaprolactone diol (PCL), a biodegradable macrodiol, were prepared with dimethylolpropionic acid (DMPA) and tartaric acid (TA) as synthetic and biobased internal emulsifiers, respectively. The use of blends with PCL-TA and PCL-DMPA allowed for tailoring the moduli of the samples and also varying their transparency and haze. The characterization of the neat and hybrid films was performed by colorimetry, FTIR-ATR, XRD, DMA, TGA, solubility and swelling in toluene, and water contact angle. In general, the addition of PCL-based films increases haze; reduces the storage modulus, G’, which at room temperature can vary in the range of 100 to 350 MPa; and reduces thermal degradation at high temperatures. The results are related to the high gel content of the CO-TA film (93.5 wt.%), which contributes to the cohesion of the blend films and to the crystallization of the PCL segments in the samples. The highest crystallinity values corresponded to the neat PCL-based films (32.3% and 26.9%, for PCL-DMPA and PCL-TA, respectively). The strategy of mixing dispersions is simpler than preparing a new synthesis for each new requirement and opens possibilities for new alternatives in the future.

Customized Orthogonal Solvent System with Various Hole-Transporting Polymers for Highly Reproducible Solution-Processable Organic Light-Emitting Diodes.

Recently, various hosts and emitters for solution-processable thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) have been developed. However, a few studies have been conducted on hole transport materials (HTMs) with differentiated solubility characteristics for manufacturing multilayer OLEDs using a solution process. Here, three new hole transport (HT) styrene polymers, PICz, PPBCz, and PTPCz, were synthesized by radical polymerization. Each of the polymers exhibited increases in their highest occupied molecular orbital (HOMO) levels and better hole-transporting abilities than poly(9-vinylcarbazole) (PVK) as a reference HT polymer. Furthermore, the three HT polymers exhibited different solubilities in toluene. Therefore, it was not possible to use a toluene solution to prepare the emitting layer (EML). To overcome this problem, ethyl acetate (EA), in which the three HT polymers are insoluble, was used as an orthogonal solvent to prepare an EML solution. In EA-solution-processed green-emitting TADF-OLEDs, the three HT-polymer-based devices displayed somewhat low turn-on voltages of 2.8 V and high external quantum efficiencies (EQEs) of >23%. These values are superior to those of a device with a PVK-HT layer. In addition, the devices manufactured with the EA solution showed high-performance reproducibility owing to the stable formation of each layer. In this study, we removed the HTM solubility constraint by dramatically changing the solvent for preparing the EML solution and provided an efficient strategy for the fabrication of OLED devices via solution processes in the future.

Intermolecular Interactions of Pyrene and Its Oxides in Toluene Solution.

In this work, the conformer-rotamer ensemble sampling tool (CREST), with the underlying semiempirical GFN2-xtb method, was used for automated geometry exploration of the homodimers of pyrene, pyrene-4,5-dione, and pyrene-4,5,9,10-tetraone, along with the heterodimer of pyrene and pyrene-4,5,9,10-tetraone. Geometries and energies of the dimers were further refined at the ωB97X-D4/def2-TZVP level of theory, both in the gas phase and in toluene solution. Computations in solution were handled using the CPCM (conductor-like polarizible continuum model) and SMD (solvation model based on density) models. Two previously unidentified pyrene-homodimer conformations were identified, and the effects of oxidation on the geometries and energies of dimerization were explored; in general, oxidation leads to stronger intermolecular interactions and decreased solubility in toluene. For selected dimers, DLPNO-CCSD(T)/cc-pVTZ/SMD(Toluene) energies were determined at the DFT geometries and illustrated the accuracy of the ωB97X-D4 approach, with an MAD of 1.47 kJ/mol.

Quorum sensing improved the low-temperature performance of biofilters treating gaseous toluene

Biofilters usually have poor VOC removal performance at temperatures lower than 20 °C. In this study, two quorum sensing (QS) enhancement methods, which are addition of exogenous N-acyl-homoserine lactones (AHLs) and inoculation of AHL-producing bacteria, were applied in biofilters treating gaseous toluene at a low temperature of 12 °C. Their effects on biofilter performance and biofilm characteristics were investigated. The results showed that adding exogenous AHLs and AHL-producing bacteria in biofilters raised the average toluene elimination capacity by 39% and 26% respectively, and raised the average mineralization efficiency by 25% and 47% respectively in first 24 days. In addition, the two QS enhancement methods could increase the attached biomass by 48% and 87% respectively and made the biofilm distribute more uniform by increasing its extracellular polymeric substances content and microbial adhesive strength. The two QS enhancement methods resulted in more mesopores in biofilm, lower O/C and (O+N)/C of organic elements in biofilm, and increased the solubility of toluene in liquid phase, which all benefit VOCs mass transfer in biofilters. These results demonstrate that QS enhancement methods have the potential to optimize the biofilm and thus improve the performance of biofilters treating VOCs at a low temperature. This work provides us a new choice to improve industrial-scale biofilters treating VOCs at high latitude regions or in winter.

Chiral Bicyclic Imidazole-Catalyzed Direct Enantioselective C -Acetylation of Indolones

Chiral Bicyclic Imidazole-Catalyzed Direct Enantioselective <i>C</i> -Acetylation of Indolones

Molecular representation of coal-derived asphaltene based on high resolution mass spectrometry

The asphaltene separated by solubility in small molecular alkanes and toluene is the most structurally diverse and complex components in heavy oil, such as vacuum residue and coal tar. The coal-derived asphaltene is always regard as a succession of maltene fraction from small molecules to large molecules, and also a continuum of island- and archipelago-type structures, which is difficult to be identified accurately through current characterization methods. This limits the further study of molecular dynamics and reaction dynamics simulation of asphaltenes. In this work, a representation model of molecular composition and structure for coal-derived asphaltene is developed mainly based on Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) coupled with collision induced dissociation (CID) and traditional methods of nuclear magnetic resonance spectroscopy (13C NMR), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS). Island- and archipelago-type structures are considered qualitatively in the representation of asphaltene. The asphaltene molecules are systematic assembled using stochastic algorithms and optimized by simulated annealing algorithm according to the group contribution method. The bulk properties for simulating asphaltenes are in good agreement with the experimental results giving acceptable predictions for the composition and structure of the asphaltenes. Moreover, the representative average structure asphaltene molecules are obtained using the developed molecular similarity function, which could be applied in the further study of molecular aggregation simulation and reaction kinetics simulation.

Treatment of toluene gaseous streams using packed column electro-scrubbers and cobalt mediators

• Toluene was efficiently removed from gases using the electro-scrubbers. • Low faradaic efficiencies because of low solubility of toluene in the absorbent. • Mediated electro-oxidation mechanisms promoted by the presence of cobalt. • Current density needs to be balanced according to polluted gas flowrate. An absorption system has been combined with an electrochemical cell to treat a gaseous stream polluted with toluene. Toluene retention in 3 h operation tests was higher than 87.0% in the case of treating the gaseous stream with single scrubbing, 97.0% in the case of using electro-scrubbing and over 99.0% in using cobalt-mediated electro-scrubbing. It was found that the amount of toluene that escapes from the electro-scrubber does not only depend on the flow rate but also on the current density and the presence of the metallic mediator. The higher the current densities are, the higher the amount of electrochemically degraded toluene is. In addition to the mediating effect of the metal catalyst, the results also suggest an important participation of the redox sulfate/persulfate pair in the degradation of toluene. Only methyl-cyclohexane (at very low concentrations) is observed as intermediate, despite carboxylic acids were also initially expected. The formation of this compound can be explained in terms of the hydrogenation of toluene. The very low concentrations absorbed, and the very high current densities, support the occurrence of an electrochemical cold combustion in the electro-scrubber.

Hydrophobic deep eutectic solvents as attractive media for low-concentration hydrophobic VOC capture

Emissions of volatile organic compounds (VOCs) are known to be significant human health and ecological risks. Absorption is a classical process applied to eliminate air pollutants, yet the removal efficiency of gaseous contaminants is often curbed by the mass transfer resistance between absorption liquids and hydrophobic VOCs. This work aims to evaluate the feasibility of capturing VOCs from exhaust through the use of hydrophobic deep eutectic solvents (DESs). Among the examined DESs, hydrophobic DESs whose hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are both fatty acids with long alkyl chains (i.e., decanoic acid [DecA] and lauric acid [LauA]) achieve the highest absorption capacity of toluene at 9.94 mg toluene per g DES at 30 °C and 800 ppm toluene with an HBA:HBD molar ratio of 1:3. Hydrophobic interactions between the fatty acids and toluene are critical for improving the VOC absorption ability of DESs, as the toluene solubility increases with an increase in the alkyl chain length of the fatty acid eutectics. The compiled results suggest that effective hydrophobic VOC removal can be realized by the proposed hydrophobic fatty acid eutectics, [LauA][DecA], and the physical absorption nature of toluene in fatty acid eutectics benefits facile recovery and recycling.

Insight into pore structures evolution and applications in lithium-sulfur battery of pitch fractions-based activated carbons

Difference in composition of pitch determines the porosity of pitch-based activated carbons on a large scale. Toluene-soluble (TS), toluene-insoluble and pyridine-soluble (PS), pyridine insoluble (PI) fractions were separated by extracting pitch with different solvents followed by the activation using alkali KOH to obtain porous carbons which were used as sulfur host materials. It is found that different fractions possess different reactivity which mainly relies on the molecular weight and structures. The light component TS, equipped with more active sites, tends to be activated to porous carbon with well-developed pores and it promotes the optimal distribution of sulfur compared to heavy fractions PS and PI. When used as sulfur host, TS-based carbon displays better electrochemical performance compared to PS/PI-based carbon. The relationship between the structure and electrochemical performance of fraction-based porous carbon has been established. The findings provide a method for judging and regulating the structure and electrochemical performance of porous carbons derived from pitch-based precursors.

One-pot amination of cyclohexanone-to-secondary amines over carbon-supported Pd: Unraveling the reaction mechanism and kinetics

• Catalytic transformation of cyclohexanone into secondary amines. • A reaction map for the catalytic amination of cyclohexanone is proposed. • A kinetic model describing the amination of cyclohexanone is elucidated. • The effect of temperature, reactant concentrations and H 2 -equivalents is assessed. The liquid phase amination of the cyclohexanone (CyO) with aniline (PhNH 2 ) was studied on a Pd/C catalyst using NaCO 2 H as a H-donor. Catalytic tests were performed in batch reactors by varying reactant concentrations (0, 0.1, 0.2 and 0.4 mol/L), the temperature (80–160 °C) and H 2 -equivalents availability (0, 2 and 4 H 2 -equivalents with respect to CyO). The results indicate that, the use of NaCO 2 H barely affect the reactivity (measured as initial reaction rate) while it does influence the selectivity to secondary amines. This effect was ascribed to the limited effectivity of the H 2 transfer, which was controlled by the water formed after the condensation of the CyO with the PhNH 2 , hydrogen solubility in toluene, and the mass transfer from the liquid to the catalyst surface. The experimental observations were consistent with a multi-step mechanism consisting in: a first step of condensation of the ketone and the amine to form an imine, followed by the disproportionation of the imine into secondary amines. The kinetic measurements at initial rate conditions were well interpreted by a Langmuir Hinshelwood (L-H) kinetic model, which suggest that the surface reaction to form the intermediary imine is the rate limiting step (R.L.S).

Liquid‐crystalline behavior and thermal conductivity of vinyl polymers containing benzoxazole side groups

AbstractA series of methacrylamides containing benzoxazole (BO) mesogenic side groups and different lengths of alkyl units was synthesized in this study. A methacrylamide containing the n‐dodecyl group was selected as a suitable monomer to obtain beneficial thermally conductive polymeric materials because of its sufficient solubility in toluene in the subsequent radical polymerization and because of its liquid crystallinity. This methacrylamide led to a highly soluble polymer with film‐forming ability. The BO‐containing polymethacrylamide also exhibited liquid‐crystalline (LC) behavior during the heating and cooling processes. The cast film was kept at a slightly lower temperature than the clearing temperature and quenched to room temperature. This procedure afforded a film maintaining optical anisotropy at room temperature, implying that a frozen LC structure is maintained at room temperature. The quenched film also resulted in a significantly enhanced thermal conductivity (λ = 0.60 W m−1 K−1) without the aid of fillers and external fields, unlike the as‐cast counterpart without optical anisotropy. A polyacrylate containing a flexible long alkylene (C6) spacer between the main chains and a BO‐containing mesogenic side group was also investigated. The polyacrylate exhibited LC behavior during the heating and cooling processes over wide ranges. The polyacrylate film quenched from an established temperature, which contains a frozen LC structure, also exhibited a significantly enhanced λ value (0.63 W m−1 K−1) without fillers and external fields. Thus, the BO‐containing vinyl polymers studied in this work are promising candidates for novel heat‐releasing materials. © 2020 Society of Chemical Industry

Synthesis and two-photon properties of phenothiazine-based dendrimers with tetraphenylmethane cores

We have synthesized two new two-photon active dendritic molecules with tetraphenylmethane core with four phenothiazine-based arms. They show good solubility in organic solvents, including dichloromethane, chloroform, toluene and tetrahydrofuran. It is found that the two dendrimers display strong two-photon absorption and two-photon excited up-conversion fluorescence at 800 nm. • Two new phenothiazine-based dendrimers with tetraphenylmethane cores have been synthesized. • The dendritic molecules display two-photon absorption activity. • The two-photon absorption cross section increased with the increasing of the conjugation degree.

Solubility determination and thermodynamic modelling of Progesterone in twelve pure solvents and three binary solvents at 278.15 to 323.15 K

The solubility of Progesterone at T = 278.15–323.15 K was measured by static equilibrium method combined with HPLC in twelve solvents (methanol, ethanol, isopropanol, n-propanol, n-butanol, acetone, tetrahydrofuran, 1,4-dioxane, n-heptane, ethyl acetate, acetonitrile, and toluene) and three binary solvents (tetrahydrofuran + n-heptane, 1,4-dioxane + n-heptane, and toluene + n-heptane). The results showed that progesterone has the highest solubility in toluene (0.2249 in mole fraction) and other low-dielectric constant solvents, and the smallest in n-heptane (1.120 × 10−4 in mole fraction). Moreover, the solubility increases as the temperature rise both in pure and mixed solvents. As expected, the DSC and XRDP results showed that there was no crystal form difference between the raw material and all the precipitate. Herein, the Modified Apelblat model, Buchowski-Ksiazaczak λh model, Jouyban-Acree model, CNIBS/R-K model, and SUN model were employed to fit the experimental data. As a result, the maximum RAD doesn't exceed 5.0%, and the maximum RMSD was less than 0.1%. Furthermore, we chose KAT-LSER model to explore the solubility of progesterone and the solute-solvent interaction relationships. The results showed that when hydrogen bond acidity and polarizability/dipolarity of solvents increases, the solubility of progesterone increases. Meanwhile, comparing the experimental data and the fitting results, it can be concluded that the experimental data was reliable and almost consistent with the fitting results. Furthermore, it also proved that the above mentioned five thermodynamic equations were advantageous and trustworthy.

Sorption of Benzene, Toluene, and Ethylbenzene by Poly(ethyl methacrylate) and Plasticized Poly(ethyl methacrylate) at 298.15 K Using a Quartz Crystal Microbalance

Solubilities of benzene, toluene, and ethylbenzene (BTEX compounds, together with xylene) in poly(ethyl methacrylate) (PEMA) and plasticized PEMA at 298.15 K were measured using a quartz crystal microbalance and are reported in the form of solvent activity versus solvent weight fraction. Two plasticizers, diisononyl cyclohexane-1,2-dicarboxylate (DINCH) and diisooctyl azelate (DIOA), were studied, each at three different concentration levels in the polymer. The presence of a plasticizer increases the solubility of all three compounds. Data were interpreted using a pseudobinary Flory–Huggins model in which the plasticized polymer is considered to be a single pseudocomponent.

Synthesis and Physicochemical Properties of 2,7-Disubstituted Phenanthro[2,1-b:7,8-b']dithiophenes.

We report the design, synthesis, and physicochemical properties of an array of phenanthro[2,1-b:7,8-b’]dithiophene (PDT-2) derivatives by introducing five types of alkyl (CnH2n+1; n = 8, 10, 12, 13, and 14) or two types of decylthienyl groups at 2,7-positions of the PDT-2 core. Systematic investigation revealed that the alkyl length and the type of side chains have a great effect on the physicochemical properties. For alkylated PDT-2, the solubility was gradually decreased as the chain length was increased. For instance, C8-PDT-2 exhibited the highest solubility (5.0 g/L) in chloroform. Additionally, substitution with 5-decylthienyl groups showed poor solubility in both chloroform and toluene, whereas PDT-2 with 4-decylthienyl groups resulted in higher solubility. Furthermore, UV-vis absorption of PDT-2 derivatives substituted by decylthienyl groups showed a redshift, indicating the extension of their π-conjugation length. This work reveals that modification of the conjugated core by alkyl or decylthienyl side chains may be an efficient strategy by which to change the physicochemical properties, which might lead to the development of high-performance organic semiconductors.

Study of the toluene absorption capacity and mechanism of ionic liquids using COSMO-RS prediction and experimental verification

As green solvents, ionic liquids (ILs) are quite suitable for the absorption of volatile organic compounds (VOCs) such as benzene and its homologues. However, solvent selection is the key to the VOC absorption process. In the present study, a rapid solvent screening tool, Conductor-like Screening Model for Real Solvents (COSMO-RS), was used to predict the solubility of toluene in 816 ILs. The effects of four structure characters, namely, the type and alkyl chain length of the cations and anions on the solubility of toluene were discussed. The following conclusions were drawn from the results: (1) ILs with pyrrolidinium-based cations showed better solubility than pyridinium- and imidazolium-based ones. (2) The solubility of toluene in PF6-based ILs increased with the increasing alkyl chain length, while its solubility in Ac-based ILs exhibited the opposite trend. (3) Toluene showed greater solubility in Cl-based ILs than those based on other anions. (4) The solubility of toluene increased with the anion alkyl chain length. Ac-based ILs were chosen as the most promising potential solvents, and further studied to determine the relationship between various interaction energy parameters and toluene solubility. The results showed that the misfit energy played a dominant role during the absorption process. Furthermore, several ILs were selected for experimental verification of the predicted solubility behavior using liquid and gaseous toluene. The results demonstrated that COSMO-RS could be used to semi-quantitatively and qualitatively predict the solubility of toluene, and this model had promising prospects in screening ILs for VOCs absorption. In summary, this study provided a fundamental basis and practical data for the control and treatment of VOCs.

Structural design of asymmetric diketopyrrolopyrrole polymers for organic solar cells processed from a non-halogenated solvent

Diketopyrrolopyrrole (DPP) polymers possess narrow optical bandgaps and high charge carrier mobilities which make them attractive for solar cell applications. DPP polymers are generally only soluble in chlorinated solvents, which is a drawback for commercial application. Solubility in non-halogenated solvents can be achieved by reducing the translational symmetry of the chain by employing two different aromatic moieties on either side of the DPP units. Here a series of polymers in which thiophene (T) and pyridine (Py) sandwich the DPP units in the main chain is reported. These asymmetric T-DPP-Py units increase the solubility dramatically. The side chain length, nature of the co-monomer, and regioregularity of the main chain are varied to investigate their effect on the solubility in toluene, the active layer morphology and the performance of organic solar cells. We demonstrate that polymers processed from both chloroform and toluene reach very similar power conversion efficiencies and blend morphologies. In general, a small co-monomer, short side chains, a regioregular main chain, and a high molecular weight give the best performance for solar cells processed from toluene. • Asymmetric substitution enhances solubility of diketopyrrolopyrrole polymers. • The asymmetry enables processing from non-halogenated solvents. • In solar cells, power conversion efficiencies are similar for both types of solvents. • Regioregular derivatives provide higher efficiencies than regiorandom polymers.