Benzyltriethylammonium Chloride Research Articles

Kinetic investigation on palladium‐catalyzed carbonylation of allyl alcohol

AbstractPalladium‐catalyzed carbonylation of allyl alcohol to 3‐butenoic acid has been investigated. A significant effect of halide promoters, p‐tolylsulfonic acid (TsOH), water, solvents, and PPh3 concentration activity and selectivity has been studied. Detailed kinetics of this reaction was investigated in a temperature range of 363–383 K. The influence of parameters such as stirring speed, allyl alcohol, catalyst, benzyltriethylammonium chloride (BTEAC), TsOH concentrations, and CO partial pressures on the activity and selectivity has been studied. An empirical rate equation was suggested and found to be fairly consistent with observed rate data. In addition, the activation energy and kinetic parameters were evaluated.

Microscopic mechanism investigation of extraction of lignin by benzyltriethylammonium chloride-based deep eutectic solvents

Benzyltriethylammonium chloride (BTEAC)-based deep eutectic solvent (DES) has a high delignification rate in the pretreatment of lignocellulose, and the lignin obtained from the removal has the advantages of high purity and low molecular weight. The interaction mechanism between BTEAC-based DES and lignin at molecular level was investigated by multiscale simulation analytical approach. By analyzing the types of weak interaction, charge distribution, number of hydrogen bonds, energy distribution and density distribution in different systems, the influence of six hydrogen bond donor (HBD) structures on the extraction process was clarified. The interaction between Cl- and lignin is mainly electrostatic interaction, and the interaction between BTEA+ and lignin is mainly van der Waals (vdW) interaction. The original π-π stacking of lignin is replaced by the new π-π stacking between BTEA+ and lignin. The effects of different functional groups and length of carbon chain on the interaction were researched. The acidic HBD with short carbon chain has a larger interaction and can affect the ether bond on the lignin. Among them, due to the smaller volume of formic acid (FA), it provides more space for BTEA+ to contact with lignin, resulting in stronger interaction. The molecular-level theoretical foundation underpinning the efficacy of BTEAC-FA in lignin removal during the pretreatment process is provided.

Strukturelle Einblicke in die Terpencyclasedomänen Zweier Pilzlicher Sesterterpensyntasen und Enzymengineering zur Diversifizierung von Sesterterpenen

AbstractÜber die Strukturen und katalytischen Mechanismen von Sesterterpensynthasen (StTSs) ist wenig bekannt, was das strukturbasierte Engineering von StTSs zur Erweiterung der strukturellen Diversität von Sesterterpenen erheblich erschwert. Wir berichten hier über die Kristallstrukturen der Terpencyclisierungsdomänen (TC) von zwei pilzlichen StTSs: der Sesterfisherol‐Synthase (NfSS) und der Sesterbrasiliatrien‐Synthase (PbSS). Beide TC‐Strukturen enthalten Benzyltriethylammoniumchlorid (BTAC), Pyrophosphat (PPi) und Magnesiumionen (Mg2+), wodurch die katalytisch aktiven Zentren klar definiert sind. Eine Kombination aus Theorie und Experimenten, einschließlich der Modellierung carbokationischer Intermediate, ortsgerichteter Mutagenese und Isotopenmarkierungen, lieferte detaillierte Einblicke in die strukturellen Grundlagen der katalytischen Mechanismen. Strukturbasiertes Engineering von NfSS und PbSS führte zur Bildung von 20 Sesterterpenen, darunter 13 neue Verbindungen und vier Epimerpaare mit unterschiedlichen Konfigurationen an C18. Diese Ergebnisse erweitern die strukturelle Vielfalt von Sesterterpenen und liefern wichtige Erkenntnisse für die zukünftige Forschung im Bereich der synthetischen Biologie.

Structural Insights Into the Terpene Cyclization Domains of Two Fungal Sesterterpene Synthases and Enzymatic Engineering for Sesterterpene Diversification.

Little is known about the structures and catalytic mechanisms of sesterterpene synthases (StTSs), which greatly hinders the structure-based engineering of StTSs for structural diversity expansion of sesterterpenes. We here report on the crystal structures of the terpene cyclization (TC) domains of two fungal StTSs: sesterfisherol synthase (NfSS) and sesterbrasiliatriene synthase (PbSS). Both TC structures contain benzyltriethylammonium chloride (BTAC), pyrophosphate (PPi), and magnesium ions (Mg2+), clearly defining the catalytic active sites. A combination of theory and experiments including carbocationic intermediates modeling, site-directed mutagenesis, and isotope labeling provided detailed insights into the structural basis for their catalytic mechanisms. Structure-based engineering of NfSS and PbSS resulted in the formation of 20 sesterterpenes including 13 new compounds and four pairs of epimers with different configurations at C18. These results expand the structural diversity of sesterterpenes and provide important insights for future synthetic biology research.

Theoretical and experimental study of molecular interactions between constituents of deep eutectic solvents

In this study, we aimed to elucidate the molecular interactions in deep eutectic solvents (DESs) and acquire additional experimental evidence to increase our understanding of the molecular mechanisms responsible for the preparation of DES. We investigated three N-methylthiourea (NMTU)-based DESs with choline chloride (ChCl), allyltrimethylammonium chloride (ATMAC), and benzyltriethylammonium chloride (BTEAC) as hydrogen bond acceptors (HBA). To accomplish this, we used both experimental techniques including isopiestic, differential scanning calorimetry (DSC), and FTIR measurements as well as molecular dynamics (MD) simulations. The thermal behaviors of the prepared DESs were investigated by DSC method. In order to study the interaction and hydrogen bonding between the DESs constituents, FT-IR analysis and isopiestic measurements were carried out. Constant solvent activity lines of ternary HBA + HBD + solvent mixtures were determined by the isopiestic technique. The large positive deviation of the isosolvent activity lines from the semi-ideal behavior indicates a strong interaction between HBA and HBD, which is much stronger than HBA-HBA and HBD-HBD interactions. Classical MD simulations were performed at 298.15 K to analyze the nanoscopic properties and structure of the DESs. To investigate the interaction between the components and visualize the three-dimensional structure of the DESs, radial distribution functions (RDFs), coordination numbers (CNs), and combined (CDFs), and spatial (SDFs) distribution functions were determined by MD simulations. The obtained theoretical results confirmed the importance of hydrogen bonds in the preparation of DESs and also showed that these systems exhibit different structural arrangements. MD simulations were also used to determine the density of the DESs and the results showed good agreement with the experimental density.

Insights into application of aqueous biphasic systems of deep eutectic solvents composed of benzyltrialkylammonium chloride in dye separation

Deep eutectic solvents (DES) are considered the newest entry in the list of green solvents and they are analogues of ionic liquids (ILs), with excellent solvent characteristics better than commonly used organic solvents and ILs. Owing to this, We have prepared DES using benzyltrialkylammonium chloride (BTAAC) including benzyltrimethylammonium chloride (BTMAC), benzyltriethylammonium chloride (BTEAC), and benzyltributylammonium chloride (BTBAC) as hydrogen bond acceptors (HBA) and glycols, like ethylene glycol (EG), diethylene glycol (DEG) and triethylene glycol (TEG) as hydrogen bond donors (HBD). Aqueous biphasic systems (ABS) were developed using the synthesized DESs and K3PO4, K2HPO4, and K2CO3 at 298.15 K and atmospheric pressure. The phase-forming ability of DES has been evaluated based on the nature of potassium salts, HBA and HBD. In most cases, the influence of salts on ABS formation was found to follow the order: K3PO4 > K2HPO4 > K2CO3, while HBAs follow: BTBAC > BTEAC > BTMAC. The performance of the ABSs was experimentally applied for the extraction of Methyl orange (MO), Eriochrome black T (EBT), and Eosin Y (EY). In most ABS, the extraction order for the studied dyes noticed was: MO < EBT < EY, consistent with their hydrophobic nature. ABS consisting of BTBAC:TEG + K2HPO4 and BTBAC:TEG + K3PO4 was found to lead to the complete extraction of MO, EBT, and EY. The recovery of extracted EY dye was performed by adsorption method using starch-modified chitosan as an adsrobent.

Application of Aromatic Ring Quaternary Ammonium and Phosphonium Salts–Carboxylic Acids-Based Deep Eutectic Solvent for Enhanced Sugarcane Bagasse Pretreatment, Enzymatic Hydrolysis, and Cellulosic Ethanol Production

Deep eutectic solvents (DESs) with a hydrophobic aromatic ring structure offer a promising pretreatment method for the selective delignification of lignocellulosic biomass, thereby enhancing enzymatic hydrolysis. Further investigation is needed to determine whether the increased presence of aromatic rings in hydrogen bond receptors leads to a more pronounced enhancement of lignin removal. In this study, six DES systems were prepared using lactic acid (LA)/acetic acid (AA)/levulinic acid (LEA) as hydrogen bond donors (HBD), along with two independent hydrogen bond acceptors (HBA) (benzyl triethyl ammonium chloride (TEBAC)/benzyl triphenyl phosphonium chloride (BPP)) to evaluate their ability to break down sugarcane bagasse (SCB). The pretreatment of the SCB (raw material) was carried out with the above DESs at 120 °C for 90 min with a solid–liquid ratio of 1:15. The results indicated that an increase in the number of aromatic rings may result in steric hindrance during DES pretreatment, potentially diminishing the efficacy of delignification. Notably, the use of the TEBAC:LA-based DES under mild operating conditions proved highly efficient in lignin removal, achieving 85.33 ± 0.52% for lignin removal and 98.67 ± 2.84% for cellulose recovery, respectively. The maximum digestibilities of glucan (56.85 ± 0.73%) and xylan (66.41 ± 3.06%) were attained after TEBAC:LA pretreatment. Furthermore, the maximum ethanol concentration and productivity attained from TEBAC:LA-based DES-pretreated SCB were 24.50 g/L and 0.68 g/(L·h), respectively. Finally, the comprehensive structural analyses of SCB, employing X-rays, FT-IR, and SEM techniques, provided valuable insights into the deconstruction process facilitated by different combinations of HBDs and HBAs within the DES pretreatment.

Fractionation and evaluation of light-colored lignin extracted from bamboo shoot shells using hydrated deep eutectic solvents

In this study, light-colored lignin was extracted from bamboo shoot shells (BSS) using a hydrated deep eutectic solvent (DES) pretreatment. The hydrated DES used in pretreatment consist of formic acid, benzyl triethylammonium chloride (BTEAC) and water. The pretreatment using a hydrated DES containing 30% water (H30) demonstrate efficient delignification (82.9%). Additionally, the hydrated DES protected the β-O-4 linkage from excessive cleavage and recondensation as well as keep the light-colored of lignin. Moreover, the hydrated DES extracted lignin exhibits superior antioxidant performance and tyrosinase inhibitory capacity compared to the control. Notably, incorporating 5% lignin of H30-extracted lignin into a commercial suncream led to a remarkable enhancement of the SPF value, elevating from 14.8 to 32.6. In summary, the proposed hydrated DES pretreatment method offers significant benefits for extracting light-colored lignin, thereby promoting the multifunctional application of lignin in cosmetics.

Insights into the physicochemical properties of newly synthesized benzyl triethylammonium chloride-based deep eutectic solvents

In order to utilize deep eutectic solvents (DESs) as a replacement for conventional organic solvents for different applications, a detailed understanding of their physicochemical properties is extremely important. In this study, several novel DESs based on benzyl-triethylammonium chloride (BTEA) as a hydrogen bond acceptor (HBA) and acids/or alcohols as hydrogen bond donors (HBDs) have been synthesized. DESs have been thoroughly characterized and investigated for their physicochemical properties viz. thermal stability, glass transition temperature, viscosity (η), surface tension (γ), refractive index (nD), density (ρ), speed of sound (u), and conductivity (κ) in a temperature range of 293.15–343.15 K. The effect of temperature, type of HBDs, and alkyl chain length of HBDs of the DESs on the physicochemical properties are critically examined and discussed. Viscosity data are fitted to Vogel-Fulcher-Tamman (VFT) and Arrhenius models. A linear model was used to fit surface tension (γ), density, refractive index, and speed of sound data whereas conductivity data were fitted to a nonlinear equation. Primary data on physicochemical properties have been used to estimate the viscous flow parameters (activation entropy, activation enthalpy, and free energy of activation) and other derived parameters such as lattice energy, standard entropy, molar volume, intermolecular free length, and isentropic compressibility. A relationship between molar conductivity and dynamic viscosity has been established to evaluate the ionicity of the synthesized DESs. Insights into the structure–property correlations are discussed in detail.

Dispersive liquid-liquid microextraction based on deep eutectic solvent doped with hydroxyethyl-β-cyclodextrin for the determination of sulfonamides in environmental waters

A novel method was pioneered for the enrichment of six sulfonamides (SAs) in environmental waters, i.e., vortex-assisted dispersive liquid–liquid microextraction based on hydroxyethyl-β-cyclodextrin doped deep eutectic solvent (VA-DLLME-HCDDES). A hydrophobic deep eutectic solvent (HDES) was synthesized and used as an extractant based on two reaction precursors (benzyltriethylammonium chloride and thymol), and the doping of hydroxyethyl-β-cyclodextrin (HE-β-CD). The addition of HE-β-CD to the HDES greatly enhanced the enrichment factor for SAs by 21.6%. For the first time, the HE-β-CD doped HDES was demonstrated to be a supramolecular ternary DES (SUPRATDES). A multivariant methodology of Plackett-Burman design followed by central composite design was employed to screen and optimize several influencing factors in the VA-DLLME-HCDDES procedures. Under optimized conditions, the VA-DLLME-HCDDES/HPLC-PDA method showed good linear range of 1.1–500 μg L−1 (r2 > 0.9996) with the limits of detection of 0.3–1.1 μg L−1. After verification of its reliability with a certified reference standard (81267a), the newly developed method was successfully applied for the trace-level detection of SAs in environmental waters with relative recoveries of 84–112%. Overall, the prominent advantages of the proposed method are free of dispersant, easy preparation of HCDDES, environmental benignity and high extraction efficiency. Thus, the newly developed method provides a good alternative to conventional approaches for detection of SAs.

Spectroscopic Study of the Interaction of Reactive Dyes with Polymeric Cationic Modifiers of Cotton Fabrics

Cotton cationization with low molecular weight or polymeric cationic modifiers allows the effective dyeing of cotton substrates with reactive dyes under salt-free and more environmentally friendly conditions. The current work focuses on the spectroscopic study of the intermolecular interactions, which dictate the physicochemical process associated with fabric dyeing. Water-soluble cationic copolymers of vinyl benzyl chloride (VBC) and vinyl benzyl triethylammonium chloride (VBCTEAM) have been used as cellulose cationic modifiers. Dye uptake was assessed using Remazol Brilliant Blue R and Novacron Ruby S-3B dyes. The study involves ATR-FTIR, UV-Vis, fluorescence, and XPS spectroscopy. The results of binary polymer-rich dye-polymer aqueous solutions or dye-polymer precipitates at stoichiometric charge-ratio revealed that the sulfonate/sulfate anions of the dyes interact with the cationic VBCTEAM units of the polymer via electrostatic interactions. Moreover, the comparative study of dye application on modified and unmodified fabrics suggests that, unlike the latter, where dyes are chemically bound to cellulose, electrostatic forces dominate the interaction of modified fabrics with dye molecules.

FIXATION OF DYE-TYPE RED AND BLUE INK HANDWRITING ON AGED PAPER

In this article, red and blue ink handwriting on aged paper was fixed by fixative to prevent handwriting from fading or diffusion during aqueous deacidification. Firstly, four fixatives were selected: polydimethyl ammonium chloride (PDDA), the quaternary ammonium salt of chitosan (HACC), cationic guar gum (CGG), and benzyl triethyl ammonium chloride (TEBAC) alcohol solution, according to their fixation effects on filter paper dyes, and derive the optimal composition ratio of the above four fixatives. Experimentally derived that PDDA has an excellent fixation effect on red ink handwriting, and HACC has an excellent fixation effect on blue ink handwriting. In addition, HACC also has a positive impact on the conservation of handwriting in real archives. The mechanical properties of aged paper were improved, and the paper fibers had no obvious change after the fixation and deacidification processes.

Enhancing saccharification of bamboo shoot shells by rapid one-pot pretreatment of hydrated deep eutectic solvent

In this work, a rapid one-pot hydrated deep eutectic solvent (DES) pretreatment was proposed to facilitate the conversion of carbohydrates from lignocellulosic biomass to monosaccharides. Specifically, the pure and hydrated DES based on benzyl triethylammonium chloride (BTEAC), formic acid (FA) and water was used to pretreat bamboo shoot shells (BSS) by microwave heating. The pretreated solid residues were enzymatically saccharified to produce fermentable sugars, and the hydrolyzed carbohydrates and lignin remained in the hydrolyzate. The results showed that the yield of monosaccharides from the hydrated DES hydrolyzate (193.7–228.4 g/kg) was significantly higher than that (45.9–66.1 g/kg) of pure DES. The 30% hydrated DES pretreatment achieved the best glucose yield (89.03%) and a total monosaccharides yield of 555.4 g/kg, which corresponded to a conversion ratio of carbohydrates to monosaccharides of 87.0%. The proposed process is a robust method for the efficiently convert carbohydrates from BSS into monosaccharides.

Exploration of Diverse Interactions of l-Methionine in Aqueous Ionic Liquid Solutions: Insights from Experimental and Theoretical Studies.

Here, we have investigated some physicochemical parameters to understand the molecular interactions by means of density (ρ) measurement, measurement of viscosity (η), refractive index(n D) measurement, and conductance and surface tension measurements between two significant aqueous ionic liquid solutions: benzyl trimethyl ammonium chloride (BTMAC) and benzyl triethyl ammonium chloride (BTEAC) in an aqueous l-methionine (amino acid) solution. The apparent molar volume (Φv), coefficient of viscosity (B), and molar refraction (R M) have been used to analyze the molecular interaction behavior associated in the solution at various concentrations and various temperatures. With the help of some important equations such as the Masson equation, the Jones-Doles equation, and the Lorentz-Lorenz equation, very significant parameters, namely, limiting apparent molar volumes (Φv 0 ), coefficient of viscosity (B), and limiting molar refraction (R M 0), respectively, are obtained. These parameters along with specific conductance (κ) and surface tension (σ) are very much helpful to reveal the solute-solvent interactions by varying the concentration of solute molecules and temperature in the solution. Analyses of Δμ1 0#, Δμ2 0#, TΔS 2 0#, ΔH 2 0#, and thermodynamic data provide us valuable information about the interactions. We note that l-Met in 0.005 molality BTEAC ionic liquid at 308.15 K shows maximum solute-solvent interaction, while l-Met in 0.001 molality BTMAC aqueous solution of ionic liquid at 298.15 K shows the minimum one. Spectroscopic techniques such as Fourier transform infrared (FTIR), 1H-NMR, and UV-vis also provide supportive information about the interactions between the ionic liquid and l-methionine in aqueous medium. Furthermore, adsorption energy, reduced density gradient (RDG), and molecular electrostatic potential (MESP) maps obtained by the application of density functional theory (DFT) have been used to determine the type of interactions, which are concordant with the experimental observations.

Aromatic volatile organic compounds absorption with phenyl‐based deep eutectic solvents: A molecular thermodynamics and dynamics study

AbstractThe suitability of phenyl‐based deep eutectic solvents (DESs) as absorbents for toluene absorption was investigated by means of thermodynamic modeling and molecular dynamics (MD). The thermodynamic models perturbed‐chain statistical associating fluid theory (PC‐SAFT) and conductor‐like screening model for real solvents (COSMO‐RS) were used to predict the vapor–liquid equilibrium of DES–toluene systems. PC‐SAFT yielded quantitative results even without using any binary fitting parameters. Among the five DESs studied in this work, [TEBAC][PhOH] consisting of triethyl benzyl ammonium chloride (TEBAC) and phenol (PhOH), was considered as the most suitable absorbent. Systems with [TEBAC][PhOH] had lowest equilibrium pressures of the considered DES–toluene mixtures, the best thermodynamic characteristics (i.e., Henry's law constant, excess enthalpy, Gibbs free energy of solvation of toluene), and the highest self‐diffusion coefficient of toluene. The molecular‐level mechanism was explored by MD simulations, indicating that [TEBAC][PhOH] has the strongest interaction of DES–toluene compared to the other DESs under study. This work provides guidance to rationally design novel DESs for efficient aromatic volatile organic compounds absorption.

BTEAC Catalyzed Ultrasonic-Assisted Synthesis of Bromobenzofuran-Oxadiazoles: Unravelling Anti-HepG-2 Cancer Therapeutic Potential through In Vitro and In Silico Studies.

In this work, BTEAC (benzyl triethylammonium chloride) was employed as a phase transfer catalyst in an improved synthesis (up to 88% yield) of S-alkylated bromobenzofuran-oxadiazole scaffolds BF1-9. These bromobenzofuran-oxadiazole structural hybrids BF1-9 were evaluated in vitro against anti-hepatocellular cancer (HepG2) cell line as well as for their in silico therapeutic potential against six key cancer targets, such as EGFR, PI3K, mTOR, GSK-3β, AKT, and Tubulin polymerization enzymes. Bromobenzofuran structural motifs BF-2, BF-5, and BF-6 displayed the best anti-cancer potential and with the least cell viabilities (12.72 ± 2.23%, 10.41 ± 0.66%, and 13.08 ± 1.08%), respectively, against HepG2 liver cancer cell line, and they also showed excellent molecular docking scores against EGFR, PI3K, mTOR, and Tubulin polymerization enzymes, which are major cancer targets. Bromobenzofuran-oxadiazoles BF-2, BF-5, and BF-6 displayed excellent binding affinities with the active sites of EGFR, PI3K, mTOR, and Tubulin polymerization enzymes in the molecular docking studies as well as in MMGBSA and MM-PBSA studies. The stable bindings of these structural hybrids BF-2, BF-5, and BF-6 with the enzyme targets EGFR and PI3K were further confirmed by molecular dynamic simulations. These investigations revealed that 2,5-dimethoxy-based bromobenzofuran-oxadiazole BF-5 (10.41 ± 0.66% cell viability) exhibited excellent cytotoxic therapeutic efficacy. Moreover, computational studies also suggested that the EGFR, PI3K, mTOR, and Tubulin polymerization enzymes were the probable targets of this BF-5 scaffold. In silico approaches, such as molecular docking, molecular dynamics simulations, and DFT studies, displayed excellent association with the experimental biological data of bromobenzofuran-oxadiazoles BF1-9. Thus, in silico and in vitro results anticipate that the synthesized bromobenzofuran-oxadiazole hybrid BF-5 possesses prominent anti-liver cancer inhibitory effects and can be used as lead for further investigation for anti-HepG2 liver cancer therapy.

Reduction of filler-filler interaction and hysteresis loss of carbon black filled rubber compound by using modified carbon Black

The carbon black, used in rubber compound as reinforcing filler, improves the strength, durability, and wear resistance of the rubber compound. However, it causes filler-filler interaction and results in extensive hysteresis energy losses on deformation. This research aims to reduce hysteresis energy loss of rubber compound by reducing filler-filler interaction and by improving the filler dispersion in rubber matrix. In this study, the effect of carbon black treated with benzyl tri-ethyl ammonium chloride (BTEAC) on solution styrene butadiene rubber and butadiene rubber (SSBR-BR) system was studied. Microscopic study of dispersion and distribution of carbon black in rubber matrix was performed and a significant improvement in dispersion of BTEAC treated carbon black in SSBR-BR rubber matrix was observed. As a result of increased interaction of BTEAC treated carbon black with rubber, the filler - filler interaction was significantly reduced, resulting lower hysteresis energy loss of the compound as expressed by loss tangent (tanδ) value and it has been observed that an extent of around 15% reduction in tanδ value was achieved in rubber compound consisting of BTEAC treated carbon black. In this research, the carbon black was treated with different concentration of BTEAC, such as 0.5%, 1% and 1.5% and the best balance of rubber properties was observed for 1% and 1.5% BTEAC treated carbon black.

Non-isothermal cure kinetics of an anhydride-cured cycloaliphatic/aromatic epoxy system in the presence of a reactive diluent

This paper reports on the non-isothermal cure kinetics of a cycloaliphatic/aromatic epoxy resin (Litestone 2210E) with tetrahydromethyl-1,3-isobenzofurandione (NADIC) initiated by benzyltriethylammonium chloride (BTEAC) obtained from different models using differential scanning calorimetry (DSC) data. The effects of an increase in the content (3.0 to 4.5 wt%) of the initiator BTEAC and the partial replacement (10 wt%) of the epoxy resin with reactive diluent 1,4-butanediol diglycidyl ether (BDDE) are addressed. The Avrami-Ozawa, autocatalytic and nth-order reaction kinetic models were evaluated. They yielded an exponent close to 1, showing that the epoxy systems under study have little autocatalytic dependence and can be described by a reaction-order model. The pre-exponential factor (ln A) and the activation energy (Ea) calculated using the autocatalytic and nth-order reaction models were reduced with an increase in the initiator content while the addition of the reactive diluent had no significant influence on these values. The activation energy remained practically constant over the cure conversion according to calculations made using the isoconversional methods of Friedman and Kissinger-Akahira-Sunose, and the average E¯α data were in agreement with values obtained with the other models. An approach based on the diffusion factor showed that diffusional effects due to vitrification become significant only at conversions (α) as high as 0.95, regardless of the initiator content and addition of the reactive diluent.

Polymerization of N-phenylmaleimide Using Different Catalysts

The polymerization of N-phenylmaleimide (N-PMI) employing sodium phosphate tribasic as a catalyst has been successfully investigated in this study. The effect of dimethyl sulfoxide (DMSO) solvent on the principal catalyst, sodium phosphate tribasic, was extensively studied. The effects of several catalysts, including tetrabutylammonium acetate (TBAA), 4-dimethylaminopyridine (DMAP), Benzyl triethylammonium chloride (BTEAC), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), 1-Methylimidazole (1MA) and potassium phthalimide salt on polymerization of N-PMI have been discussed in this study. Additionally, the kinetics of polymerization in DMSO with Na3PO4 as the initiator is investigated. By using 1H and 13C nuclear magnetic resonance (NMR) spectrum analysis, attenuated total Reflection-Fourier transform infrared (ATR-FTIR), the resultant polymers were identified. Thermogravimetric and differential scanning calorimetric analyses were used to study the thermal behaviors. Our results prove that a salt form of catalyst can initiate the polymerization of N-PMI in dimethyl sulfoxide at a suitable concentration and under favorable conditions.

A 3D uranyl phosphonate framework: Structure, characterization, and fluorescence performance

A three-dimensional uranyl phosphonate framework [BTA][(UO2)3(TppmH)(H2O)3]•0.75H2O (UPF-109) (Tppm = tetrakis[4-(dihyroxyphosphoryl)phenyl]methane, BTA = benzyltriethylammonium chloride) has been synthesized using the hydrothermal method. The structure of UPF-109 shows that dimers and monomers are connected to give a two-dimensional layer, and Tppm ligands link the layers to give a 3D structure with two types of channels. To provide more detailed information, PXRD, TG, IR, UV-vis, and photoluminescence were performed. In addition, the relation between fluorescence intensity and temperature demonstrates the potential application of UPF-109 in fluorescence temperature sensors.