Increasing Chain Length Research Articles

Bis‐peri‐dinaphtho‐rylenes: Facile Synthesis via Radical‐Mediated Coupling Reactions and their Distinctive Electronic Structures

AbstractPolycyclic aromatic hydrocarbons (PAHs) with a one‐dimensional (1D), ribbon‐like structure have the potential to serve as both model compounds for corresponding graphene nanoribbons (GNRs) and as materials for optoelectronics applications. However, synthesizing molecules of this type with extended π‐conjugation presents a significant challenge. In this study, we present a straightforward synthetic method for a series of bis‐peri‐dinaphtho‐rylene molecules, wherein the peri‐positions of perylene, quaterrylene, and hexarylene are fused with naphtho‐units. These molecules were efficiently synthesized primarily through intramolecular or intermolecular radical coupling of in situ generated organic radical species. Their structures were confirmed using X‐ray crystallographic analysis, which also revealed a slightly bent geometry due to the incorporation of a cyclopentadiene ring at the bay regions of the rylene backbones. Bond lengh analysis and theoretical calculations indicate that their electronic structures resemble pyrenacenes more than quinoidal rylenes. That is, the aromatic sextets are predominantly localized along the long axis of the skeletones. As the chain length increases, these molecules exhibit enhanced electronic absorption with a bathochromic shift, and multiple amphoteric redox waves. This study introduces a novel synthetic approach for generating 1D extended PAHs and GNRs, along with their structure‐dependent electronic properties.

Synthesis and mesomorphic properties of bent liquid crystals containing triazole mesogenic unit with terminal flexible alkyl chain and laterally ethoxy substituted Schiff base

ABSTRACT A new series of bent-shaped liquid crystals containing a triazole ring were synthesised and characterised at ambient and elevated temperatures. The triazole-cored and bent liquid crystals possess a flexible alkyl chain at one terminal, while the other side of the core is connected by a laterally ethoxy Schiff base consisting of a CN-biphenyl moiety. The evaluation on optical and thermal properties was carried out by polarising optical microscope and differential scanning microscope which revealed the length of the alkyl chain, –CnH2n + 1, that influenced the mesophase and the related clearing temperatures (Tc). Whilst the compounds with higher number of n possess lower Tc points, the presence of SmA phase seemed to be more favourable for the compounds in which the alkyl chain length was n ≥ 12. This observation can be associated with its bending angle and charge distributions along the two arms of which the interaction between the opposite counterparts of both arms in these bent-liquid crystals would promote the formation of SmA phase. The computational calculations based on density functional theory were performed to further support the transition from non-mesomorphic to SmA phases upon the increase in alkyl chain length (n), dipole moment and polarity which contribute to its stability.

Molecular dynamics simulation study of the effect of molecular structure of warm mix additive on lubricating properties

Based on tribological theory, molecular dynamics (MD) simulation is used to characterize the lubrication behavior of warm mix additive at the friction interface between asphalt and aggregate from the molecular scale. The base asphalt lubricating film model and the warm mix asphalt lubricating film model were established respectively. The asphalt-mineral interfacial shear friction system was constructed using two types of lubricating film models and SiO2 (001) friction surface. The effects of shear rate, system temperature and the hydrophobic end carbon chain length of the warm mix additive on the lubricating property of the simulated system were investigated, and the mechanism of warm mix additive was further revealed. The results show that the higher the shear rate, the greater the shear stress on the surface of the lubricating film. The shear stress on the surface of the warm mix asphalt lubricating film is significantly smaller than the base asphalt lubricating film. The system temperature has no noticeable effect on the shear stress. Additionally, with increasing hydrophobic end carbon chain length of the warm mix additive, the shear stress of the warm mix asphalt lubricating film decreases. The temperature of the lubricating film gradually rises from the interface to the inside, reaching a maximum value at the film's centre. The temperature inside the base asphalt lubricating film rises with an increasing shear rate. In contrast, the temperature distribution inside the warm mix asphalt lubricating film is relatively constant within a specific range. The cohesive energy of asphalt lubricating film and its adsorption energy on the SiO2 surface both decrease with an increasing shear rate, and the temperature has little effect on the cohesive energy and adsorption energy. With the increase of the hydrophobic end carbon chain length of the warm mix additive, the adsorption energy of warm mix asphalt lubricating film increases and then decreases, the self-diffusion coefficient decreases first and then increases, and the cohesive energy increases gradually. The number density distribution shows a stronger affinity between warm mix additive and SiO2. In conclusion, this paper reveals the lubrication mechanism of surfactant warm mix additive, which can provide reference and guidance for subsequent scholars to further study the warm mixing mechanism by MD method, as well as for the study of asphalt-aggregate interfacial behavior.

Evaluation of calf thymus DNA binding of newly synthesize five 9 [sbnd]O[sbnd] Imidazolyl alkyl berberine derivative: A comparative multi-spectroscopic and calorimetric study

DNA binding with small molecule plays an important role in the designing of various anticancer drugs with greater efficacy. The five 9-O-imidazolyl alkyl berberine derivatives (BI) of different chain length has been synthesized and fully characterized. The binding study of calf thymus DNA with these newly synthesized berberine derivative was performed using various biophysical techniques. The binding affinity of BI to calf thymus DNA increased with increasing the chain length. The binding constant value obtained from UV–Vis spectral analysis was 1.84x105for BI1, 2.01x105for BI2, 1.51 × 106 for BI3, 3.66 × 106 for BI4, 6.68 × 106. Partial intercalative binding with strong stabilization of the DNA helix was revealed from circular dichroism spectral study and viscosity measurement. From the ITC experiment it was revealed that the bindings of BI1, BI2, BI3, BI4 and BI5 to calf thymus DNA were favoured by a large positive favourable entropy and negative enthalpy change and the highest spontaneity found for BI5. With the increase in chain length the binding was driven by a stronger entropy term with a higher binding constant indicates involvement of hydrophobic force for all these interaction. High binding affinities of calf thymus DNA with berberine-imidazole derivatives might be helpful for new drug design.

Effect of hydrophobic chain length on the properties of polycarboxylate polymeric surfactants

In this work, a series of polycarboxylate polymeric surfactants were designed and synthesized from acrylate monomers with different alkyl chain lengths (alkyl chain lengths of 1, 4, 6, 12, 18), epoxy succinic acid (ESA), acrylic acid (AA) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS). Their structures were confirmed by FT-IR, 1H NMR and GPC. A series of surfactant parameters, including critical micelle concentration (CMC), minimum surface tension, surface tension reduction at critical micelle concentration (Πcmc), surface tension reduction efficiency (pC20), etc, were obtained by surface activity test. The results showed that with the increase of the alkyl chain length of acrylate, surface tension and CMC of polycarboxylate polymeric surfactants gradually decreased. When the alkyl chain length of acrylate monomer was 12, the surface tension of polycarboxylate polymeric surfactants was the lowest, which was 32.6 mN/m. The results of TG, DLS and TEM showed that with the increased of the alkyl chain length of the acrylate, the micellar size of polycarboxylate polymeric surfactants decreased regularly. Meanwhile, the foaming, wetting and emulsifying properties of polycarboxylate polymeric surfactants were positively correlated with the alkyl chain length of the acrylate. The dispersing ability of polycarboxylate polymeric surfactants for calcium carbonate was 101.5 mg/g, which can dispersed Fe2O3 fouling to less than 1 μm under the condition of 0.6 g/L.

Local and Large-Scale Conformational Dynamics in Unfolded Proteins and IDPs. I. Effect of Solvent Viscosity and Macromolecular Crowding.

Protein/solvent interactions largely influence protein dynamics, particularly motions in unfolded and intrinsically disordered proteins (IDPs). Here, we apply triplet-triplet energy transfer (TTET) to investigate the coupling of internal protein motions to solvent motions by determining the effect of solvent viscosity (η) and macromolecular crowding on the rate constants of loop formation (kc) in several unfolded polypeptide chains including IDPs. The results show that the viscosity dependence of loop formation depends on amino acid sequence, loop length, and co-solute size. Below a critical size (rc), co-solutes exert a maximum effect, indicating that under these conditions microviscosity experienced by chain motions matches macroviscosity of the solvent. rc depends on chain stiffness and reflects the length scale of the chain motions, i.e., it is related to the persistence length. Above rc, the effect of solvent viscosity decreases with increasing co-solute size. For co-solutes typically used to mimic cellular environments, a scaling of kc ∝ η-0.1 is observed, suggesting that dynamics in unfolded proteins are only marginally modulated in cells. The effect of solvent viscosity on kc in the small co-solute limit (below rc) increases with increasing chain length and chain flexibility. Formation of long and very flexible loops exhibits a kc ∝ η-1 viscosity dependence, indicating full solvent coupling. Shorter and less flexible loops show weaker solvent coupling with values as low as kc ∝ η-0.75±0.02. Coupling of formation of short loops to solvent motions is very little affected by amino acid sequence, but solvent coupling of long-range loop formation is decreased by side chain sterics.

Long-chain amino acids and hydrogen bonding enhanced epoxy thermosets: High latency, thermal and mechanical properties, and its application in recyclable carbon fiber composites

Thermoset carbon fiber reinforced polymer (CFRP) composites are widely used and in increasing demand in composites industries. Among them, CFRP with one-component epoxy matrix can optimize the preparation process. However, high-value carbon fiber (CF) is difficult to recover and no cases of latent CFRP with CF recyclability have been reported. In this study, long aliphatic chains were innovatively introduced into amino acid type latent curing agents to improve the latent performance and the solubility in organic solvents. The latent performance of curing agents improved with the increase of chain length due to the difficulty in proton transfer of ammonium ions along to the long chain. The latent curing agent derived from 1,10-diaminodecane exhibited good solubility in ethanol and good compatibility with epoxy monomers, making it had the potential for industrial use in the preparation of CFRP. Moreover, amide bonds in the synthetic amino acid were prone to form hydrogen bonds to improve the thermal and mechanical properties of cured resin, while ester bonds in the amino acids imparted the resin with degradability in alkaline environments, thereby endowing CFRP with CF recyclability without damaging surface morphology and chemical structure. This work will open a door for the recycling research of latent CFRP.

Spatial mapping and quantitative evaluation of protein corona on PEGylated mesoporous silica particles by super-resolution fluorescence microscopy

Nanoparticles (NPs) adsorb serum proteins when exposed to biological fluids, forming a dynamic protein corona that has a profound impact on their overall biological profile and fate. Polyethylene glycol (PEG) modification is the most widely used strategy to mitigate and inhibit protein corona formation. Nevertheless, the accurate mapping and quantification of PEG inhibition effects on protein corona formation have scarcely been reported. Herein, we demonstrate the direct observation and quantification of protein corona adsorbed onto PEGylated mesoporous silica particles by direct stochastic optical reconstruction microscopy (dSTORM). The variation tendency of protein penetration depth in terms of PEG molecular weights and incubated time is investigated for the first time. The maximum penetration depths present slight increase with the prolonged incubation time, while they tend to remarkably decrease with increased chain length of modified PEG. Moreover, the co-localization of preformed protein corona with lysosomes and the destination of adsorbed protein are demonstrated. Our method provides important technical characterization information and in-depth understanding of protein corona adsorbed onto PEGylated mesoporous silica particles. This shines new light on the behaviors of silica materials in cells and may promote their practical applications in biomedicine.

Retention and transport of PFOA and its fluorinated substitute, GenX, through water-saturated soil columns

Perfluoro-2-propoxypropanoic acid (GenX) has emerged as a substitute for perfluorooctanoic acid (PFOA) especially since PFOA was listed among the persistent organic pollutants (POPs) by the Stockholm Convention in 2019. However, limited knowledge exists regarding the behavior and mobility of GenX in natural soils hindering the prediction of its environmental fate. This study investigated the mobility and retention of GenX and PFOA in soils under batch and water-saturated flow-through conditions. Batch experiments revealed that GenX has a lower binding affinity to soil than longer-chained PFOA, potentially threatening groundwater resources. Unlike metal-oxides/minerals (ferrihydrite, gibbsite and manganese dioxide), biochar (BC) and activated carbon (AC) amendments significantly enhanced the sorption of both GenX and PFOA in soil. Sorption data on minerals and carbonaceous materials implied that for shorter-chained GenX, the predominant mode of sorption was through electrostatic (ionic) interactions, while for longer-chained PFOA, hydrophobic interactions became progressively more important with increasing chain length. The dynamic flow experiments demonstrated that these soil amendments enhanced the retention of both compounds, thereby decreasing their mobility. Simultaneous injection of both compounds into columns pre-loaded with either PFOA or GenX increased their retardation. GenX sorption was more affected by pre-sorbed PFOA compared to the minimal impact of pre-loaded GenX on PFOA sorption. A newly developed reactive transport model, which incorporates a two-site sorption model and accounts for kinetic-limited processes, accurately predicted the sorption and transport of both compounds in single and binary contamination systems. These findings have important implications for predicting and assessing the fate and mobility of per- and polyfluoroalkyl substances (PFAS) in soils and groundwaters.

Synthesis and properties of amide-based cationic gemini surfactants with semi-rigid spacer

Abstract A series of novel gemini surfactants (m-E2Ph-m) with ester groups and a benzene ring as rigid spacer were synthesized and characterized by IR, 1H NMR and Mass spectrometry. The effect of hydrophobic chain length on the surface properties and aggregation behavior of the gemini surfactants were investigated by the measurements of surface tension, electrical conductivity, fluorescence. The critical micelle concentration (CMC) of these surfactants decreases with increasing alkyl chain length. The thermodynamic parameters exhibited that the micellization was a spontaneous and exothermic process in environment. The micellization process became more beneficial with the increase of alkyl chain length and the decrease of temperature.

Amylose complexation with diacylglycerols involves multiple intermolecular interaction mechanisms

Molecular complexation mediated by amylose can delay the oxidation of diacylglycerol (DAG) but the mechanism remains unclear, and little attention has been paid to starch–DAG complexes (SDCs). Herein, SDCs with different chain lengths (12−18 carbons) were prepared via co-precipitation and the underlying complexation mechanism was comprehensively explored. The results revealed nano-scale (∼150−500 nm) features and fewer weakly bound DAGs of SDCs with increasing chain length, attributed to complicated interchain and/or intrachain crosslinking with complexing indices ranging from 73% to 91%. X-ray diffraction, differential scanning calorimetry and thermogravimetry analysis unveiled the involvement of tight and weak intermolecular interaction mechanisms between starch and DAGs, and the former exhibited higher short-range structure order, confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy. Molecular dynamics simulation showed that amylose tended to form V6-type helices around dimyristoyl- and distearoyl-glycerol with average helical cavity sizes of 9.4 and 11.3 Å, respectively, predominantly driven by hydrophobic interactions. SDCs significantly enhanced the oxidative stability of DAGs and delayed the in vitro starch digestion rate. The findings provide a paradigm for the intensive processing of DAGs to improve their oxidative stability and health-promoting efficacy.

Fabrication and Characterization of Sulfonated Carbon Materials and Chitosan-Derived Functioned Carbon via Schiff’s Base Process for Separation Purposes

The Schiff bases reaction is applied to form various functioned carbon structures using renewable carbon from waste sources, Chitosan, 4-Amino-3-hydroxy-napthalene-1-sulphnic acid, and dimethyl amino benzaldehyde as starting materials. The formed functioned carbons were characterized by TEM, FTIR, XRD, and surface area analysis to assess their morphology, structure, porosity, and surface functional groups. In addition, the chromatographic-based thermodynamic analysis is applied to evaluate the surface energy and thermodynamic parameters during the separation of hydrocarbon species. Results indicated the formation of various carbon structures in convex-like shapes with diameters between 600 nm and 1500 nm, including side-building edges of diameter between 100 nm and 316 nm. The formed functioned carbon surfaces are rich with O-H, N=C, C=C, C=O, and C=S groups, as indicated by the FTIR. The function carbons are named carbon coated with Chitosan-derived covalent organic layer (C@Chitosan-COL) as well as Schiff’s base-derived sulfonated carbon (Schiff’s-C-S) in relation to the applied starting materials. The chromatographic-based thermodynamic analysis showed that the entropy changes of adsorption (ΔSA) increased with increasing chain length demonstrating less random movement and higher adsorption in both materials. The fabricated C@Chitosan-COL and Schiff’s-C-S showed an efficient separation of hydrocarbon mixture including n-Nonane, n-Decane, n-Undecane, and n-Dodecane.

Exposure to per- and polyfluoroalkyl substances in women with twin pregnancies: Patterns and variability, transplacental transfer, and predictors

The extensive exposure to per- and polyfluoroalkyl substances (PFASs) has raised public health concerns. The issue of PFAS exposures in women with twin pregnancies remains unresolved. To determine exposure profiles, the transplacental transfer efficiencies (TTEs) of PFASs and predictors were estimated. We found that serum PFASs were widely detected, with detection rates of over 50% for 12 PFASs in maternal serum throughout pregnancy. The majority of PFAS levels exhibited fair to good reproducibility (ICCs > 0.40). Moderate to low correlations were observed for most PFASs between twin cord serum and maternal serum at three trimesters (rs = 0.13–0.77, p values < 0.01). We first presented a U-shaped trend for TTEs with increasing chain length for perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) in twins, even in twin sex subgroups. Further, we found that PC4 and PC5 (indicators of exposure to PFHxS and 6:2 Cl-PFESA) were positively associated with age (β = 0.85, 1.30, and 1.36, respectively). Our findings suggested that there is moderate variability among certain PFASs and that these PFASs have the ability to cross the placental barrier. Exposure patterns were found to be associated with maternal age.

First mesomorphic and DFT characterizations for 3- (or 4-) n-alkanoyloxy benzoic acids and their optical applications

New liquid crystalline hydrogen bonded 3- (or 4)-n-alkanoyloxy benzoic acids were synthesized and probed theoretically and experimentally. The molecular structures of these compounds were elucidated by proton NMR, carbon-13 NMR and elemental analyses. Differential scanning calorimetry (DSC) was used to investigate the thermal and mesomorphic properties of all the symmetrical dimers that bearing identical alkanoyloxy chains. Moreover, polarized optical microscopy (POM) was used to determine their mesophases. The findings show that all the designed symmetrical dimers exhibit the smectic mesophase with relative thermal stability that depends on the length of their terminal side chain. Additionally, the experimental findings of the mesomorphic behavior are further supported by DFT calculations. The alkanoyloxy benzoic acid para-derivatives (In) were shown to be more stable than their meta-substituted (IIn) analogues due to stronger hydrogen bonding interactions. The computed reactivity parameters showed that the position of ester moiety has a significant impact on the acids reactivity. The absorbance spectra of both the 3- (or 4)-n-alkanoyloxy benzoic acids revealed a blue shift with the increment of the of alkyl chain size; however, the energy band gaps of 3-n-alkanoyloxy benzoic derivatives were found to be slightly higher than those of the 4-n-alkanoyloxy benzoic acids. Moreover, the photoluminescence spectrum of the prepared materials is rather broad, and exhibited a red shift as the alkyl chain length increases. The fluorescence lifetime shown to rise as alkyl chain length grows longer, and 3-n-alkanoyloxy benzoic acids have slightly longer lifetime compared to their 4-n-alkanoyloxy benzoic analogues.

Revealing the factors resulting in incomplete recovery of perfluoroalkyl acids (PFAAs) when implementing the adsorbable and extractable organic fluorine methods

Per- and polyfluoroalkyl substances (PFASs) are environmental contaminants of concern. Techniques that quantify total organic fluorine (TOF) such as the adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF) methods are important for PFAS risk assessments. The objective of this study was to systematically evaluate each step of the AOF (loading, washing, combustion) and EOF (loading, washing, elution, combustion) methods for the recovery of ten ultrashort-, short-, and long-chain unsubstituted perfluoroalkyl acids (PFAAs). We measured the overall recovery of fluoride for each method for each PFAA, and the recovery of each PFAA around the loading, washing, and elution steps. We also measured the combustion efficiency of each PFAA by direct combustion. The overall AOF and EOF recovery ranged from 9.3%–103.3% to 21.0%–108.1%, respectively, with higher recoveries measured for PFAAs with increasing chain length in both methods. The three ultrashort-chain PFAAs (trifluoroacetic acid, perfluoropropionic acid, and perfluoropropanesulfonic acid) exhibited the lowest overall recoveries from 9.3–25.2% for AOF and 21.0–51.5% for EOF. We found that decreases in the overall recovery are the result of losses of ultrashort- and short-chain PFAAs during the washing step and the incomplete mineralization of perfluoroalkyl sulfonic acids during combustion for AOF and incomplete elution of short- and long-chain PFAAs and the loss of ultrashort-chain PFAAs during the washing step for EOF. Our data suggest that the EOF method is more appropriate than the AOF method for measuring TOF in samples containing ultrashort- and short-chain PFAAs and that methodological improvements are possible with a focus on the washing, elution, and combustion steps.

Effect of molecular environment on asphaltene aggregation: a molecular dynamics study

Asphaltene deposition poses a significant threat to the safe production of crude oil as it tends to occur in forming porous media, wellbores, pipelines, and refining equipment. It is also responsible for the high viscosity of crude oil, making it challenging to recover heavy crude oil. This study investigates the impact of aliphatic chain length on asphaltene aggregation and the molecular properties of organic solvents and dispersants interacting with asphaltenes. To achieve this, two model asphaltenes, M1 and C5Pe, were used in molecular dynamics simulations using radial distribution function, root means square displacement, diffusion coefficient, solubility parameter, cohesion energy density, and interaction energy as characterization parameters. The simulations revealed that the aggregation onset of C5Pe and M1 occurs at 2–5 Å at room temperature and pressure, and π–π stacking is the primary mode of aggregation, with the presence of heteroatomic groups providing additional forces for stable aggregation. Additionally, it was found that the π–π interactions weakened with the increase of the side chain length. The study also investigated the molecular behavior of asphaltenes in six organic solvents and found that M1 was more soluble in aromatic solvents than C5Pe, and undesirable solvents could induce asphaltene aggregation. Furthermore, the effect of five dispersants on asphaltene aggregation was explored, with PIBSI, BEHP, B-DBSA, CTAB, and benzoic acid showing decreasing dispersing ability in that order at lower concentrations. However, at higher concentrations, the effect of some dispersants diminishes and triggers self-aggregation behavior.

Expanding polymeric feedstocks for powder bed fusion via rational control of liquid–liquid phase separation

AbstractPowder bed fusion (PBF) is a promising technology in polymeric additive manufacturing, whose growth is inhibited by limited material options. In this manuscript, we report the use of thermally induced phase separation (TIPS) to controllably produce polymer powders of polypropylene that are suitable for PBF. Moreover, these studies provide crucial insight into the factors that govern the final size of the produced powder, offering fundamental insight that fosters the rational control of powder fabrication for PBF. More precisely, the impact of polymer concentration, molecular weight, and quench temperature on the size of the powder is demonstrated, where the particle size increases with solution concentration, quench temperature and molecular weight. The molecular weight dependence is consistent with a decrease in polymer solubility with an increase in chain length, while the solution concentration dependence can be explained by the relative fractions of the two phases in the precipitation process of polymer solutions. Careful analysis of the temperature and solution concentration dependence of the powder verifies that droplet coalescence is the governing mechanism in the phase separation‐based particle formation process. Therefore, this fundamental understanding provides pathways to use TIPS to produce powders suitable for PBF from a broad range of polymer solutions.

The effects of structural variations in neutral phosphorus extractants on UO22+ extraction behavior and radiation stability: Experimental and theoretical insights

In the present work, the effects of four neutral phosphorus extractants (TBP, TAP, THP, TEHP) with different molecular structures on the extraction behaviors towards U(Ⅵ) and radiation stability were systematically studied. The results of the batch extraction and the γ-radiolysis experiments manifested that the extraction performance and radiation stability of the four extractants followed the order of TEHP > THP > TAP > TBP. Moreover, DFT calculations and Multiwfn software were utilized to analyze the properties of the extractants. The electrostatic potentials (ESP) and frontier molecular orbital of extractants indicated that the nucleophilic ability was ranked as TEHP > THP > TAP > TBP. The analyses of quantum theory of atoms in molecules (QTAIM) and Wiberg indices (WBIs) revealed that the UO22+ ions exhibited stronger complexation ability with O atoms in TEHP compared to the other three extractants. The bonds between UO22+ ions and extractants were primarily ionic in nature. From the energetic perspective, the thermodynamic energy demonstrated that the Gibbs free energy of TEHP in aqueous solution was the most negative, implying that it should be easier to combine with UO22+. This work elucidates that the increase of alkyl chain length and the presence of branched chains can enhance the extraction performance and radiation stability of neutral phosphorus extractants. It not only lays the theoretical foundation for designing novel organic phosphorous extractants with superior extraction performance and high radiation stability, but also provides scientific basis for the extraction process of uranium in spent nuclear fuel reprocessing.

Adsorption of quaternary ammonium salt hydrophobic modifiers on the α-quartz (001) surface: a density functional theory study

To investigate the adsorption mechanism of quaternary ammonium salt on the α-quartz (001) sur-face, the adsorption models of hydrophobic modifiers 1231, 1431, 1631 and 1831 were constructed and simulated using the density functional theory (DFT). Results indicate that the adsorption energy of quaternary ammonium salt increases with the increase of carbon chain length, and the adsorption energy reaches the maximum at 18 carbon atoms; however, the adsorption capacity of 1631 is weak owing to the carbon chain deflection. Based on the Mulliken bond population analysis, reagent 1831 has the strongest interaction with α-quartz (001) surface compared with 1231, 1431 and 1631; and during the adsorption process, charge transfer and electrostatic attraction occur between the reagent and α-quartz (001) surface with similar degrees of charge transfer observed. This study emphasizes that electrostatic attraction plays a key role in the adsorption process, while the week hydrogen bonding plays a secondary role.

Experimental and molecular dynamics simulation study of the ionic liquids’ chain-length on wetting of bituminous coal

Controlling coal dust pollution is confronted with numerous challenges in the demanding environment of deep mining. Chemical additives, imidazolium ionic liquids (ILs), have been considered an effective strategy to boost the hydrophilicity of coal and reduce dust emissions. This work conducted experiments with molecular dynamics (MD) simulation to study the wetting characteristics of ILs ([Emim][Cl], [Bmim][Cl], and [Hmim][Cl]) with different chain-length on coal. The static wettability tests results indicated that the wettability of ILs was improved as the chain-length increased, and the wettability on bituminous coal followed the rule of water<[Emim][Cl]<[Bmim][Cl]<[Hmim][Cl]. The dynamic dust suppression experiments in the roadway showed that the dust suppression efficiency of 2% [Hmim][Cl] reached 77.5%, 2.45 times that of water. The ESP and frontier orbital energy show that the chain-length increase can enhance the ILs activity. The MD results indicated that short-chain ionic liquid ([Emim][Cl]) tends to accumulate on the surface of coal molecules, whereas long-chain ionic liquid ([Hmim][Cl]) possesses the capability to permeate coal molecules and serves as a tunneling role between coal and water, thereby enhancing the hydrophilicity of bituminous coal. The research results could be used to determine and design ILs with excellent wetting performance for improving the coal dust suppression effect.