Influence Of Alkyl Chain Length Research Articles

Long-chain alkyl emulsifiers induced asphalt particle dispersion: Lipophilicity-enhancement effect

The structure of the lipophilic groups within the emulsifiers plays a pivotal role in uniformly dispersing the asphalt particles in the water regarding the storage and thermal stability of emulsified asphalt. This study combines laboratory experiments with molecular dynamics simulations, investigating the influence of alkyl chain length on emulsified asphalt dispersion and behavior at the oil/water interface. The results reveal that long-chain alkyl emulsifiers (C16TAC and C18TAC) present a lipophilicity-enhancement effect. This phenomenon increases the free volume fraction of emulsified asphalt, reducing viscosity and improving the compatibility of emulsion. This results in smaller asphalt particle sizes (D50 = 1.982μm) and more uniform dispersion. Vigorously lipophilic long-chain alkyl promotes emulsifier molecular migration towards the asphalt phase, thickening the oil/water interfacial layer and reducing interfacial tension and energy by more than 90 %. Notely, long-chain alkyl emulsifiers establish strong hydrogen bonds with water molecules, leading to water molecule aggregation into a hydration layer. Laboratory experimental results demonstrate that this lipophilicity-enhancement effect significantly improves the storage and thermal stability of emulsified asphalt. This research recommends long-chain alkyl emulsifiers in developing and designing energy-efficient pavement engineering regarding high-performance emulsified asphalt.

Formation and evolution of nanobubbles in CH4-H2O-Alcohol system: Insight into the effect of alcohol chain length from molecular dynamics simulations

Nanobubbles (NBs) which are gas filled cavities of nanometre dimensions present in liquids attracted increasing attention in the recent years due to their application in various fields such as chemistry, biology, medicine etc. An important aspect of NB research is the study of effect of additives on formation and evolution of these bubbles. The present study examined by applying molecular dynamics simulations, the formation and evolution of methane NBs in the CH4-H2O-Alcohol system, which is known to form during alcohol induced dissociation of CH4 hydrates in the natural gas extraction process. The effect of alcohol type and concentration on NB formation and evolution was examined through simulations of CH4-H2O-CH3OH, CH4-H2O-C2H5OH and CH4-H2O-nC3H7OH systems. The study revealed that increase in both concentration and the alkyl chain length of alcohols promoted NB formation. Alcohol molecules are found to enhance NB nucleation through accumulation near the NB-liquid interface resulting in a decrease in the surface tension (γ) at the interface. These effects become more pronounced as the alkyl chain length increases which explains the enhanced NB formation in systems containing nC3H7OH and C2H5OH compared to those containing CH3OH. The mechanism of formation and evolution of NBs is found to significantly depend on the type of alcohol present. NBs are found to nucleate at multiple locations in the systems containing nC3H7OH and C2H5OH which eventually coalesce to form a single large stable NB. In the presence of NBs which vary significantly in size, bubble growth was also found to occur through Ostwald ripening which involves transfer of CH4 from smaller NB to the larger one. In contrast, in the CH4-H2O-CH3OH system, primarily a single NB nucleated which grew in size through absorption of CH4 molecules dissolved in the liquid, rather than through coalescence or Ostwald ripening. The observed influence of alcohol type on the process of NB evolution is explained by examining the influence of alkyl chain length on γ and diffusivity of CH4 molecules. Due to the role of NBs on methane hydrate regeneration from the hydrate melt, we examined the influence of NB in the CH4-H2O-Alcohol system on the organization of water molecules (HSWs) present in the hydration shell of dissolved CH4. The value of F4 order parameter of HSWs and the number of hydrogen bonded water rings in the hydration shell of CH4 were analysed. The value of F4 order parameter indicate that the hydrophobic alkyl chain of alcohol induced hydrate like arrangement of HSWs, which is more pronounced in the case of alcohol with longer alkyl chain. However, alcohol molecules are also found to dislodge HSWs around CH4 resulting in a decrease in the number of water rings around dissolved CH4 which is not conducive to hydrate formation. These observations are consistent with the reported dual effect of alcohol on hydrate formation with alcohol promoting hydrate formation at low concentrations and inhibiting at high concentrations.

Influence of Alkyl Chain Length on the Performance of Inverse Emulsion Polyacrylamide Fracturing Fluid Thickeners

Influence of Alkyl Chain Length on the Performance of Inverse Emulsion Polyacrylamide Fracturing Fluid Thickeners

Molecular mechanism of influence of alkyl chain length in ionic surfactant on the wettability of low rank coal

Molecular mechanism of influence of alkyl chain length in ionic surfactant on the wettability of low rank coal

Influence of Alkyl Chain Length of Alcohols on the Extraction Efficiency of 3-Methoxybutyl Acetate in Aqueous Solution (C5–C8 as Examples): Experimental Study, Thermodynamic Modeling, and Molecular Interaction Analysis

Influence of Alkyl Chain Length of Alcohols on the Extraction Efficiency of 3-Methoxybutyl Acetate in Aqueous Solution (C₅–C₈ as Examples): Experimental Study, Thermodynamic Modeling, and Molecular Interaction Analysis

Influence of alkyl chain length and temperature on the densities, viscosities and speeds of sound of binary liquid mixtures of {2-methyl-1-butanol + 2-ethoxyethanol, or 2-propoxyethanol, or 2-butoxyethanol} at T = (298.15, 303.15 and 308.15) K

Density (ρ), viscosity (η) and speed of sound (u) of pure components and binary mixtures of 2-methyl-1-butanol with alkoxyethanols viz., 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol have been measured over the entire range of composition at different temperatures T = (298.15, 303.15 and 308.15) K. Using the experimental data various thermophysical properties such as excess molar volume (VmE), excess molar isentropic compressibility (Ks,mE), excess speed of sound (uE), deviation in viscosity (Δη) and excess Gibb’s free energy of activation for viscous flow (ΔG∗E) have been calculated. The excess or deviation properties used to define the molecular interactions between like and unlike components. Further, the values of excess and deviation properties have been fitted to the Redlich-Kister polynomial equation. The measured viscosities have been correlated with various semi-empirical relations such as Grunberg-Nissan, Tamura-Kurata, Hind et al., Katti-Chaudhri, McAllister (three body interaction) model, Heric-Brewer and McAllister (four body interaction) model. Apart from this, Prigogine–Flory–Patterson (PFP) theory is also used for the estimation of VmE values for studied binary mixtures.

Can sodium 1-alkylsulfonates participate in the sodium dodecyl sulfate micelle formation?

The aggregation behavior of sodium dodecyl sulfate (SDS) was studied in an aqueous solution in the presence of increasing concentrations of selected sodium 1-alkylsulfonates, namely sodium 1-octanesulfonate, sodium 1-decanesulfonate, and sodium 1-dodecanesufonate. The critical micelle concentration (CMC) of SDS was determined by conductivity and fluorescence intensity measurements. The steady-state fluorescence quenching experiments with pyrene as a fluorescent probe were performed to obtain micellar aggregation numbers (Nagg) of the surfactant. The thermodynamic parameters of micellization (ΔGmic0 for all studied systems; ΔHmic0 and ΔSmic0 for sodium 1-dodecanesufonate) have been determined and compared. The influence of alkyl chain length and concentration of the selected sodium 1-alkylsulfonates on the values of CMC, Nagg, ΔGmic0, ΔHmic0, and ΔSmic0 of SDS has been discussed. As it was found, all selected for the experiments electrolytes decrease significantly the CMC of the surfactant, while an opposite effect is observed for Nagg values. The obtained experimental results have been supported by theoretical calculations. Interestingly, it has been proven that solely the molecules of sodium 1-dodecanesufonate (of the same carbon chain length) may act as the SDS mimetics – they are not recognized by SDS as the ones with a different structure and consequently are allowed to participate in the formation of the surfactant’s micelles.

Influence of alkyl chain length on the photovoltaic properties of dithienopyran-based hole-transporting materials for perovskite solar cells

A tailored design of asymmetric hole-transporting materials (HTMs) is reported with the synthesis of a family of new HTMs based on the use of the 5H-dithieno[3,2-b:2′,3′-d]pyran (DTP) moiety endowed with donor p-methoxytriphenylamines.

Probing the influence of alkyl chain length on the aggregation behaviour of some naphthalene sulphonamide derivatives through spectroscopic and microscopic studies

With an aim to understand the role of alkyl chain length in tuning the optical properties of the organic aggregates, several naphthalene sulphonamide derivatives with different alkyl chain lengths have been synthesized. Molecular systems are used to fabricate different aggregates. Aggregation behaviour of the systems has been investigated by exploiting spectroscopic and microscopic technique. Investigations have revealed that the aggregates formed by shorter alkyl chain containing derivatives exhibit blue-shifted absorption and emission (as compared to respective monomer) to form H-aggregate whereas longer alkyl chain containing derivatives exhibit red-shifted absorption and emission (as compared to respective monomer) to form J-aggregate.

Effects of length and type of the alkyl chain on the micellization behavior of mixed systems of HS15 with fatty acids

Due to volatility, low solubility and instability, the application of SCFAs and MCFAs is limited, which is expected to be solved by micelles. Taking SCFAs and MCFAs as models, this paper aims to research the influences of alkyl chain length and type on HS15 micelles. The critical micelle concentration (CMC) of various acid-HS15 systems was determined firstly. Then some air–water interface parameters and thermodynamic parameters were analyzed. Subsequently, particle size, cloud points (CP) and fluorophore release curves were measured. With the increase of CMC and Gmin, the decrease of size and CP, and the rapid quenching of fluorophores, it is more difficult for acids with longer-chain to form stable micelles with HS15 because of the strength of iceberg structure. Showing smaller CMC and Gmin, smaller size, higher CP and slower release of fluorescers, branched molecules can bind more closely to the hydrophobic part of HS15 due to their spatial flexibility.

Both alkyl chain length and V-amylose structure affect the structural and digestive stability of amylose-alkylresorcinols inclusion complexes

Alkylresorcinols (ARs) are a group of bioactive phenolic lipids and mostly concentrated in the bran of whole grains. In this study, the influences of alkyl chain length of ARs and V-amylose structure on the stability of V-amylose-ARs inclusion complexes were characterized. On the one hand, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and in vitro digestion studies of complexes showed that the crystallinity, thermo-stability, and digestion resistance of V-amylose-ARs inclusion complexes increased with increasing alkyl chain length of ARs. On the other hand, V6-amylose-ARs inclusion complexes displayed the strongest thermostability, the highest crystallinity, and the lowest digestibility compared to V7-amylose-ARs inclusion complexes and V8-amylose-ARs inclusion complexes. It could be concluded that both the helical structure of hydrated V6-amylose and ARs with longer alkyl chain stabilized the structure and stability of the inclusion complexes. This work could pave a way to develop bioactive cereal foods with high bioaccessibility of ARs.

Influence of alkyl chain length of imidazolium-based ionic liquid on the crude oil-aqueous solution IFT under different ionic strengths

Due to the unique potentials of ionic liquid (ILs) for interfacial tension (IFT) reduction, a large number of studies concentrated on the applications of these chemicals. In this way, the current study compares the IFT of 1-dodecyl-3-methylimidazolium chloride ([C12mim]Cl) and 1-octadecyl-3-methylimidazolium chloride ([C18mim]Cl) in the presence and absence of NaCl, to investigate the effect of alkyl chain length on the ILs performance. The measured IFTs reveal that, [C18mim]Cl has a higher influence on the IFT reduction in comparison to [C12mim]Cl, in the absence of ions. However, in the presence of NaCl, longer alkyl chain has a destructive effect on the IFT reduction which means the better efficiency of [C12mim]Cl for IFT reduction compared to [C18mim]Cl. According to the findings, the critical micelle concentrations (CMC), the functionality of IFT and the alkyl chain length of imidazolium based ILs depend not only on the number of methyl presented in the cationic part of the IL, but also on the ionic strength of the aqueous solution. The common effect of alkyl chain length (i.e. reduction of surface activity as a function of cation chain length) can be reversed at the presence of the salt, as the surface activity of shorter cation chain length is higher in the presence of NaCl.

Influence of Alkyl Chain Length and Temperature on the Densities, Viscosities and Speeds of Sound of Binary Liquid Mixtures of {2-Methyl-1-Butanol + 2-Ethoxyethanol, or 2-Propoxyethanol, or 2-Butoxyethanol} at T = (298.15, 303.15 and 308.15) K

Influence of Alkyl Chain Length and Temperature on the Densities, Viscosities and Speeds of Sound of Binary Liquid Mixtures of {2-Methyl-1-Butanol + 2-Ethoxyethanol, or 2-Propoxyethanol, or 2-Butoxyethanol} at T = (298.15, 303.15 and 308.15) K

Influence of alkyl chain length of monocationic ionic liquids towards pharmacological activities

In this present work, to synthesis alkyl and aryl substituted monocationic ionic liquids (ILs) of 1–benzyl–3–octadecylimidazolium bromide (ILa), 1–benzyl–3–octadecylbenzimidazolium bromide (ILb), 1–benzyl–3–ethylbenzimidazolium bromide (ILc), 1–benzyl–3–ethylimidazolium bromide (ILd) and 1–benzylpyridinium bromide (ILe), the synthesized ILs are structurally characterized using various physico–chemical, analytical and spectral (FT–IR, 1H & 13C NMR, EI-MS) studies. The synthesized ILs of 1–benzyl–3–ethylbenzimidazolium bromide (ILc), 1–benzyl–3–ethylimidazolium bromide (ILd) and 1–benzylpyridinium bromide (ILe) exhibited significant in vitro biological and antioxidant activities. Furthermore, the synthesized ILs (ILa– ILe) were tested for their in vitro cytotoxicity against human leukemia cancer cell line K–562, human ovarian cancer cell line SK–OV–3, human prostate cancer cell line DU–145 and human non-tumor cell line (normal fetal lung fibroblasts, MRC-5) by SRB assay protocol. The results indicate that 1–benzyl–3–octadecylimidazolium bromide (ILa) and 1–benzyl–3–octadecylbenzimidazolium bromide (ILb) showed remarkable toxicity against cancer cells and low toxicity against healthy cell line. These facts open the possibility of designing new nontoxic ionic liquids that can be used as active pharmaceutical ingredients in the liquid form.

Adsorption of tungstate using cationic gemini surfactant-modified montmorillonite: Influence of alkyl chain length

Influence of alkyl chain length on the adsorption characteristics of organic pollutants by conventional cationic surfactant-modified montmorillonite (Mt) has been well explored. However, applying different cationic gemini surfactants to modify Mt for the adsorption of pollutant that possesses different species in aqueous solution to insightfully understand the structure-property relationship is rarely reported. In this study, three gemini surfactants with different alkyl chain lengths (number of carbon atoms, m = 12, 14, and 18) are selected to regulate the distribution and configuration in the composites. Tungstate, an emerging pollutant, is chosen as a probe, and its different species are modulated by changing the adsorption temperature and pH. The molar contents of the three surfactants are negligibly affected by the alkyl chain length, while the distributions of surfactants in the interlayer space and on the external surface are different. Lengthening the alkyl chain increases the packing density, lowering the accessibility of adsorption sites and decreasing the uptake of tungstates. At lower temperatures and pH values, polytungstates are the predominant species in the solution and are more favorably immobilized by the modified Mt. Ion exchange with Br − ions and desorption-adsorption are jointly responsible for the adsorption of tungstates, and both of these processes are configuration-dependent. The modified Mt by the gemini surfactants with longer alkyl chains demonstrates a lower ion exchange percentage and a more remarkable uptake of tungstates on the external surface. The adsorption of tungstates is accompanied by the rearrangement of gemini surfactants. Thus, elucidating the self-accommodation mechanism of cationic gemini surfactants during tungstates adsorption on modified Mt will provide a significant reference for the design of cationic surfactant- modified clay minerals used for pollutant immobilization. • Gemini surfactant-modified montmorillonite (Mt) was used to remove tungstate. • Gemini surfactant configuration is modulated via changing alkyl chain length. • Lower temperature and pH are beneficial for tungstate uptake on modified Mt. • Polytungstates are more favorably immobilized by the modified Mt. • Tungstate uptake was accompanied with the surfactant self-accommodation.

Ionic liquid-air interface probed by sum frequency generation spectroscopy and molecular dynamics simulation: influence of alkyl chain length and anion volume

ABSTRACT Understand the structure of the ILs/air interface on a molecular level is significant. In this work, the liquid-air interface of a class of ILs containing 1-alkyl-3-methylimidazolium cations ([Cnmim]+, n = 4, 6 and 8) was investigated by a sum-frequency generation vibrational spectroscopy experiment. The length of the alkyl chain of cations and anion type (tetrafluoroborate ([BF4]−), thiocyanate ([SCN]−), dicyanamide ([DCA]−), hexafluorophosphate ([PF6]−)) were varied to determine their intrinsic effects to the micro-structure on the interface. Meanwhile, combining with the experiment, the orientation angle and surface density for cations and anions of ILs at the air interface was analyzed by molecular dynamics simulation. It is found that the butyl side chain of cations protrudes out into the air as well as the orientation angle between the side chain and interface is 30°–50°. Meanwhile, the anion volume of ILs has almost no influence on the butyl side chain and the methyl on the side chains tend almost planar to the interface with the increased chain length. This research is highly significant for the theoretical and quantitative understanding of the interface chemistry of imidazole-based ILs.

Influence of Alkyl Chain Length on Thermal Properties, Structure, and Self-Diffusion Coefficients of Alkyltriethylammonium-Based Ionic Liquids.

The application of ionic liquids (ILs) has grown enormously, from their use as simple solvents, catalysts, media in separation science, or electrolytes to that as task-specific, tunable molecular machines with appropriate properties. A thorough understanding of these properties and structure–property relationships is needed to fully exploit their potential, open new directions in IL-based research and, finally, properly implement the appropriate applications. In this work, we investigated the structure–properties relationships of a series of alkyltriethylammonium bis(trifluoromethanesulfonyl)imide [TEA-R][TFSI] ionic liquids in relation to their thermal behavior, structure organization, and self-diffusion coefficients in the bulk state using DSC, FT-IR, SAXS, and NMR diffusometry techniques. The phase transition temperatures were determined, indicating alkyl chain dependency. Fourier-transformed infrared spectroscopy studies revealed the structuration of the ionic liquids along with alkyl chain elongation. SAXS experiments clearly demonstrated the existence of polar/non-polar domains. The alkyl chain length influenced the expansion of the non-polar domains, leading to the expansion between cation heads in polar regions of the structured IL. 1H NMR self-diffusion coefficients indicated that alkyl chain elongation generally caused the lowering of the self-diffusion coefficients. Moreover, we show that the diffusion of anions and cations of ILs is similar, even though they vary in their size.

Synthesis, X-ray Single-Crystal Structural Characterization, and Thermal Analysis of Bis(O-alkylxanthato)Cd(II) and Bis(O-alkylxanthato)Zn(II) Complexes Used as Precursors for Cadmium and Zinc Sulfide Thin Films.

This work investigates tuning of the molecular structure of a series of O-alkylxanthato zinc and cadmium precursor complexes to enhance production of ZnS and CdS materials. The structures of several bis(O-alkylxanthato) cadmium(II) complexes (8-13) and bis(O-alkyl xanthato)zinc(II) complexes (18 and 19) are reported based on single crystal X-ray diffraction data. CdS and ZnS films were produced by the spin-coating of these metal complexes followed by their thermal decomposition to the corresponding metal sulfides. Thin films of CdS were deposited by spin-coating the bis(O-alkylxanthato) cadmium(II) precursors (7-13) on glass substrates, followed by annealing at 300 °C for 60 min. Thin films of ZnS were deposited by spin-coating bis(O-alkylxanthato) zinc(II) (14-20), followed by annealing at 200 °C for 60 min. The molecular complexes and solid state materials are characterized using a range of techniques including single-crystal X-ray diffraction, pXRD, EDS and XPS, DSC and TGA, UV-vis and PL spectroscopies, and electron microscopy. These techniques provided information on the influence of alkyl chain length on the thermal conditions required to fabricate metal sulfide films as well as film properties such as film quality, and morphology. For example, the obtained crystallite size of metal sulfide films formed is correlated to the hydrocarbon chain length of xanthate ligands in the precursor. The behavior of the complexes under thermal stress was therefore studied in detail. DTA and TGA profiles explain the relationship between hydrocarbon chain length, decomposition temperatures, and the energies required for decomposition. A higher decomposition temperature for complexes with longer hydrocarbon chains is observed compared to complexes with shorter hydrocarbon chains. Band-gap energies calculated from the optical absorption spectra alongside steady state and time-resolved photoluminescence studies are reported for CdS films.

Influence of alkyl chain length on the action of acetylated monoglycerides as plasticizers for poly (vinyl chloride) food packaging film

Acetylated monoglyceride (AMG) is one of the most innoxious and effective external plasticizers for poly (vinyl chloride) (PVC) food packaging film because it is approved as a food additive and its carbonyl group of a carboxylic ester and aliphatic side chain of an ester allow unique interactions with PVC. Monoglyceride moieties can vary because the alkyl chain length is mainly derived from fatty acids of vegetable oils, and AMG enhances the flexibility and elasticity of PVC polymers. To investigate the influence of alkyl chain length, the thermal properties and mechanical performance of AMGs consisting of caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid were studied in a PVC system. The optimum alkyl chain length for an AMG was C14:0, based on data obtained from stress at break, strain at break, Young’s modulus, glass transition temperature, thermal degradation, and migration rate tests.

Effect of Alkyl Chain Length on Charge Transport Property of Anthracene-Based Organic Semiconductors.

Anthracene, a simple planar building block for organic semiconductors, shows strong intermolecular interactions and exhibits strong blue fluorescence. Thus, its derivatives have a great potential to integrate considerable charge carrier mobility and strong emission within a molecule. Here, we systematically studied the influence of alkyl chain length on the crystal structures, thermal properties, photophysical characteristics, electrochemical behaviors, and mobilities for a series of 2,6-di(4-alkyl-phenyl)anthracenes (Cn-Ph-Ants, where n represents the alkyl chain length). Among them, Cn-Ph-Ants (n = 0, 1, 2, and 3) display similar layered herringbone (LHB) packing motifs, which facilitate two-dimensional charge transport and thereby enables high-performance organic field-effect transistors (OFETs). All Cn-Ph-Ants exhibit similar work functions and show strong blue fluorescence with photoluminescence quantum yields (PLQY) of approximately 40% in toluene. In addition, the absolute powder PLQYs of C0-, C2-, C3-, C4-, and C6-Ph-Ants are 24.6, 8.2, 5.7, 10.9, and 8.6%, respectively. Note that the alkyl chain length shows a significant effect on the charge mobilities of Cn-Ph-Ants. Our newly synthesized C1-, C3-, and C4-Ph-Ants show hole mobilities of up to 2.40, 1.34, and 1.00 cm2 V-1 s-1, respectively, with mobilities of 3.40, 1.57, and 0.82 cm2 V-1 s-1 for C0-, C2-, and C6-Ph-Ants, indicating an increasing tendency of mobility with shorter alkyl chain length. This feature is related to the microstructures of the thin films, which reveal the enhanced film order, crystallinity, and grain size with a decrease in the alkyl chain length. Moreover, we theoretically analyze the intermolecular transfer integrals of HOMOs, which increase at T-shaped contacts as the alkyl chain length decreases, which improves the intermolecular charge transport properties, leading to the increases in mobility. Interestingly, the anisotropy of the transfer integral tends to decrease upon substitution with longer alkyl chains, suggesting that alkyl chain adjustments may facilitate isotropic charge transport property in 2,6-alkylated anthracenes.