Molecular Interaction Parameters Research Articles

Mixed Micelles of Binary Mixtures of Sodium Dodecylbenzene Sulfate and Tween 80 Surfactants in Aqueous Solutions

In the present work, the surface properties of mixed binary surfactants containing sodium dodecylbenzene sulfate (SDBS) and Tween 80 (TW80) surfactants in aqueous solutions were studied at temperature 293 K using surface tension measurements. The critical micelle concentration (cmc) magnitude for both individual surfactants and their mixtures were established the obtained results revealed that the magnitude of cmc of the mixtures are less than the magnitude of individual surfactants and decrease with the increase in Tween 80 percent in solution which indicate the nonideal mixing of the two surfactants. The values of molecular interaction parameters and the mole fraction of surfactants in the micelle (X1) were calculated on the basis of Rubingh’s model and showed that the interaction parameter is always negative but at 0.9 mole fraction of TW80 surfactant (α1) is positive

3,4‐Dicyanothiophene—a Versatile Building Block for Efficient Nonfullerene Polymer Solar Cells

AbstractIn this contribution, a versatile building block, 3,4‐dicyanothiophene (DCT), which possesses structural simplicity and synthetic accessibility for constructing high‐performance, low‐cost, wide‐bandgap conjugated polymers for use as donors in polymer solar cells (PSCs), is reported. A prototype polymer, PB3TCN‐C66, and its cyano‐free analogue polymer PB3T‐C66, are synthesized to evaluate the potential of using DCT in nonfullerene PSCs. A stronger aggregation property in solution, higher thermal transition temperatures with higher enthalpies, a larger dipole moment, higher relative dielectric constant, and more linear conformation are exhibited by PB3TCN‐C66. Solar cells employing IT‐4F as the electron acceptor offer power conversion efficiencies (PCEs) of 11.2% and 2.3% for PB3TCN‐C66 and PB3T‐C66, respectively. Morphological characterizations reveal that the PB3TCN‐C66:IT‐4F blend exhibits better π–π paracrystallinity, a contracted domain size, and higher phase purity, consistent with its higher molecular interaction parameter, derived from thermodynamic calculations. Moreover, PB3TCN‐C66 offers a higher open‐circuit voltage and reduced energy loss than most state‐of‐the‐art wide‐bandgap polymers, without the need of additional electron‐withdrawing substituents. Two additional polymers derived from DCT also demonstrate promising performance with a higher PCE of 13.4% being achieved. Thus, DCT represents a versatile and promising building block for constructing high‐performance, low‐cost, conjugated polymers for application in PSCs.

Interfacial Interaction of Binary Mixtures of Surfactants Hexadecyl Benzylammonium Chloride (HDBAC) and Tween 20 in Aqueous Solutions

The surface adsorption properties of mixed binary surfactants containing hexadecyl benzylammonium chloride (HDBAC) and Tween 20 in aqueous solutions were studied at different temperatures (288-318K) using tensiometry techniques. The interaction parameters and surface activity for both individual and mixed surfactants systems, the Critical Micelle Concentration (CMC), maximum surface excess concentration (Γmax) and minimum surface area per surfactant molecule (Amin) at the air-water interface were determined. Also, the parameters related to synergism in surface activity such as adsorption efficiency (pC20) and CMC/C20 were calculated. The results obtained reveal that the binary mixed system possess CMC values lower than its components and these values decrease with increasing the concentration of Tween 20 in the solution. This behavior shows non-ideal synergism of the mixing process. The values of molecular interaction parameters βσ and the mole fraction of components at the air-water interface X1σ are calculated on the basis of Rosen's model and showed that the interaction parameter of the adsorbed monolayer is always negative and has a higher negative value for 0.9 Tween mole fractions.

MOLECULAR INTERACTION PARAMETERS THROUGH FTIR SPECTRAL ANALYSIS

Ponte Academic JournalNov 2020, Volume 76, Issue 11 MOLECULAR INTERACTION PARAMETERS THROUGH FTIR SPECTRAL ANALYSISAuthor(s): K. Srisanthi ,Sk. Suriya Shihab, K. Mallika, S. Sreehari SastrymJ. Ponte - Nov 2020 - Volume 76 - Issue 11 doi: 10.21506/j.ponte.2020.11.11 Abstract:Molecular interaction parameters and the strength of molecular interactions in the binary mixtures of Propylene glycol and Heptanol for different molar ratios are investigated through FTIR spectral data analysis. The intermolecular interaction parameters: Force constant, bond length, infrared intensity enhancement and molecular polarizability are considered in the computation. These parameters are very sensitive to the shifts in the vibrational frequencies that are caused by molecular interactions of functional groups. Propylene glycol (PG) and Heptanol for different molar ratios (PG + Heptanol: 0.1 + 0.9 to 0.9 + 0.1) that are taken for determining hydrogen bonded liquid complex systems. The results confirmed showing that the intermolecular hydrogen bond formation for molar ratio of the liquid complex 0.2 + 0.8 is stronger compared to other molar systems. Further, the observed results are correlated by the statistical analysis of FTIR data. Such statistical analysis includes the computation of variance � covariance values and eigen values using MATALAB computational tool. Download full text:Check if you have access through your login credentials or your institution Username Password

Evaluation of Ultrasonic Velocity Theories on Binary Liquid Mixtures of Propiophenone with Isomeric Xylenes at Temperatures (T = 303.15 to 318.15 K)

Densities (ρ), ultrasonic speeds of sound (u) of binary mixtures containing propiophenone with o-xylene, m-xylene and p-xylene were measured over the entire composition range at temperatures from 303.15-318.15 K and at atmospheric pressure 0.1 MPa. Experimental data of ultrasonic velocity was used to compute the theoretical velocities by using the various theories like Nomoto’s relation (UNOM), impedance relation (UIMP), Van Dael and Vangeel’s relation (UVDV), Rao’s specific velocity relation (URAO), Jouyban-Acree’s (UJOE) and Junjie’s theory (UJUN). The results are in good agreement with the experimental data. The relative percentage error, chi square test for goodness of fit and the molecular interaction parameter (α) values for non-ideality in the binary mixtures were computed and analyzed in terms of intermolecular interactions between the molecules of the binary mixtures.

Molecular Interactions from the Experimental and Validation with Estimated Theoretical Sound Velocity

The ultrasonic velocity, density and viscosity measurements carried out for the binary mixtures of toluene, m-xylene with some butanols at 303 K. Various theoretical models have been applied to these binary systems; evaluate the sound velocity values and compared with the experimental values. The validity of Nomoto theory (NT), Van Deal-Vangeal (IMR) and Free length theory (FLT) is checked and a comparative study of the above models is made. The non-ideal behavior of the system is explained in terms of molecular interactions of the constituents of the mixture. The interactions further, evident with percentage deviation, molecular interaction parameter and goodness fit test.

Molecular Interactions in Binary Surfactant Solutions: Effect of pH

By using surface tension and conductivity measurements, the colloid-chemical properties of the mixtures of cationic hexadecylpyridinium bromide with nonionic Triton X-100 surfactants were investigated both in the bulk solution and at air/solution interface at different pH values. The composition of mixed micelles and adsorption layers, parameters of molecular interactions in mixed micelles βm and adsorption layers βσ, as well as standard free energies of micelle formation ΔG0mic and adsorption ΔG0ads were calculated. It was found that molecules of the nonionic surfactant presumably dominate in the mixed micelles and adsorption layers. It was shown that βm and βσ have negative values, which indicate the strengthening of intermolecular interactions in the mixed micelles and adsorption layers. Based on the data obtained, it was suggested that ion-dipole interactions are involved in the formation of intermolecular structures between nonionic and cationic surfactants in aqueous solution and at the air-solution interface. It was shown that βm, βσ as well as ΔG0mic and ΔG0ads parameter depends on the solution pH value. The complex interplay of ion-dipole, protonation and chelation processes, which occur in the surfactant mixtures at different pH and affect the strength of intermolecular interaction, should be taken into account for data analysis.

Fourier-transform spectroscopy of the A2Πi − X2Σ+ system in CO+ and deperturbation analysis of the A2Πi(v = 0, 1) levels

The A2Πi state of 12C16O+ has been reinvestigated using high-resolution, emission spectra obtained via Fourier-transform spectroscopy of the (0, 1), (0, 2), (1, 0) and (1, 1) bands of the Comet–Tail (A2Πi − X2Σ+) system with accuracy of up to 0.005 cm−1. The high temperature (900 K) of the emission discharge inside the hollow-cathode lamp permitted monitoring of high rotational quantum levels in A2Πi(v = 0, 1) up to J = 48.5. All these bands together with the X2Σ+ − X2Σ+(10, 1) and (10, 2) transitions deriving from a complex, spin-orbit, spin-electronic and L-uncoupling A2Π(v = 0) ∼ X2Σ+(v = 10) interaction as well as the B2Σ+ − X2Σ+(6, 10) frequency transitions from our previous study were taken into consideration. In total, 1849 spectral lines were included in the comprehensive deperturbation analysis. This fit leads to a much improved description in terms of deperturbed molecular constants and interaction parameters compared to the previous studies of the same energy region in CO+. Moreover, the ro-vibronic term values of the A2Πi(v = 0) level and its perturber X2Σ+(v = 10) were determined as well as Λ-doubling of A2Πi(v = 0,1), γ-doubling of X2Σ+(v = 10) and percentage 2Π character of these levels were considered in detail.

Molecular Interaction Studies in Ternary Liquid Mixtures Containing 2-Nitroanisole and 1- Pentanol in n- Hexane at Different Temperatures using Ultrasonic Techniques

The experimental values of ultrasonic velocity, density and viscosity have been measured for the ternary liquid mixtures containing 2-Nitroanisole and 1-Pentanol in n-Hexane at 303,308 and 313K. To calculate various acoustical parameters like adiabatic compressibility, free volume, internal pressure, acoustical impedance, adsorption co-efficient and molecular interaction parameters have been computed using the experimental data. The linearity of variation in ultrasonic velocity and other parameters are due to the molecular interaction between donor acceptor molecules in liquid-liquid mixture. The various molecular interactions like dipole-dipole, dipole-induced dipole, induced-induced dipole have been discussed for the liquid mixture containing 2-Nitroanisone, 1-Pentanol in n-Hexane at different temperatures and concentration.

Gas Adsorption and Interfacial Tension with Classical Density Functional Theory

A classical density functional theory (DFT) that reduces to the perturbed chain statistical associating fluid theory equation of state has been implemented. This DFT implementation allows the use of molecular and binary interaction parameters fitted to the vapor–liquid equilibria of pure compounds and binary mixtures, respectively. Different functionals of dispersion forces are investigated and applied to the calculation of interfacial tension and adsorption of pure gases and their mixtures. The predictions of interfacial tension have been compared with both molecular simulations and experimental data, and good agreements have been seen. The DFT approaches also show good performance in correlating and predicting gas adsorption, and they are further compared with the multicomponent potential theory of adsorption and other DFT approaches available in the literature.

A tribological application of the coarse-grained molecular dynamics simulation and its experimental verification

Abstract We developed a method to simulate the polytetrafluoroethylene (PTFE) tribology by estimating the molecular interaction parameters on the basis of experimental verification. We fitted the molecular interaction parameters between coarse-grained PTFE beads using the iterative Boltzmann inversion method and multi-centered Gaussian-based potentials. The fitting parameters were subsequently validated by comparing an all-atom PTFE model and its corresponding coarse-grained model. A two-layer PTFE friction model was then built on the basis of the estimated parameters to study the effect of normal load on the friction coefficient and wear depth of PTFE. The simulation results showed that the friction coefficient decreases and the wear depth increases as the normal load increases. Moreover, the reasonability of the simulation results was verified through experiments.

Interaction of Bile Salts with Cetylpyridinium Chloride: Surface Tension and Viscosity Measurements

Background: Bile salts possess unique chemical structural characteristics and are very different from conventional surfactants. Due to the fascinating physiological functions, the bile salts have been widely studied by various physical methods. Last three decades are the witness about rapid studies on bile salts aggregation with surfactant but yet uncertain related to mixed micellar system. Objective: The primary objective of this study was to undertake systematic studies on the mixed systems comprising of cationic surfactant CPyCl + bile salts in water and NaCl solution by surface tension and viscosity method. Methods: Drop weight method (surface tension method) and viscometry methods are chosen to discuss the interaction between bile salts and surfactant mixed system. Results: Systematic studies on CPyCl + bile salts were carried out using Rubingh’s regular solution theory in presence/absence of NaCl. The CMC and viscosity data measurements were recorded. Molecular interaction parameters β was calculated to determine the depth of synergism between the micellar systems. Conclusions: Synergisms occur when cationic surfactant CPyCl and bile salts such as NaDC/NaC were mixed. NaCl has the ability to modify the structure of CPyCl and bile salts. Micelle size grows with increase in NaCl concentration. CMC of CPyCl decreases as the concentration of salts increases. Viscosity data reveals that size of CPyCl micelle increases with increasing NaCl concentration. Keywords: Bile salt, micellization, surfactant, CMC, hydrographic, aliphatic.

Precision spectroscopy and comprehensive analysis of perturbations in the A1∏(v = 0) state of 13C18O

ABSTRACTWe have reinvestigated the A level of 13C18O using new high-resolution spectra obtained via multi-photon laser excitation as well as with synchrotron-based Fourier-transform absorption spectroscopy of the A, e, d, a, and a bands. In addition, Fourier-transform emission spectroscopy in the visible range is performed on the band. Spectra of the B band are measured in order to tie information from the latter emission data to the level structure of A. The high pressures in the absorption cell at the synchrotron and the high temperatures in the emission discharge permitted monitoring of high rotational quantum levels in A up to J=43. All information, in total over 900 spectral lines, was included in an effective Hamiltonian analysis of the Alevels that are directly perturbed by the e, d, a, D, I close-lying levels and the e, d, a remote levels, as well being indirectly influenced by the a state. The influence of 9 further perturber levels and their interactions was investigated and are not significant for reproducing the present experimental data. This analysis leads to a much improved description in terms of molecular constants and interaction parameters, compared to previous studies of the same energy region for other CO isotopologues.

The ultra-low interfacial tension behavior of the combined cationic/anionic-nonionic gemini surfactants system for chemical flooding

Gemini surfactants have attracted intensive attention owning to their unique physical and chemical properties and have gradually been applied in the field of enhanced oil recovery (EOR). In this work, a combined cationic/anionic-nonionic gemini surfactant system consisting of cetyltrimethyl ammonium bromide (CTAB) and anionic-nonionic gemini surfactants (GAES-9) was proposed for EOR. The surface performance of the combined system was superior to that of either surfactant alone. Critical micelle concentration (CMC) data were used to calculate the molecular interaction parameters according to the regular solution theory. The combined CTAB/GAES-9 surfactant system could greatly affect the interfacial tension (IFT) between water and crude oil, and the strength of this effect depended on the mole fraction and concentration of CTAB/GAES-9. The system could reduce the IFT to an ultra-low level at a total concentration of 200 mg/L, and the system could still maintain ultra-low IFT at a salinity of 10 × 104 mg/L. The mechanism underlying the synergistic effect of CTAB/GAES-9 to obtain ultra-low IFT was systematically investigated. It is most probably related to a large number of anions and cations being adsorbed onto the oil-water interface due to electrostatic attraction. Meanwhile, the spatial structure of the elongated, flexible EO chains in the gemini surfactant entangled at the oil-water interface shields some CTAB cations, enabling the adsorption of more cations. To summarize, the combined surfactants exhibit remarkable abilities and could serve as a candidate for EOR in harsh reservoirs.

Molecular Interaction and Excess Thermodynamic Parameters In Binary Liquid Mixture Through Ultrasonic Measurements at 313.15 K

Molecular Interaction and Excess Thermodynamic Parameters In Binary Liquid Mixture Through Ultrasonic Measurements at 313.15 K

Ultrasonic study on binary liquid mixtures of propiophenone with anilines and alkyl substituted anilines at T=303.15 to 318.15 K

Densities ‘ρ’, ultrasonic speeds of sound ‘u’ of binary mixtures of propiophenone (PPH) with aniline, N-Methylaniline, N,N-dimethylaniline and N,N-diethylaniline were measured over the entire composition range from 303.15 K to 318.15 K and at atmospheric pressure 0.1 MPa. Experimental data of ultrasonic sound were compared and discussed with the computed values of ‘u’ from various velocity theories like Nomoto’s relation (UNOM), impedance relation (UIMP), Van Dael and Vangeel’s ideal mix relation (UVDV), Rao’s specific velocity relation (URAO), Junjie’s theory (UJUN) and Jouyban-Acree’s (UJOE) relation for the above binary mixtures over the entire mole fraction range at the studied temperatures. The results are satisfactory and are in agreement between the theoretical and the experimental values. Further, the molecular interaction parameter (α), average percentage error and Chi-square test values were computed by using the values of experimental and theoretical ultrasonic velocities. The Δu values were correlated with Redlich-Kister polynomial equation to compute the coefficients and the standard deviations of the binary mixtures. The results were analyzed in terms of intermolecular interactions.

Compressible flow at high pressure with linear equation of state

Compressible flow varies from ideal-gas behaviour at high pressures where molecular interactions become important. It is widely accepted that density is well described through a cubic equation of state while enthalpy and sound speed are functions of both temperature and pressure, based on two parameters, $A$ and $B$, related to intermolecular attraction and repulsion, respectively. Assuming small variations from ideal-gas behaviour, a closed-form approximate solution is obtained that is valid over a wide range of conditions. An expansion in these molecular interaction parameters simplifies relations for flow variables, elucidating the role of molecular repulsion and attraction in variations from ideal-gas behaviour. Real-gas modifications in density, enthalpy and sound speed for a given pressure and temperature lead to variations in many basic compressible-flow configurations. Sometimes, the variations can be substantial in quantitative or qualitative terms. The new approach is applied to choked-nozzle flow, isentropic flow, nonlinear wave propagation and flow across a shock wave, all for a real gas. Modifications are obtained for allowable mass flow through a choked nozzle, nozzle thrust, sonic wave speed, Riemann invariants, Prandtl’s shock relation and the Rankine–Hugoniot relations. Forced acoustic oscillations can show substantial augmentation of pressure amplitudes when real-gas effects are taken into account. Shocks at higher temperatures and pressures can have larger pressure jumps with real-gas effects. Weak shocks decay to zero strength at sonic speed. The proposed framework can rely on any cubic equation of state and can be applied to multicomponent flows or to more complex flow configurations.

Theoretical assessment of ultrasonic velocities of binary liquid mixtures containing p-chloroacetophenone with 1-alcohols at temperatures from 303.15 K to 318.15 K

Ultrasonic velocities and densities and viscosities of parachloroacetophenone with alcohols have been measured at temperatures range from 303.15 K to 318.15 K over the entire composition range of mole fraction. Theoretical ultrasonic velocities were correlated by using Nomoto's relation (UNOM), Impedance relation (UIR), Ideal mixing relation (UIMR), Junjie's relation (UJ) and Rao's specific velocity (UR). The theoretical and experimental values found good agreement with molecular interaction parameter (α) and chi square Goodness-of-fit test (Χ2).

Thermodynamic Characterization of Temperature‐ and Composition‐Dependent Mixed Micelle Formation in Aqueous Medium

AbstractThis article provides a detailed description of micellization of a binary nonionic surfactant system (Lutensol AP9 and AP20) at different compositions and temperatures in an aqueous medium. Critical micelle concentrations of the individual components (CMCi) and the mixed surfactants (CMCm) were determined via surface tension measurements in the temperature range of 288.15–318.15 K. On the basis of the magnitude and temperature dependence of CMC values, changes in the Gibbs energy (ΔmicG), enthalpy (ΔmicH), and entropy (ΔmicS) of micellization were evaluated. At 288.15 K the thermodynamic parameters were confirmed by isotherm titration calorimetry (ITC). Regular solution theory (RST) was used to estimate the compositions of the mixed micelles (XM) and molecular interaction parameters (βM) for all molar ratios and temperatures. The results of evaluations based on the closed association model and RST were compared.

Phase behavior of Carbon dioxide/Trimethoxy(methyl)silane and Methylsilicate 51 system

The phase behaviors of carbon dioxide (CO2)/trimethoxy(methyl)silane (MTMS) and CO2/Methylsilicate 51 (MS-51: methylsilicate tetramer) binary systems were determined. The experiments were performed using a synthetic method by observing the bubble point. The phase boundaries were determined at temperatures of 313.2 K–393.2 K and CO2 molar fractions of 0.2–0.9. The experimentally obtained bubble points of the CO2/MTMS binary system were correlated using the Peng-Robinson equation of state (PR EoS), and the molecular interaction parameters kij and lij were determined. The results of the CO2/MS-51 binary system were correlated using the PR EoS and the Sanchez-Lacombe equation of state (SL EoS). In the SL EoS, two types of mixing rules, originally proposed by Sanchez et al. which uses kij as a fitting parameter and modified by McHugh et al. which uses two fitting parameters kij and lij, were used. For this system, the experimental results were correlated better using the SL EoS than using the PR EoS, and the latter mixing rule was more suitable than the former.