Net Retention Volumes Research Articles

Effect of Tacticity on London Dispersive Surface Energy, Polar Free Energy and Lewis Acid-Base Surface Energies of Poly Methyl Methacrylate by Inverse Gas Chromatography

This research was devoted to study the effect of the tacticity on the surface physicochemical properties of PMMA. (1) Background: The determination of the surface free energy of polymers is generally carried out by inverse gas chromatography (IGC) at infinite dilution. The dispersive, polar and surface acid-base properties of PMMA at different tacticities were obtained via IGC technique with the help of the net retention time and volume of adsorbed. (2) Methods: The London dispersion equation was used to quantify the polar free energy of adsorption, while the London dispersive surface energy γsd(T) of PMMAs was determined using the thermal model. (3) Results: The results showed non-linear variations of γsd(T) of atactic, isotactic, and syndiotactic PMMAs with three maxima characterizing the three transition temperatures of PMMAs. The obtained values of the enthalpic and entropic Lewis’s acid-base parameters showed that the basicity of the atactic PMMA was about four times larger than its acidity. (4) Conclusions: A large difference in the behavior of the various PMMAs was proven in the different values of the polar acid and base surface energies of the three PMMAs with an important effect of the tacticity of PMMA on its acid-base surface energies.

Investigation of Physicochemical Characteristics of Aspergillus niger Biomass and Examination of Its Ability to Separate Butyl Acetate Isomers.

Aspergillus niger is a species of fungus that is widely found in natural ecosystems and has an important role in various industrial fields and is readily available. To study the adhesion of microbial cells to solid substrates and to improve their properties, physicochemical characterization of microorganisms is extremely important. For this purpose, in this study, the surface properties of A. niger biomass were determined at low cost and with high accuracy by inverse gas chromatography (IGC), a physicochemical characterization technique. IGC experiments were conducted between 303.2 and 328.2K at infinite dilution. Among these temperatures, various organic solvent vapors were passed over the A. niger biomass considered as stationary phase and their retention behavior was studied. Using the raw data, net retention volumes were calculated and retention diagrams were drawn. From the linear retention diagrams, the dispersive surface energy was calculated according to Dorris-Gray (48.73-46.09 mJ/m2), Donnet-Park (47.12-44.50 mJ/m2), Schultz (46.88-42.45 mJ/m2), and Hamieh (76.42-64.06 mJ/m2) methods. With the IGC method, the acidity-basicity parameters of A. niger biomass were determined and it was found that the surface was basic ( ). In the second part of this study, the butyl acetate isomer series, which are difficult to be separated by conventional methods, were effectively separated by the IGC method using A. niger stationary phase.

New Progress on London Dispersive Energy, Polar Surface Interactions, and Lewis's Acid-Base Properties of Solid Surfaces.

The determination of the polar surface free energy, polar properties, and Lewis's acid base of solid materials is of capital importance in many industrial processes, such as adhesion, coatings, two-dimensional films, and adsorption phenomena. (1) Background: The physicochemical properties of many solid particles were characterized during the last forty years by using the retention time of injected well-known molecules into chromatographic columns containing the solid substrates to be characterized. The obtained net retention time of the solvents adsorbed on the solid, allowing the determination of the net retention volume directly correlated to the specific surface variables, dispersive, polar, and acid-base properties. (2) Methods: Many chromatographic methods were used to quantify the values of the different specific surface variables of the solids. However, one found a large deviation between the different results. In this paper, one proposed a new method based on the London dispersion equation that allowed the quantification of the polar free energy of adsorption, as well as the Lewis's acid-base constants of many solid surfaces. (3) Results: The newly applied method allowed us to obtain the polar enthalpy and entropy of adsorption of polar model organic molecules on several solid substrates, such as silica, alumina, MgO, ZnO, Zn, TiO2, and carbon fibers. (4) Conclusions: our new method based on the separation between the dispersive and polar free surface energy allowed us to better characterize the solid materials.

Thermal modeling for anionic surfactant using Inverse gas chromatography and image processing techniques

Anionic surfactants are one of the necessary ingredients demanded in extensive bio-and pharmaceutical industry. Their concern on human health and environmental safety get increase and is originated from its surface thermodynamic properties. Surface thermodynamic properties have severely an effect on thermodynamic and kinetic parameters in the chemical reaction. However, there is a kind of serious differences between theoretical calculation and experimental result because of lacks of understanding on complex surface thermodynamic properties. Inverse gas chromatography (IGC) is an analytic chemistry tool providing information on physicochemical and thermodynamic parameters. Herein, a thermal modeling of surface thermodynamic properties is suggested. Net retention volume, VN, of n-alkanes and polar probes upon sodium lauryl sulfate surface properties as an anionic surfactant are analyzed at diverse temperatures range from 363.15 to 433.15 K using IGC. VN of n-alkane values are employed to assess the London dispersive surface free energy, γSL by comprehensive thermodynamic models and results into the Guttmann Lewis acid-base parameters and acid-base constants. The results reveal that an excellent linear correlation coefficient value closer to 1. The current work demonstrates how to approach surface thermodynamic characteristics of anionic surfactant and suggests a new thermal model as an advanced model. Additionally, scanning electron microscopy image analysis regarding the surface morphology has been carried out using image processing techniques. Current comprehensive approach enables to analyze and apply for an effective understanding on surfactant molecules.

Surface thermodynamic properties of sodium carboxymethyl cellulose by inverse gas chromatography

This study constitutes a new development of surface thermodynamic methods to determine the London dispersive surface free energy component γsd, the specific free energy of adsorption and the Lewis acid-base properties of polymers by using inverse gas chromatography (IGC) at infinite dilution. The net retention volumes Vn of n-alkanes and polar solvents adsorbed on a sodium carboxymethyl cellulose (Na-CMC) polymer surface were determined at four temperatures 313.15K, 323.15K, 333.15 and -343.15K by IGC technique The London dispersive surface free energy component of Na-CMC was determined by using Dorris-Gray and Dorris-Gray-Hamieh methods, Van der Waals, Redlich-Kwong, Kiselev, geometric, cylindrical, spherical and Hamieh models. The more accurate value of γsd of Na-CMC was obtained by Hamieh model taking into account the thermal effect on the surface areas of molecules: γsd(T)(mJ/m2)=−0.630T(K)+229.01 showing a maximal temperature TMax = 91°C that can be considered as a new characteristic of the Na-CMC polymer. Above TMax, there is no dispersive component of the surface energy of the polymer surface.The specific interactions of Na-CMC particles were determined by using the various molecular models, and the vapor pressure, the boiling point, the topological index and the deformation polarization IGC methods. The obtained results clearly showed a strong Lewis basicity of Na-CMC (about seven times more basic than acidic polymer surface). It was proved that the IGC methods and models do not give similar results. The thermal model gave the most accurate result of the Lewis acid-base properties of Na-CMC surface.

Evaluation of the surface properties of 4-(Decyloxy) benzoic acid liquid crystal and its use in structural isomer separation.

The selectivity of 4-(Decyloxy) benzoic acid (DBA) liquid crystal in surface adsorption region (303.2–328.2 K) and thermodynamic region (423.2 – 433.2 K) was investigated by inverse gas chromatography at infinite dilution (IGC-ID). The selectivity parameters of the structural isomer series named butyl acetate, butyl alcohol, and amyl alcohol series were calculated for the DBA using IGC-ID technique. Additionally, the surface properties including dispersive surface energy (gS D), free energy (DGA S), enthalpy (DHA S), and acidity-basicity constants were calculated with net retention volumes obtained from IGC-ID experiment results. When the DHA S and DGA S are constants, DBA surface was found to be an acidic character (KD/KA @ 0.89).

New Methods for the Determination of the Surface Physicochemical Properties and Glass Transition of Polyaniline in Conducting and Non-Conducting Forms by Using Igc Technique at Infinite Dilution

Many studies were devoted in our Laboratory to the determination of physico-chemical and thermodynamic properties of polymers and/or oxides by using the inverse gas chromatography (IGC) at infinite dilution. More particularly, we studied the interactions of solid substrates with some model organic molecules and their acid-base properties, in Lewis terms, by determining the acidic and basic constants. We proposed in this paper to study the surface thermodynamic energetics, transition phenomena, specific interactions and acid-base properties of both the conducting polyaniline (PANI-HEBSA) and the non-conducting form (PANI-EB) on the light of the new progresses of IGC methods. This technique was used to obtain the net retention volume Vn and then the dispersive free enthalpy of n-alkanes adsorbed on PANI. The curves of the dispersive component of the surface energy of n-alkanes adsorbed on PANI, as a function of the temperature highlighted the presence of two transition temperatures on 383K and 430K respectively for PANI-HEBSA and PANI-EB. There results were confirmed by the curves of RTlnVn =f(1/T) of n-alkanes. The determination of the specific free enthalpy of polar molecules adsorbed on PANI proved a shift of 4K in the value of the glass transition of PANI-EB. From the variation of as a function of the temperature, one deduced the values of the specific enthalpy of the various polar molecules and determined the acidic constant KA and basic constant KD, the two constants characterizing the solid substrate. It was showed that PANI is highly more basic than acidic (about 2.6 times more basic) and an increase of the acid-base character was highlighted near the glass transition for PANI-EB.

Evaluation of the surface properties of poly(ionic liquid) materials by inverse gas chromatography

Inverse gas chromatography (IGC) was used as a tool to evaluate the surface parameters of three poly(1-alkyl-3-vinylimidazolium hexafluorophosphate) (P[CnVIM][PF6], n = 2, 4, 6) materials that were obtained by a free-radical polymerization. IGC characterization was carried out at temperatures ranging between 303.15 and 343.15 K for determining the dispersive free energy (γsd) as well as the Lewis acidity and basicity parameters of the three materials. The retention behaviour of the probes on the surfaces of the three materials was analysed by plotting the net retention volumes (Vn) of the probes as a function of temperature. The dispersive free energy results revealed that all three materials have high γsd values and that the γsd value decreases in an almost linear fashion with increasing temperature. The acid-base data for the three materials confirmed that the surfaces of all three materials can be considered to be amphoteric with a predominantly basic character and that the basicity decreases with increasing alkyl side chain length on the imidazolium backbone.

Surface properties of ionic liquids: A study of different calculation methods in inverse gas chromatography

The surface properties of 1-alkyl-3-vinylimidazolium hexafluorophosphate ([CnVIM][PF6], n = 2,4,6,8) ionic liquids and 1-allyl-3-vinylimidazolium ([AVIM]+), ionic-based liquids with different anions (Cl−, Br−, [BF4]−, [Tf2N]−) were investigated at temperatures between 303.15 and 343.15 K on the basis of inverse gas chromatography (IGC). The Schultz method and Dorris-Gray methods were used to estimate the dispersive free energy based on the net retention volumes of homogeneous n-alkanes, and it was found that the discrepancy between the two methods increases with increasing temperature, with the Dorris-Gray method providing slightly higher values than the Schultz method at the same test temperature. The Lewis acid-base parameters, KA and KB, were likewise assessed by the method proposed by Schultz, Flour and Papirer, Brookman and Sawyer, respectively. Although the difference between the values of acid-base parameters were observed, the ratios of KB/KA obtained by three methods presented the same tendency and implied that the surface of all the tested ionic liquids exhibited the Lewis amphoteric and stronger basic character. In addition, the values of the enthalpies of adsorption between the probes and ionic liquids were also determined.

Surface characterization and London dispersive surface free energy of functionalized single‐walled carbon nanotubes with a blend of polytetrafluoroethylene by inverse gas chromatography

The SWCNTs and SWCNT‐polytetrafluoroethylene (PTFE) blend were prepared by using simple reaction mixture in the presence of chromosorb (SiO2). Surface morphology of SWCNTs and (SWCNT‐PTFE) blend was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and surface BET analysis. In addition, the surface thermodynamic properties of n‐alkanes and polar probe net retention volumes are measured by inverse gas chromatography (IGC). The London dispersive surface free energy values were found to be decreased linearly with increase of temperature. The specific component of the surface free energy of adsorption for the polar probes was obtained using the Donnet‐Park method. The surface character “S” value (Kb/Ka) at SWCNTs was found to be 0.74, and SWCNT‐PTFE blend surface character value was found to be 0.86. This result demonstrates that the (SWCNT‐PTFE) blend surface contains relatively more acidic sites then that of SWCNT surface. Therefore, the IGC results provide useful complementary information on the (SWCNT‐PTFE) blend surface.

Determination of Activity Coefficients at Infinite Dilution of Solutes in N,N′-Di(2-ethylhexyl)isobutyramide Using Inverse Gas–Liquid Chromatography

Activity coefficients at infinite dilution for 30 solutes (alkanes, alkenes, alkyl benzenes, ketones, chloromethanes, aromatic compounds, acetonitrile, formaldehyde, and ethyl acetate) in N,N′-di(2-ethylhexyl)isobutyramide have been determined at temperatures T = (323.15 to 373.15) K by inverse gas chromatographic technique. Net retention volumes of solutes have been measured as a function of temperature. From the temperature dependence of the activity coefficients at infinite dilution, partial molar excess enthalpies and activity coefficients at infinite dilution at 298.15 K of solutes in N,N′-di(2-ethylhexyl)isobutyramide have been derived. Selectivity values at infinite dilution have been computed from the activity coefficients at infinite dilution values.

Determination of surface properties and Gutmann’s Lewis acidity–basicity parameters of thiourea and melamine polymerized graphitic carbon nitride sheets by inverse gas chromatography

Melamine and thiourea-derived graphitic carbon nitrides (M-GCN/T-GCN) were synthesized and characterized. The surface properties were investigated using inverse gas chromatography (IGC) and compared. Net retention volumes of M-GCN and T-GCN were measured with n-alkanes (C5–C10) and polar probes. The London dispersive surface free energies (γsd), calculated using Schultz and Dorris–Gray methods, decreased linearly with increasing temperature. The specific components of the enthalpy and entropy of adsorption for the polar probes were obtained using the Schultz, Dong, and Sawyer–Brookman methods. The Gutmann’s Lewis acid–base parameters, Ka and Kb, were determined using the surface free energy (ΔGaS) via these methods. The surface character ‘S’ values (Kb/Ka) of M-GCN and T-GCN using the respective methods are 4.04, 3.78, and 5.08 and 4.11, 5.27, and 2.86. Hence, the surfaces contain more basic than acidic sites and could interact strongly with acidic media. Thus, IGC elucidates the surface charges of the GCN matrix resulting from surface chemical modification.

Inverse Gas Chromatography Study on London Dispersive Surface Free Energy and Electron Acceptor–Donor of Fluconazole Drug

The inverse gas chromatography study on the fluconazole drug surface was performed, and the net retention volumes, polar probes, and VN of n-alkanes are determined at four temperatures over the range 318.15–333.15 K. The net retention values of n-alkanes were used to evaluate the London dispersive surface free energy γSL by three different methods, namely, the Donnet–Park, Dorris–Gray, and Schultz methods. The γSL values were found to increase from 318.15 to 323.15 K for all three methods and then decrease from 323.15 to 333.15 K. The γSL values were found to be slightly higher in the Schultz method when compared to the results of the Donnet–Park and Dorris–Gray methods. The specific free energy values ΔGaS and the specific enthalpy ΔHaS values have been calculated using the VN data of polar probes. The Guttmann Lewis acid–base parameters, Ka and Kb, were obtained using ΔHaS values and were found to be 0.217 and 1.518, respectively. The surface character (Kb/Ka) was found to be 7.0. The results revealed t...

A study of the thermodynamical interactions with solvents and surface characterisation of liquid crystalline 5-((S)-3,7-dimethyloctyloxy)-2-[[[4-(dodecyloxy)phenyl]imino]-methyl]phenol by inverse gas chromatography

An inverse gas chromatography (IGC) study of thermodynamic interactions of a new chiral calamitic liquid crystalline 5-((S)-3,7-Dimethyloctyloxy)-2-[[[4-(dodecyloxy)phenyl]imino]methyl]phenol (DODPIMP) with some solvents was presented. The retention diagrams of the solvents on the DODPIMP were plotted by specific retention volumes, Vg0 at temperatures between 373.2 and 393.2K. The Flory-Huggins interaction parameter, χ12∞, the weight fraction activity coefficient, Ω1∞ and selectivity coefficients, α, of the structural isomers were determined for the DODPIMP liquid crystal.To characterize the surface properties of, retention diagrams of several non-polar and polar solvents on the DODPIMP were plotted by net retention volumes, VN in the temperature range from 303.2 to 318.2K. The dispersive surface energy, the thermodynamic adsorption parameters and the acid–base constants of the compound in the crystalline phase were determined. The results indicated a basic character for the surface of DODPIMP at the studied conditions.

Surface thermodynamics of Efavirenz and a blend of Efavirenz with cellulose acetate propionate by inverse gas chromatography

The purpose of this paper is to study the effect of an excipient on the surface energetics of Efavirenz (EFV) drug. The net retention volumes, VN, for n-alkanes and polar solutes on the two columns, namely, EFV drug and a blend of EFV with cellulose acetate propionate have been measured by inverse gas chromatography. The dispersive surface free energy, , Lewis acid parameter, Ka, and Lewis base parameter, Kb, have been determined using VN values. The values are decreased linearly with increase of temperature for pure EFV as well as for the blend. Furthermore, the values of EFV are higher than in the blend, for example, values at T = 318.15 K for EFV, and for the blend are 28.09 ± 6.02 mJ/m2 and 28.30 ± 2.31 mJ/m2, respectively. The specific component of surface free energy has been obtained by the Schultz method as well as by the Dong et al. method. The values have been used to calculate Lewis acid-base parameters for the EFV as well as the blend. The Ka values for the EFV and the blend are almost similar, where as the Kb values are higher in EFV than in the blend. Similar trend in Ka and Kb has been observed in both methods studied. Copyright © 2015 John Wiley & Sons, Ltd.

Surface Thermodynamics of Poly(caprolactone) Diol by Inverse Gas Chromatography

Inverse gas chromatography was applied to evaluate the surface thermodynamic properties of biodegradable poly(caprolactone) diol (PCLD) in the temperature range 313.15–333.15 K with steps of 5 K. The net retention volumes, VN, were determined for the n-alkanes and polar solute probes. Dispersive surface free energy, , was calculated using the Schultz and Dorris-Gray methods, and at T = 313.15 K the values were found to be 19.87 and 21.61 mJm−2 respectively. The dispersive free energy decreased with increase in temperature. Surface Lewis acid parameter, Ka, and Lewis base parameter, Kb, were calculated following Gutmann’s approach. The Ka and Kb values were found to be 0.212 and 0.593 respectively, which revealed the basic nature of PCLD. The three components of the Hansen solubility parameters were determined using for the PCLD surface, and their variation with temperature was studied.

Surface characterization of cellulose acetate propionate by inverse gas chromatography

The purpose of this paper is to study the surface energetics of the polymer excipient cellulose acetate propionate (CAP) in the solid form. The net retention volumes, V N, for n-alkanes and polar solutes have been measured in the temperature range 353.15–403.15 K by inverse gas chromatography. The dispersive surface free energy, \( \gamma_{\text{S}}^{\text{d}} \), and Lewis acid–base parameters \( K_{\text{a}} \) and \( K_{\text{b}} \), have been determined using V N values. The \( \gamma_{\text{S}}^{\text{d}} \) values are decreased linearly with increase of temperature. The \( \gamma_{\text{S}}^{\text{d}} \) value at 353.15 K is 24.50 ± 1.54 mJ/m2, and the temperature gradient was found to be −0.287 mJ/m2/K1. The \( K_{\text{a}} \) and \( K_{\text{b}} \) values are 0.410 ± 0.021 and 1.708 ± 0.388, respectively, which suggest that the CAP solid surface contain relatively more basic sites. The K a and K b values of CAP are compared with the similar values obtained on the cellulose acetate butyrate solid surface.

Lewis Acid-base Properties of Cellulose Acetate Butyrate-Poly (Caprolactonediol) Blend by Inverse Gas Chromatography

Net retention volumes, VN, of n-alkanes and five polar solute probes on cellulose acetate butyrate – Polycaprolactonediol have been determined by inverse gas chromatography technique in the temperature range 323.15–393.15 K. The VN values of n-alkanes are used to calculate the dispersive component of surface energy of the blend. The values are decreasing nonlinearly with increase of temperature. The VN values of the five polar solutes are used to calculate the specific components of the enthalpy of adsorption and entropy of adsorption . The values are used to calculate Lewis acidity constant and basicity constant, which are 0.143 and 0.744, respectively.

Surface characterization of 2-hydroxypyrimidine sulphate by inverse gas chromatography

The net retention volumes, V N , of n-alkanes and polar probes on 2-hydroxypyrimidine sulphate (2-HPS) drug surface are determined at 323.15, 328.15 and 333.15 K using inverse gas chromatography. The dispersive surface free energy, \( \gamma_{S}^{d} \) of 2-HPS are evaluated by applying Schultz method as well as Dorris–Gray method and found that \( \gamma_{S}^{d} \) values are higher by 8 per cent in the latter method. The \( \gamma_{S}^{d} \) values are decreasing in both the methods with increase of temperature. The specific component of the free energy of adsorption, \( \Updelta G_{a}^{S} \), for polar probes are obtained by three methods proposed by Schultz et al., Saint Flour–Papirer and Sawyer–Brookman. The Lewis acid–base parameters, K a and K b , are calculated using \( \Updelta G_{a}^{S} \) values. The surface character value, S = (K b /K a ) according to the Schultz et al., is found to be 3.9 whereas the S value in the other two methods are found to be 6.2 and 5.6. The results demonstrate that the 2-HPS powder surface contain relatively more basic sites and can interact strongly in the acidic media.

Lewis acid-base properties of cellulose acetate phthalate-polycaprolactonediol blend by inverse gas chromatography

The net retention volumes, VN, of n-alkanes and five polar probes are determined on cellulose acetate phthalate–polycaprolactonediol blend column by inverse gas chromatography in the temperature range 323.15–363.15 K. The dispersive surface energy, , of the blend has been calculated using the VN values of n-alkanes and the at 333.15 K is 12.6 mJ/m2. The values are decreasing linearly with increase of temperature. The VN values of the five polar solutes are used to calculate the specific component of the enthalpy of adsorption, . The Lewis acid–base parameters, Ka and Kb, are derived using values and are found to be 0.019 and 0.403, respectively. The Ka and Kb values indicate that the blend surface contain more basic sites and interact strongly with the acidic probes. The acid–base parameters have been used to analyze the preferential interaction of the solid surface with acidic and basic probes. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers