Liquids Of Different Polarity Research Articles

A Procedure for Rational Probe Liquids Selection to Determine Hansen Solubility Parameters

AbstractHansen Solubility Parameters (HSP), viewed in the context of similarity whenever dispersion is focused, offer valuable insights into the surface characteristics of nanoparticles. However, existing methods for determining HSP via the sedimentation of nanoparticles require multiple probe liquids, resulting in time‐consuming, costly experiments with potential health risks. To address this, we developed a two‐step strategy that enables a systematic selection of liquids. The key element of the approach is to first identify the rough location of the Hansen sphere in the three‐dimensional Hansen space using a well‐chosen set of probe liquids of different polarities and chemical structures. Then, depending on the outcome of the first step, a particular choice of liquids is made for the final HSP determination. Taken together, the introduced procedure reduces the amount of required liquids for experiments from currently more than ten to a maximum of seven chosen based on a well‐defined, coherent methodology. Validation was performed on carbon black, non‐pigmentary nano‐scale titania, silicon/carbon composites, and lanthanum cobaltite particles, i. e., relevant materials that are commonly utilized in fuel cells, batteries, cyclohexene oxidation, catalytic combustion, photocatalysis, and heterogeneous Fenton reactions. The study showcases the potential to save time, costs, and efficiently determine HSP values in a comparable manner.

Hydrophilic–Hydrophobic Properties of the Surface of Modified Carbonate Fillers for Asphalt

The physicochemical modification of the filler allows changing the hydrophilic–hydrophobic properties and effectively influencing the processes occurring at the filler–binder interface, on which the physicomechanical characteristics of composites largely depend. The paper presents studies related to the modification of limestone-based filler effect on the degree of its hydrophobicity and wetting with liquids of different polarity, establishing the relationship between the characteristics of hydrophobized mineral powders and the adsorption capacity in relation to water. Using mechanochemical processing with hydrophobic components GF-1 and GF-2, it was possible to obtain fillers with a sufficiently high content of hydrophobic particles (58.2% and 85.9%, respectively). It was found that the results of the contact angle (123.6° and 114.5°, respectively) and the degree of hydrophobicity do not quite correlate with each other. It was noticed that the contact angle on the powder modified with GF-1 decreases with time. Studies of the powders’ thermal effects wetting of different polarity liquids via microcalorimetry allows us to establish that with an increase in the filler hydrophobicity degree, the integral heat of immersion decreases due to a significant decrease in the probability of chemical interactions between water and powder due to the adsorption of applied surfactants molecules on the limestone active centers. The revealed endothermic effects indicate the occurrence of physical interactions due to non-polar dispersion forces. Differences in the nature of heat release and heat absorption in modified fillers indicate significant differences in the composition and mechanism of action of the used surfactants, which affected the efficiency of hydrophobization. At the same time, a linear dependence of the moisture absorption and moisture indicators, determined by independent experiments, on the degree of hydrophobicity was established.

STABILITY OF SOME SILICONE LUBRICATING INTERLAYERS IN LIQUID-INFUSED COATINGS

One of the most actively developing research areas in materials science relevant to polyfunctional coatings is the creation of slippery liquid-infused porous surfaces (SLIPS) based on porous hydrophobic or hydrophilic materials filled with low-volatility viscous liquids (lubricants). In the present work, we have investigated the possibility of using two organosilicon liquids of different polarities, bis(trifluoromethylsulfonyl)imide dicationic ionic liquid and silicone oil, as lubricants for fabricating slippery coatings that reduce the adhesion of solid and liquid aqueous precipitations to aluminium oxide substrates. To calculate the stability of the films of such lubricants, we have employed the theory of van der Waals forces to study the refractive index dispersions and the dielectric properties of the liquids in the region of microwave relaxation. On the basis of experimentally obtained data, the dielectric permittivity spectra have been calculated as functions of imaginary frequency for the entire spectral range, as well as the contribution of the van der Waals forces to the stability of the disjoining pressure isotherms of the lubricant films on the hydrophobic and hydrophilic aluminium oxide substrates. The disjoining pressure isotherms obtained in this work have indicated that the ionic liquid used to prepare slippery coatings is a more durable lubricant than silicone oil, because its films retain their stability when the vapor phase is replaced by an aqueous medium over a wider range of thickness.

О ВЕРОЯТНЫХ МЕХАНИЗМАХ ВЗАИМОДЕЙСТВИЯ ПЕРЕМЕННЫХ ЭЛЕКТРИЧЕСКИХ ПОЛЕЙ С ЖИДКОСТЯМИ РАЗЛИЧНОЙ ПОЛЯРНОСТИ

An attempt was made to systematize and generalize the results of our own experiments, as well as available information on the impact of variable low-frequency electric fields on liquids of different polarities. The influence of the electrophysical impact was revealed on the examples of polar substances (containing hydrogen bonds) – water, ethanol, octane-non-polar alkane. The probable mechanism and forecast of practical use of those effects on a number of substances of different polarities were proposed. The article is debatable.

How drops start sliding over solid surfaces

It has been known for more than 200 years that the maximum static friction force between two solid surfaces is usually greater than the kinetic friction force—the force that is required to maintain the relative motion of the surfaces once the static force has been overcome. But the forces that impede the lateral motion of a drop of liquid on a solid surface are not as well characterized, and there is a lack of understanding about liquid–solid friction in general. Here, we report that the lateral adhesion force between a liquid drop and a solid can also be divided into a static and a kinetic regime. This striking analogy with solid–solid friction is a generic phenomenon that holds for liquids of different polarities and surface tensions on smooth, rough and structured surfaces. A liquid droplet is shown to slide across a solid surface subject to friction forces analogous with those between two solids. The phenomenon is generic, and closes a gap in our understanding of liquid–solid friction.

Dye Aggregates as New Stabilizers for (Mini)emulsions.

Water-soluble organic dyes such as fluorescein are widely used, mainly for coloration of, e.g., biological samples and groundwater tracing, and they are not obviously amphiphilic by molecular structure like surfactants. Here, we show that the dyes alone stabilize oil-in-water emulsions. Exemplarily, fluorescein is compared with the classical surfactant sodium dodecyl sulfate (SDS) by means of surface/interfacial tension, concentration of stabilizer and electrolyte, as well as pH. The principle can be extended to further classes of water-soluble dyes, which keep up with or exceed SDS by efficiency. Various organic liquids of different polarities can be employed and be polymerized in the case of styrene as disperse phase. Thus, surfactant free latex solely stabilized by water-soluble dyes is accessible. The emulsions can be destabilized by absorption of the dyes to hydrogels, and their complete removal is easily followed visually. The stabilization mechanisms are different for SDS and the dyes: The latter stabilize droplets not as monomers but by their aggregates as molecular scale Pickering stabilizers, which is a new concept of stabilization.

Insights into Mechanistic Models for Evaporation of Organic Liquids in the Environment Obtained by Position-Specific Carbon Isotope Analysis.

Position-specific isotope effects (PSIEs) have been measured by isotope ratio monitoring (13)C nuclear magnetic resonance spectrometry during the evaporation of 10 liquids of different polarities under 4 evaporation modes (passive evaporation, air-vented evaporation, low pressure evaporation, distillation). The observed effects are used to assess the validity of the Craig-Gordon isotope model for organic liquids. For seven liquids the overall isotope effect (IE) includes a vapor-liquid contribution that is strongly position-specific in polar compounds but less so in apolar compounds and a diffusive IE that is not position-specific, except in the alcohols, ethanol and propan-1-ol. The diffusive IE is diminished under forced evaporation. The position-specific isotope pattern created by liquid-vapor IEs is manifest in five liquids, which have an air-side limitation for volatilization. For the alcohols, undefined processes in the liquid phase create additional PSIEs. Three other liquids with limitations on the liquid side have a lower, highly position-specific, bulk diffusive IE. It is concluded that evaporation of organic pollutants creates unique position-specific isotope patterns that may be used to assess the progress of remediation or natural attenuation of pollution and that the Craig-Gordon isotope model is valid for the volatilization of nonpolar organic liquids with air-side limitation of the volatilization rate.

Research of Surface Properties of Fillers for Polymers

The behavior of filler particles in the polymer matrix on a physical model representing the suspension of solid particles in the apolar liquid has been studied. Relative sedimentation volumes of powder components included in the polymer composition for the cable insulation in liquids of different polarity have been identified. The dependence of the effect of hygroscopic powder fillers on the relative sedimentation volume of powders and a ratio of wetting has been studied. It has been found that hydrophobic interactions are not observed at the surface of completely dry materials placed in liquids of different polarity. Consequently, the role of the filler is actually to prevent adsorption of moisture from the air on the surface of the particles, to reduce their hygroscopicity. It is proposed to assess the degree of water-repellency of the particles of powdered fillers by the measurement of their maximum hygroscopicity.

Position-specific Carbon Isotope Fractionation gives Insights into Mechanistic Models for Evaporation of Organic Liquids in the Environment

This work describes position-specific isotope effects (IE) measured by iq 13C-NMR during the evaporation of 8 different liquids of different polarities under 4 evaporation modes (passive evaporation, air-vented evaporation, low pressure evaporation and distillation). The observed effects are used to assess the question whether for carbon isotopes in organic liquids the use of the Craig-Gordon isotope model is valid. It is shown for five liquids that the overall IE include vapour-liquid IE which are strongly position-specific in polar compounds and less specific in apolar compounds, and a diffusive effect for which is not position-specific. The diffusive effect is diminished under wind and low pressure. After evaporation, the position-specific isotope pattern created by liquid-vapour IE is still quite reasonably preserved in these five liquids, which have, like water, an air-side limitation for volatilisation. Three other liquids in this study with limitations rather or fully on the liquid side differed from this pattern. It is concluded that evaporation of organic pollutants creates a unique position-specific isotope pattern that may be used to assess the progress of remediation or natural attenuation, and that the Craig-Gordon isotope model is valid for the volatilization of organic liquids with air-side limitation of the volatilization rate.

Synthesis and Characterization of New Silica‐Titania Mixed Oxides Obtained by Sol‐Gel Technique

AbstractSummary: Although titanium dioxide has a high surface area, it is not thermally stable and its surface area decreases strongly at high temperature due to phase transformation and crystal growth. To improve the thermal stability of titanium dioxide, the synthesis of mixed oxides can be an elegant approach. In this study different experimental variables for the synthesis and characterization of new titania‐silica mixed oxides intended to be used as fillers have been proposed. To manufacture the mixed oxides, different tetraethylortosilicate (TEOS)/Tetrabutyl orthotitanate (TBTi) mixtures in different ratio, ethanol as solvent, and acetic acid as catalyst were used via sol‐gel synthesis route. These oxides were characterized by transmission electron microscopy coupled with EDX analysis (TEM‐EDX), optical microscopy, X‐ray diffraction, textural properties, and pH measurements and wettability with liquids of different polarity.

Stability of Lipogels with Low Molecular Mass Gelators and Emollient Oils

The influence of preparation methods on stability of lipogels was studied. The objectives of this study were to evaluate the ability of different low molecular solid ingredients used as excipients in pharmaceutical and cosmetical products to form lipogels with emollient liquids of different polarities as well as to evaluate the stability of the lipogels obtained and the spreading ability of stable lipogels. The lipogels were prepared by heating the mix of oil and gelator a 100°C with two different forms of cooling: slow cooling of the without stirring and quick cooling with stirring. The stability tests were one year of storage at room temperature, centrifugation and three months at 40°C. None of the lipogels prepared with slow cooling and without stirring were stable in all stability tests. Eight of the formulations with quick cooling and stirring were stables in all stability tests: six with 12-hydroxystearic acid, one with hydrogenated castor oil, and one with beeswax as gelators. The lipogels with 12-hydroxystearic acid as gelator do not spread on skin or form clusters that spread after pressing with the fingers. The two lipogels with castor oil have good spreading ability on the skin.

Effects of Laser Irradiation on Surface Properties of Poly(ethylene terephthalate)

The influence of the ArF laser irradiation on the surface energy of poly(ethylene terephthalate) was investigated. An effort was also made to elucidate the physical and chemical phenomena affecting surface energy (SE). The surface chemical changes, occurring upon the irradiation, were monitored by X-ray photoelectron spectroscopy (XPS) and the changes in the surface geometrical structure were investigated by atomic force microscopy (AFM). The contact angle values obtained with test liquids of different polarity (water and diiodomethane) were measured while the surface energy was calculated by the Owens–Wendt method. The nature of the physico-chemical changes occurring in the poly(ethylene terephthalate) surface layer upon ArF laser irradiation depended mostly on the energy per unit area of the laser pulse and the number of the laser pulses. The polar and dispersive components of the surface energy increased as a result of increasing the number of the laser pulses of energy which were below that of the PET ablation threshold.

Control of Wettability of Polymers by Surface Roughness Modification

Most polymeric materials, particularly polyolefins and their derivatives, present a low surface energy which is the cause of their poor wettability and limits processes such as adhesive bonding, painting, or metalizing. Many methods have been developed and used to modify polymer surfaces for improved wetting, including mechanical treatments, wet-chemical treatments with strong acids or bases, and exposure to flames or corona discharge. In this paper the improvement of wetting properties of several polymeric materials widely used in the automotive industry, such as high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and silicone, is studied by means of surface mechanical abrasion using sandpapers of different grain sizes (1000, 180 and 80). Measurements of the surface roughness are performed using a Hommel Tester T8000 device equipped with a diamond stylus, which provides data on the arithmetic average roughness R a parameter and Abbott–Firestone curve. Variations in the polymers surface energy (SE) are estimated through contact angle measurements using five test liquids of different polarities. Both components of the SE, dispersion (σ D) and polar (σ P), as well as total (σ T) at different conditions of treatment are analyzed using the Owens–Wendt–Rabel–Kaelble (OWRK) method. Morphological changes induced in the surface are analyzed by Scanning Electron Microscopy (SEM). Additionally, measurements of the static friction coefficient (μ s) are carried out by the standard method ASTM D 1894-08. A slight enhancement in surface wettability is found with the mechanical abrasion pre-treatment from the SE increase. Finally, a higher value of μ s is achieved for the abraded specimens as the normal force acting onto the system is increased.

Natural surfactants used in cosmetics: glycolipids

Cosmetic surfactant performs detergency, wetting, emulsifying, solubilizing, dispersing and foaming effects. Adverse reactions of chemical synthesis surfactant have an effect on environment and humans, particularly severe in long term. Biodegradability, low toxicity and ecological acceptability which are the benefits of naturally derived surfactant that promises cosmetic safety are, therefore, highly on demand. Biosurfactant producible from microorganisms exhibiting potential surface properties suitable for cosmetic applications especially incorporate with their biological activities. Sophorolipids, rhamnolipids and mannosylerythritol lipids are the most widely used glycolipids biosurfactant in cosmetics. Literatures and patents relevant to these three glycolipids reviewed were emphasizing on the cosmetic applications including personal care products presenting the cosmetic efficiency, efficacy and economy benefits of glycolipids biosurfactant.

Environmental Effects on the Single Molecule Conductance of bis(thiahexyl)oligothiophenes

AbstractSimple alkanedithiols exhibit the same molecular conductance whether measured in air, under vacuum or under liquids of different polarity. Here, we show that the presence of water ‘gates’ the conductance of a family of oligothiophene–containing molecular wires, and that the longer the oligothiophene, the larger is the effect; for the longest example studied, the molecular conductance is over two orders of magnitude larger in the presence of water, an unprecedented result suggesting that ambient water is a crucial factor to be taken into account when measuring single molecule conductances (SMC), or in the design of future molecular electronic devices. Theoretical investigation of electron transport through the molecules, using the ab initio non-equilibrium Green's function (SMEAGOL) method, shows that water molecules interact with the thiophene rings, shifting the transport resonances enough to increase greatly the SMC of the longer, more conjugated examples.

Photochemical Surface Modification of Polyethylene Films by New Azidobenzenesulfonamides

New azidobenzenesulfonamides are synthesized. Their photophysical and photochemical properties have been investigated. The photophysical properties of these compounds were investigated by 1H NMR, IR, and UV spectroscopy. The surface photomodification of polyethylene (PE) films by using new azidobenzenesulfonamides is carried out. The wetting angles for three liquids of different polarities (water, formamide, and diiodomethane) have been studied to estimate the surface modification performed. The obtained wetting angles are used for the determination of the surface free energy γS (γ), as well as its polar , dispersive Owens–Wendt , Lifshits–van der Waals γLW, and acid-base γAB components, by applying the Lifshits–van der Waals/acid-base methods.

Static–dynamic sequential superheated liquid extraction of phenols and fatty acids from alperujo

Superheated liquids of different polarity have been used for sequential extraction of fatty acids and phenols from alperujo. Multivariate methodology has been used to optimise the static-dynamic extraction. Forty-two minutes are required to complete extraction (20 mg/kg of fatty acids and up to 2,200 mg/kg of hydroxytyrosol in the raw material used). The efficacy of the extraction has been demonstrated and compared with that of conventional methods (Folch and stirring-based methods for fatty acids and phenols, respectively), which needed 4.5 and 24 h for the extraction of fatty acids and phenols, respectively. The non-polar and polar extracts were injected into GC-MS and HPLC-MS-MS equipment, respectively, for individual separation-quantification of the target compounds. The simplicity of the experimental setup and the low costs of the raw material make the proposed method advisable when extraction of both fractions is required.

Production of biosurfactant by Bacillus subtilis LB5a on a pilot scale using cassava wastewater as substrate

The main characteristic of biosurfactants is their property of reducing the superficial and interfacial tension between two immiscible liquids of different polarities. The main obstacle to the application of biosurfactants is the high production costs, the use of alternative substrates being indicated to solve this problem. This work report the production of biosurfactant by Bacillus subtilis LB5a on a pilot scale using cassava wastewater as the substrate, and the study of the parameters related to its production. The cassava wastewater was heated, centrifuged and poured into a 40-liter batch pilot bioreactor adapted for simultaneous foam collection during the fermentative process. The temperature was maintained at 35 degrees C, agitation at 150 rpm and aeration 0.38 vvm during the first 12 h, and 0.63 vvm for the rest of the process. Samples of liquid fermentate were collected at regular intervals for the analysis of total carbohydrates, reducing sugars, pH, CFU/mL count and superficial tension. The foam was centrifuged and the biosurfactant purified. The kinetic data of the process showed that both the microbial population, which reached a maximum after about 24 h, and the foam production of 10.6 L, peaked between 24 and 36 h, coinciding with the greatest production of biosurfactant. The yield of semi-purified surfactant in the foam was 2.4 g/L. The superficial tension of the medium was reduced from 51 to 27 mN/m and the critical micellar concentration was 11 mg/L, which, in principle, characterizes it as a good tensoactive agent. As a function of its composition and productivity, cassava wastewater was identified as a good substrate for the production of the biosurfactant.

Prenematic Behavior of the Electric-Field-Induced Increment of the Basic Thermodynamic Quantities of Isotropic Mesogenic Liquids of Different Polarity

Temperature dependences of the static dielectric permittivity and its derivative, obtained for isotropic mesogenic liquids composed of the molecules of different polarity in relation to the basic thermodynamic quantities (internal energy, entropy, and Helmholtz free energy), are analyzed. A role of the molecular polarity in the dielectric behavior of the liquids in the vicinity of the isotropic to nematic phase transition is discussed.

Intrinsic and Effective Acidity Study of Niobic Acid and Niobium Phosphate by a Multitechnique Approach

The acidity properties of niobic acid (Nb2O5·nH2O) and niobium phosphate (NbOPO4) surfaces have been studied by different methods and under various conditions in order to obtain comprehensive information about the number, strength, and strength distribution of their acid sites. Four base probe molecules of different basicities (ammonia, pyridine, 2-phenylethylamine, and aniline) have been used. Gas−solid and liquid−solid titrations by these basic probes have been performed, using static or dynamic adsorption (calorimetry linked to volumetry, reaction calorimetry, pulse flow volumetry using a HPLC apparatus) and desorption (thermogravimetric analysis) techniques. The intrinsic surface acidities of the two solids, determined under vacuum or inert atmospheres, were compared with the effective acidities measured in liquids of different polarities and proticities (decane, cycloexane, toluene, methanol, and isopropanol). The effective acidities of the two surfaces could be related to their catalytic activities measured in the fructose dehydration reaction in aqueous phase. The superior catalytic activity of niobium phosphate compared to niobic acid is related to its higher number of surface sites maintaining acid characteristics even in highly polar and protic solvents.