Oleic Acid Surfactant Research Articles

OLEIC ACID AS AN EFFECTIVE SURFACTANT FOR POLY (LACTIC ACID) MICROPARTICLE: A DFT STUDY

This study aimed to investigate the interaction of oleic acid (OA) with poly (lactic acid) (PLA) microparticle in chloroform and dichloromethane phases using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The study was conducted at the B3LYP-D3/6-31+G** level of theory. The binding energy, dipole moment. and thermodynamic parameters show that the interaction between OA and PLA via C=O….H-O bonds in the most stable state (state I) in the chloroform phase is stronger than in the dichloromethane phase. Negative values of the thermodynamic parameters in the most stable complex and the MEP graphs showed that OA has a positive impact on the adsorption behavior of the PLA. The presence of OA altered the structure of PLA based on theoretical UV-Vis and Infrared (IR) spectra. The findings revealed that using the OA surfactant can improve dispersion and compatibility with the PLA matrix. For citation: Safa A.N., Sheibani A., Baei M.T., Sayyed-Alangi S.Z., Lemeski E.T. Oleic acid as an effective surfactant for poly (lactic acid) microparticle: A DFT study. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 65-72. DOI: 10.6060/ivkkt.20246706.7069. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Design, spectral, molecular modeling, antimitotic, analytical and mechanism studies of phenyl isothiocyanate Girard's T derived metal complexes

The ligand N-{[(phenyl amino) thioxomethyl] hydrazino carbonyl methyl} trimethyl ammonium chloride (PTHAC) was prepared by the refluxing phenyl isothiocyanate and Girard-T (trimethyl ammonium-acethydrazide) in a molar ratio (1:1). The metal complexes derived from NiCl2.6H2O, CuCl2.2H2O and Co(CH3COO)2.6H2O were synthesized and purified. The PTHAC and its Cu(II), Co(II), and Ni(II) metal complexes(1–3) were characterized using a variety of various instrumental performances such as elemental analysis, magnetic moment, spectra (IR, UV–Vis, 1H NMR, mass) and thermal analysis (TGA and DTG).The results of element analysis, magnetic moment, spectra (IR, UV–Vis, 1H NMR, mass), and thermal (TGA and DTA) analyses provide the structures of the produced ligand and its (1–3) complexes. According to the spectroscopic results, PTHAC acts as an O, N and S tridentate donor, creating a mononuclear complex with copper(II), cobalt(II), and nickel(II) ions with an octahedral geometry. All of the atomic properties, including bond lengths, bond angles, HOMO, LUMO, dipole moments, and charges, have been determined. The cytotoxic activities of the PTHAC and the produced (1–3) complexes against breast carcinoma cells have been studied and correlated to the molecular modeling. When compared to the free ligand, CoII-L, and NiII-L, the CuII-L complex inhibits breast cancer cell growth more effectively. Furthermore, the PTHAC ligand was successfully applied for separation via flotation and spectrophotometric determination of Co(II) in several natural water, certified ore and pharmaceutical samples using oleic acid surfactant (HOL). At pH 6.5, PTHAC reacted with Co(II) to create a dark green (1:1) Co(II):PTHAC complex that was floated significantly using oleic acid (HOL) surfactant. The different experimental variable affecting the separation procedure e.g. pH, concentration of Co(II), HOL, PTHAC, temperature etc.…, were investigated. Co(II) had a linear range of (0.1–7.0) mgL−1. In the aqueous and scum layers, the molar absorptivities for the coloured complex are 0.14 × 104 and 0.16 × 105Lmol−1 cm−1, respectively. The LOD was 0.04 mgL−1, which is related to Sandell sensitivity of 3.7 × 10−3 µg cm−2 with a preconcentration factor of 200 and a RSD, % (n = 5) less than 4.2%. In addition, the mechanisms involved in the process of coordination of PTHAC with Cu(II), Co(II) and Ni(II) and the mechanism involved in the process of flotation of the PTHAC-Co(II) complex using HOL surfactant were elucidated.

Physical properties with high specific loss power of magnetite (Fe3O4) synthesized via thermal decomposition technique

Magnetic iron oxide nanoparticles have versatile applications in biomedical science that require control over shape and size distribution. Thermal decomposition is one of the best methods for controlling the size and shape of produced nanoparticles (NPs). The size distribution can be tuned (5–30 nm) by varying the reaction environment such as precursor concentration, amount of solvent used, temperature ramp, and reflux time. Iron oleate was used as a precursor solution and heated up to reflux temperature (310 °C) for 10 min within the oxygen-free environment by applying N2 gas flow. The XRD pattern confirmed the formation of NPs with a crystallite size of 17 ± 2.45 nm. Transmission electron microscope images showed moderately cubic shapes with a mean particle size of 28.67 ± 7.12 nm. Magnetic properties such as saturation magnetization, coercivity, and remanence were calculated at 23.48 emu/gm, 33 Oe, and 0.6 emu/gm, respectively, which indicated the ferromagnetic nature of the NPs. The Verwey transition was identified from the magnetization vs temperature (FC-ZFC) plot. The bondings of the oleic acid surfactant with the produced NPs were confirmed from Fourier transformation infrared spectroscopy (FTIR) data analysis. For the application of hyperthermia, the hydrophobic phase was transferred to the hydrophilic phase using cetyltrimethylammonium bromide, which was assured by the FTIR data analysis. The hyperthermia heating of NPs was measured for different concentrations of NPs (0.25, 0.5, 1, 2, and 4 mg/ml), from which specific loss power (SLP) was calculated. Among them, 0.25 mg/ml produced the most prominent SLP (2149 ± 309 w/g) that can be applied for targeted cancer treatment.

Divalent transition metal complexes of nitrogen, oxygen and sulfur containing ligand: design, structural, spectral, pH-metric, theoretical molecular modeling, analytical and mechanism studies

In the present study, the 1-Nicotinoyl-4-phenyl thiosemicarbazide (H2NPT) multidentate nitrogen, oxygen and sulfur containing ligand is being synthesized in a simple single step reaction by condensing 1:1 molar ratio of ethanolic solutions of both phenyl isothiocyanate and nicotinoyl hydrazine. The prepared H2NPT and its complexes with Co2+, Ni2+ and Zn2+ and Cu2+ were characterized by pH-metric titrations, elemental analysis, FTIR, electronic spectra and thermogravimetric (TGA) analyses. The association constant of the ligand and the stability constants of its complexes were calculated by pH-metric measurements in 50% ethanol–water mixture. Also, DFT method was used to draw the geometry of all compounds and the parameters such as bond lengths, bond angles, dipole moment, Frontier orbitals (HOMO, LUMO), MEP and other energetic parameters (optical energy gap, softness, hardness, electronegativity) were evaluated. The prepared H2NPT reacted with Co2+, Ni2+ and Zn2+ and Cu2+ metal ions to form colored precipitates that were readily floated to the surface solution using oleic acid (HOL) surfactant with vigorous shaking of the flotation cell. The heavy metals' concentrations in the dissolved precipitates are determined by flame atomic absorption spectrometry (FAAS). The different parameters affecting the flotation process were thoroughly investigated, viz. pH of sample solution, concentration of ligand, metal ions and HOL, temperature and interfering ions. Nano-gram quantities of Cu2+, Co2+, Ni2+ and Zn2+in 1500-ml samples are quantitatively determined with 1-Nicotinoyl-4-phenyl thiosemicarbazide (H2NPT) at pH 3.0–6.5 for Cu2+ and at 7.0–7.5 for Co2+, Ni2+ and Zn2+. The concentrations of these heavy metals are increased 300-fold. Interferences, on the flotation process, from various foreign ions were avoided by adding excess H2NPT. The mode of chelation between H2NPT and the investigated metal ions is proposed to be through the S, N and/or O atoms of the ligand. The mechanism of flotation is proposed to be due to an electrostatic interaction between the HOL surfactant and the formed metal–ligand complexes through H-bond formation. The proposed multi-element flotation methodology has been utilized for the determination of the analytes in certified reference materials, alloys, synthetic mixtures and in water samples with a recovery % more than 90% and a relative standard deviation (RSD), as a precision < 2%.

Elucidation of the synergistic mechanism of nano silicon carbide and titanium nitride as highly efficient additives of polyalphaolefin on strengthening the lubrication performance of movable contact interface

This study comprehensively investigated physicochemical and tribological performance of polyalphaolefin (PAO4) oil introducing oleic acid (OA)-functionalized SiC/TiN hybrid nanomaterials. The dispersion stability, wettability, thermal stability, and friction properties of the nanolubricants (NL) system were greatly improved following the application of hybrid NL. Additionally, the anti-wear and reducing-friction behavior were assessed via a four-ball tribometer. The results showed that the COF and WSD values of wear scar lubricated by hybrid NL were greatly reduced by approximately 32.7% and 35.1%, respectively, compared with the base oil. Finally, it is strongly confirmed that the significant improvement of friction performance is mainly due to improved interfacial effect of NL, the stable chemical tribo-film generated onto the friction surface, and the synergistic effect among SiC, TiN nanoparticles, and OA surfactant.

Combustion characteristics of gasoline fuel droplets containing boron-based particles

Boron-based particles are dense energy carriers that are promising for a future carbon-neutral world, to store and transport abundant energy. Although it is prominent as a slurry fuel component in liquid aviation fuels, its effects on the combustion behavior of traditional hydrocarbon fuels used in public or industrial areas have not yet been clarified. In this study, combustion characteristics of gasoline-based fuel droplets containing 86–88%, and 95–97% < 1 µm amorphous boron, 10 µm AlB12, 28 – 35 µm MgB2 particles and 1% oleic acid surfactant. The experimental process was recorded via a high-speed camera and a thermal camera. The results showed that the ignition delay time was reduced in all gasoline-based fuels containing boron-based particles. The fuels with the lowest extinction time were gasoline-based fuel droplets containing AlB12 particles (∼1245 ms). Amorphous boron particles were transported to the flame region more than other particles and caused severe atomization phenomena. The highest maximum flame temperature for gasoline droplets at 2.5% particle load was recorded in high-purity amorphous boron particles with 537 K. At 7.5% particle load, the highest flame temperature and agglomerate temperature were observed at 513 K and 653 K, respectively, in gasoline droplets containing high-purity amorphous boron particles. In electric field tests, the shortest extinction time was detected for gasoline droplets with MgB12. Also, the addition of amorph boron particles into gasoline increase of 4.6% was seen in the flame speed. Droplet diameter regression plots show that particulate gasoline-based fuel droplets exhibit a decreasing trend, mostly following the D2-law. It has been revealed low-cost amorphous boron derivatives can be an important energy carrier for liquid hydrocarbon fuels.

An Experimental Investigation of the Tribological Performance and Dispersibility of 2D Nanoparticles as Oil Additives

The present study aims to investigate the tribological performance of 2D nanoparticles such as graphene (G), molybdenum disulfide (MoS2), hexagonal boron nitride (hBN), and reduced graphene oxide (rGO) as gear lubricant additives. A new method of additive doping in gear lubricants was proposed and examined in terms of the degradation of lubricants. The additives were energized by ultrasonication, thermal agitation, and mechanical shearing to enhance the dispersibility and stability, which were confirmed using visual and rheological analysis. Further, the tribological performance of the nano-additives was studied by doping them in fresh lubricants, chemically degraded lubricants, and chemically degraded lubricants with surfactants. The results indicate that surface roughness and the method of mixing play a crucial role in reducing wear. The nano-additives exhibit an inverse relationship with the roughness, and their agglomeration results in a decline in performance. To mitigate agglomeration, oleic acid surfactant was employed, which diminished the effects of nano-additives and degraded the lubricant. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analysis revealed that the oleic acid and deteriorating reagent work synergistically, leading to enhanced wear volume and reduced friction. The nano-additives were characterized using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Overall, the study presents a comprehensive plan for new method of additive mixing, stability, dispersibility and tribological performance of the selected 2D nanoparticles.

Improved biocompatibility of anodized titanium implants by MnO nanoparticles

The surface addition of biocompatible metal oxide nanoparticles can significantly affect the physical, chemical, and biological properties of anodized titanium implants. Manganese is an important element for bone growth and regeneration and is essential for the body's vital systems. In this study, the biological properties of anodized titanium implants decorated with MnO nanoparticles were studied. At first, the effect of anodic oxidation voltage (15 V, 20 V, and 25 V) on the microstructure of titanium oxide nanotubes (TNTs) was investigated. Microstructural studies showed that the diameters of TNTs are increased by raising the applied voltage. Prepared TNTs with the applied voltage of 25 V exhibited a more uniform structure with an average inner diameter of 102 ± 15 nm. In the next step, MnO nanoparticles were synthesized through the thermal decomposition method. The effects of different surfactants, such as oleic acid and oleylamine, and various solvents, including dibenzyl ether and octadecene, on the size and morphology of the synthesized nanoparticles were studied. The results indicated that the MnO nanoparticles synthesized by dibenzyl ether solvent and oleic acid surfactant showed the smallest size and uniform morphology. Finally, the synthesized TNTs were decorated by the optimized MnO nanoparticles using the hydrothermal technique. X-ray diffraction (XRD) analysis was used to phase characterization. Microstructural studies were carried out by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. MTT and cell morphology tests were carried out for the biocompatibility evaluation of the specimens. The results showed that the anodized titanium decorated with MnO nanoparticles indicated the highest cell viability compared to the anodized and untreated samples. Microstructural studies demonstrated that the cells attached to the surface and spreading of filopodia in the anodized titanium decorated with MnO nanoparticles are higher than the other samples.

Stability and potential degradation of the α',β'-epoxyketone pharmacophore on ZnO nanocarriers: insights from reactive molecular dynamics and density functional theory calculations.

We investigate the structure and dynamics of a zinc oxide nanocarrier loaded with Carfilzomib, an epoxyketone proteasome inhibitor developed for treating multiple myeloma. We demonstrate that, even though both bare and functionalized zinc oxide supports have been used for drug delivery, their interactions with the reactive functional groups of the ligands could be detrimental. This is because pharmacophores like α',β'-epoxyketones should preserve the groups required for the drug activity and be capable of leaving the vehicle at the target site. Earlier studies showed that even when ZnO is functionalized with oleic acid surfactants, the drug could reach parts of the surface and remain stably adsorbed. Herein, we have used reactive molecular dynamics simulations and quantum chemistry calculations to explore the potential interactions of the Carfilzomib functional groups with the typical surfaces of ZnO supports. We have found that Carfilzomib can adsorb on the (0001)Zn-terminated polar surface through the carbonyl oxygens and the epoxyketone moiety. These strong connections could prevent the drug release and induce the epoxy ring opening with its consequential inactivation. Therefore, regulating the dosage to maintain the desired level of drug bioavailability is paramount. These findings emphasize the need for appropriate carrier functionalizations to efficiently entrap, transport, and release the cargo at the target sites and the crucial role played by predictive/descriptive computational techniques to complement and drive experiments to the most appropriate selections of the materials to optimize drug delivery.

The role of oleic acid on the structural changes of graphite nanoplatelets in enhancing the tribological performance of a palm oil-based lubricant

The current work investigates the structural changes of graphite (CG) when employed as an additive in palm kernel oil (PKO)-based nanolubricants without and with oleic acid (OA) surfactant. A four-ball tribotester was used to study the tribological performance of PKO + CG nanolubricants. PKO + CG nanolubricants with OA surfactant outperformed others, demonstrating significant reductions in coefficient of friction (20.5%) and wear scar diameter (9.1%) as compared to the PKO base lubricant. Exfoliation of graphite was facilitated during sliding due to the impact of shear force. A transmission electron microscopy structural study showed that the presence of OA surfactant in nanolubricants stimulated the formation of highly exfoliated graphite, resulting in the formation of scrolling graphite. Furthermore, when lubricated with PKO + CG + OA nanolubricants, Raman spectroscopic study of the worn surface reveals the formation of a more ordered tribofilm at the friction contact. The findings highlight graphite structural changes as the major factor in improving tribological performance. These results could help us learn more about the main mechanism of graphite as a lubricant additive and how structural changes affect tribological performance.

Understanding of Contradiction on Concentration Effect on Stability, Physical Properties, Evaporation and Microexplosion Characteristics of Al/JP-10/Oleic Acid Nanofluid Fuel.

An Al/JP-10/oleic acid nanofluid fuel system has demonstrated potential in advanced combustion for aviation turbine engines. To improve the energy density of nanofluid fuel, a higher Al concentration requirement needs to be met. Correspondingly, a higher surfactant oleic acid concentration is required to maintain better dispersion stability. The increment of Al and oleic acid concentrations results in more frequent microexplosions, but a slower evaporation rate. Therefore, this paper proposes to deeply understand the contradiction of the concentration effect on the stability, physical properties, evaporation and microexplosion characteristics and obtain the best Al and oleic acid concentrations to maintain the most suitable comprehensive performance. Experiments on the stability, physical properties, evaporation and microexplosion characteristics were conducted, respectively. The analysis and discussion were then made to reveal the Al and oleic acid concentration effect on the stability, physical properties, evaporation and microexplosion characteristics. The results show that the optimum mass ratio of Al:oleic acid is 1:2 for the nanofluid fuels with Al concentrations of 2.5 wt.% or below, 1:2.5 for 5.0 wt.% or above to obtain the best stability. The physical properties of the nanofluid fuels such as density, surface tension and viscosity are linear, quartic and quadratic functions of Al concentration, respectively, relating to the internal flow and microexplosion of fuel droplets. With increasing oleic acid and Al concentration, the evaporation rates reduced, and the microexplosions became more frequent and intense. At a high ambient temperature of 600 °C, the evaporation rates were kept almost equivalent for JP-10, JP-10/oleic acid, and Al/JP-10/oleic acid fuels. It was found that the increment of ambient temperature can compensate for the reduction of the evaporation rate owing to the addition of oleic acid and Al nanoparticles, improving the evaporation and microexplosion performance.

Exploring the Nanostructures Accessible to an Organic Surfactant Atmospheric Aerosol Proxy.

The composition of atmospheric aerosols varies with time, season, location, and environment. This affects key aerosol properties such as hygroscopicity and reactivity, influencing the aerosol’s impact on the climate and air quality. The organic fraction of atmospheric aerosol emissions often contains surfactant material, such as fatty acids. These molecules are known to form three-dimensional nanostructures in contact with water. Different nanostructures have marked differences in viscosity and diffusivity that are properties whose understanding is essential when considering an aerosol’s atmospheric impact. We have explored a range of nanostructures accessible to the organic surfactant oleic acid (commonly found in cooking emissions), simulating variation that is likely to happen in the atmosphere. This was achieved by changing the amount of water, aqueous phase salinity and by addition of other commonly coemitted compounds: sugars and stearic acid (the saturated analogue of oleic acid). The nanostructure was observed by both synchrotron and laboratory small/wide angle X-ray scattering (SAXS/WAXS) and found to be sensitive to the proxy composition. Additionally, the spacing between repeat units in these nanostructures was water content dependent (i.e., an increase from 41 to 54 Å in inverse hexagonal phase d-spacing when increasing the water content from 30 to 50 wt %), suggesting incorporation of water within the nanostructure. A significant decrease in mixture viscosity was also observed with increasing water content from ∼104 to ∼102 Pa s when increasing the water content from 30 to 60 wt %. Time-resolved SAXS experiments on levitated droplets of this proxy confirm the phase changes observed in bulk phase mixtures and demonstrate that coexistent nanostructures can form in droplets. Aerosol compositional and subsequent nanostructural changes could affect aerosol processes, leading to an impact on the climate and urban air pollution.

Synthesis of iron oxide nanoparticles by decomposition of iron-oleate: influence of the heating rate on the particle size

Nanoparticles from transition metal oxides can be synthesized in various ways. A common synthesis route uses metal-oleate complex precursors that can be thermally decomposed, leading to crystalline metal-oxide nanoparticles with a narrow size distribution. The morphology of nanoparticles synthesized in such a way is strongly influenced by the synthesis parameters. In this study, the influence of the heating profile during the decomposition of iron oleate precursor on the size of the resulting iron oxide nanoparticles in the presence of surfactants was investigated. As surfactants oleic acid and sodium oleate were utilized for nanoparticle synthesis allowing additionally for shape control. Most of the prepared nanoparticles reveal a characteristic core–shell structure. The dominant structure is the cubic spinel structure of maghemite (γ-(Fe3+)2O3) or magnetite (Fe2+(Fe3+)2O4), while in the core region of the nanoparticles, wustite (Fe2+O) is present. The heating rate applied for the nanoparticle synthesis was systematically varied from 1 to 30 °C/min, while all other parameters were kept constant. A strong increase of the particle size (> 20 nm) was observed for low heating rates, which could be explained qualitatively in the frame of the LaMer model and allows for fine-tuning and control of the particle size.

Effects of Different Fatty Acids as Surfactants on the Rheological Properties of Kerosene-Based Magnetic Fluids

Three types of surfactants (oleic acid, linoleic acid, and a mixture of oleic acid and linoleic acid) were coated on ferromagnetic particles, which were dispersed in kerosene to prepare magnetic fluids, to study the effect of different fatty acids as surfactants on the rheological properties of magnetic fluids. The particles were analyzed by XRD, TEM, FT-IR, and VSM. Furthermore, a rheometer was used to examine the rheological properties of kerosene-based magnetic fluids dispersed with various surfactants. The yield stress at different magnetic fields was calculated by fitting the Herschel–Bulkley model. The fitted curve and the observed values of mixed fatty acids are identical. The graphs of viscosity increase with the shear rate for each magnetic fluid were measured at constant magnetic field strengths. At constant shear rates, the curves of viscosity increase with magnetic field intensity were measured. In the absence of a magnetic field, the relative change in viscosity from 40°C to 0°C was observed. The rheological measurements of the mixed fatty acid-dispersed ferrofluid with a rising magnetic field at a constant shear rate are smoother than the single-fatty-acid-dispersed ferrofluid, indicating that it is more stable. As the temperature is dropped, the viscosity–temperature curve evidence that mixed fatty acids as surfactants can lower the proportion of magnetic fluid viscosity rise.

Microspheres assembled by WO3-x nanoparticles under action of dual surfactants: Structure and photoluminescence properties

Substoichiometric tungsten oxide (WO3-x) nanomaterials become the promising next-generation semiconducting materials due to the presence of oxygen vacancies. This paper reports the synthesis and photoluminescence (PL) properties of the WO3-x microspheres assembled by the WO3-x nanoparticles (NPs) in the acetic acid solution containing butyric and oleic acid surfactants. The formation of the WO3-x microspheres results from diffusion of dual surfactant molecules in the clusters formed by the WO3-x NPs due to their non-uniform distribution. When the WO3-x NPs in the clusters are completely covered by dual surfactant molecules, the steric repulsion is enough strong to form the WO3-x microspheres through the assembly of the WO3-x NPs. The PL studies indicate that they generate the ultraviolet, blue, green, red and near infrared PL bands and the PL emission from the WO3-x microspheres features the PL quenching. The generation of different PL bands is related to the transitions between the bands and between the defect levels and the relaxation of polaron formed by the coupling between lattice distortion and carries. The PL quenching is linked to the coupling between the WO3-x NPs and the generation of trapping centers formed by the deformation of the surfactant molecules. Our results can be used to control the structure of WO3-based nanomaterials and contribute to the development of next-generation optoelectronic nanodevices of WO3-based nanomaterials.

Effect of Modified Hybrid Nanoparticles on the Properties of Base Oil

Nanomaterials have an excellent potential for improving the rheological and tribological properties of lubricating oil. In this study, oleic acid was used to surface-modify nanoparticles to enhance the dispersion and stability of Nanofluid. The surface modification was conducted for inorganic nanoparticles (NPs) TiO₂ and CuO with oleic acid (OA) surfactant, where oleic acid could render the surface of TiO2-CuO hydrophobic. Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy (SEM) were used to characterize the surface modification of NPs. The main objective of this study was to investigate the influence of adding modified TiO₂-CuO NPs with weight ratio 1:1 on thermal-physical properties such as kinematic viscosity, viscosity index (VI), pour point, and flash point of Iraqi base oil (40 stock) and nano-lubricating oil. The kinematic viscosity of base oil at 40 °C and 100°C increased with high concentrations of modified TiO₂-CuO NPs. The highest value of VI of base oil 40 stock at 0.8 wt. % of modified TiO₂-CuO NPs was 108.5. The results showed that the flashpoint value increased with the increased concentration of modified TiO₂-CuO NPs of base oil 40, where the highest value was 220 °C. The pour point of nano lubricating oil base with 0.8 wt. % of modified TiO₂-CuO NPs showed decreasing from -12 °C to -15 °C of base oil 40.

Microemulsions and nanoemulsions modified with cationic surfactants for improving the solubility and therapeutic efficacy of loaded drug indomethacin

In this work, a noncovalent strategy was successfully used to modify colloidal stability and in vitro and in vivo efficacy of two amphiphilic formulations of the anti-inflammatory drug indomethacin. Namely, nanoemulsions and microemulsions based on oleic acid and nonionic surfactants have been produced and compared. The influence of cationic surfactants cetyltrimethylammonium bromide and its carbamate bearing analogue on the size characteristics, stability and ability to provide prolonged action of loaded drug indomethacin has been evaluated. Adding the positively charged molecules in the surface layer of nanoemulsions and microemulsions has shown the stability increase along with maintaining the size characteristics and homogeneity in time. Moreover, the carbamate modified analogue demonstrated beneficial behavior. Indomethacin loaded in microemulsions and nanoemulsions showed prolonged-release (10%–15% release for 5 h) compared to a free drug (complete release for 5 h). The rate of release of indomethacin from nanoemulsions was slightly higher than from microemulsions and insignificantly decreased with an increase in the concentration of the cationic surfactant. For carbamate surfactant nanocarrier loaded with fluorescence probe Nile Red, the ability to penetrate into the cell was supported by flow cytometry study and visualized by fluorescence microscopy. In vitro tests on anti-inflammatory activity of the systems demonstrated that the blood cell membrane stabilization increased in the case of modified microemulsion. The anti-inflammatory activity of the encapsulated drug was tested in rats using a carrageenan-induced edema model. Nanoemulsions without cationic surfactants appeared more efficient compared to microemulsions. Indomethacin emulsion formulations with carbamate surfactant added showed slower carrageenan-induced edema progression compared to unmodified compositions. Meanwhile, the edema completely disappeared upon treatment with emulsion loaded indomethacin after 4 h in the case of microemulsions versus 5 h in the case of nanoemulsions.

Enhancing AW/EP tribological characteristics of biolubricant synthesized from chemically modified cotton methyl-esters by using nanoparticle as additives

PurposeThe purpose of this study is to improve the tribological characteristics of cotton-biolubricant by adding nanoparticles at extreme pressure (EP) conditions in comparison with commercial lubricant SAE-40.Design/methodology/approachThis research involved the synthesis of cotton-biolubricant by transesterification process and then the addition of nanoparticles in it to improve anti wear (AW)/EP tribological behavior. SAE-40 was studied as a reference commercial lubricant. AW/EP characteristics of all samples were estimated by the four-ball tribo-tester according to the American Society for Testing and Materials D2783 standard.FindingsThe addition of 1-Wt.% TiO2 and Al2O3 with oleic acid surfactant in cotton-biolubricant decreased wear scar diameter effectively and enhanced the lubricity, load-wear-index, weld-load and flash-temperature-parameters. This investigation revealed that cotton-biolubricant with TiO2 nano-particle additive is more effective and will help in developing new efficient biolubricant to replace petroleum-based lubricants.Research limitations/implicationsCotton biolubricant with TiO2 nano-particles appeared as an optimistic solution for the global bio-lubricant market.Originality/valueNo one has not studied the cotton biolubricant with nanoparticles for internal combustion engine applications at high temperature and EP conditions.

Biodegradable Amphoteric Surfactants in Titration-Ultrasound Formulation of Oil-in-Water Nanoemulsions: Rational Design, Development, and Kinetic Stability.

Amphoteric amphiphilic compounds, due to their unique properties, may represent a group of safe and biocompatible surface-active agents for effective colloidal stabilization of nanoformulations. For this reason, the aim of this work was to develop and characterize the oil-in-water nanoemulsions based on two betaine-derived surfactants with high biodegradability, i.e., cocamidopropyl betaine and coco-betaine. In the first step, we investigated ternary phase diagrams of surfactant-oil-water systems containing different weight ratios of surfactant and oil, as the betaine-type surfactant entity (S), linoleic acid, or oleic acid as the oil phase (O), and the aqueous phase (W) using the titration-ultrasound approach. All the received nanoemulsion systems were then characterized upon droplets size (dynamic light scattering), surface charge (electrophoretic light scattering), and morphology (transmission electron as well as atomic force microscopy). Thermal and spinning tests revealed the most stable compositions, which were subjected to further kinetic stability analysis, including turbidimetric evaluation. Finally, the backscattering profiles revealed the most promising candidate with a size <200 nm for potential delivery of active agents in the future cosmetic, pharmaceutical, and biomedical applications.

Application of CO2-Switchable Oleic-Acid-Based Surfactant for Reducing Viscosity of Heavy Oil.

CO2-switchable oligomeric surfactants have good viscosity-reducing properties; however, the complex synthesis of surfactants limits their application. In this study, a CO2-switchable “pseudo”-tetrameric surfactant oleic acid (OA)/cyclic polyamine (cyclen) was prepared by simple mixing and subsequently used to reduce the viscosity of heavy oil. The surface activity of OA/cyclen was explored by a surface tensiometer and a potential for viscosity reduction was revealed. The CO2 switchability of OA/cyclen was investigated by alternately introducing CO2 and N2, and OA/cyclen was confirmed to exhibit a reversible CO2-switching performance. The emulsification and viscosity reduction analyses elucidated that a molar ratio of OA/cyclen of 4:1 formed the “pseudo”-tetrameric surfactants, and the emulsions of water and heavy oil with OA/cyclen have good stability and low viscosity and can be destabilized quickly by introducing CO2. The findings reported in this study reveal that it is feasible to prepare CO2-switchable pseudo-tetrameric surfactants with viscosity-reducing properties by simple mixing, thus providing a pathway for the emulsification and demulsification of heavy oil by using the CO2-switchable “pseudo”-oligomeric surfactants.