Barium Stearate Research Articles

Self-organization of stearic acid salts on the hemispherical surface of the aqueous subphase allows functionalization of matrix-assisted laser desorption/ionization mass spectrometry target plates for on-plate immobilized metal affinity chromatography enrichment

In this work we propose an approach for formation of periodic two-dimensional structures on a solid substrate via self-assembly of stearic acid molecules on an aqueous subphase drop containing metal ions. It was shown that when a saturated solution of stearic acid in n-hexane was applied to the hemispherical surface of an aqueous media containing barium ions, barium stearate monolayer was formed, which spontaneously collapsed during movement from the drop surface to the substrate. By means of infrared and Raman spectroscopy, light and scanning electron microscopy, atomic force microscopy and matrix-assisted laser desorption/ionization mass spectrometry it was proved that a multi-structure of collapsed metal stearate monolayers with a developed surface was formed on the substrate surface. Thin films formed by a single application of stearic acid solution in n-hexane to a drop of aqueous lanthanum nitrate solution were used for selective enrichment of human butyrylcholinesterase adducts with diisopropyl fluorophosphate.

Use of Fatty Acid Metal Salts for Preventing Maillard Reaction-Driven Browning of Lecithins.

We previously reported that fluid soybean lecithin (SL) undergoes heat deterioration by the newly reported pseudo-Maillard rearrangement reaction. To inhibit heat deterioration, SLs were treated with metal silicates, such as magnesium silicate and calcium silicate. When soybean fatty acid was added to SL before treatment with calcium silicate, the color index after heating improved significantly as the acid value increased from 10 to 35 mg KOH/g. To elucidate the role of soybean fatty acid, calcium silicate treatment was carried out by adding several fatty acids to SL. Although saturated fatty acids had no effect on the heat deterioration of SL, unsaturated fatty acids were significantly more effective at inhibiting heat deterioration. Furthermore, for unsaturated fatty acids, it was confirmed that the calcium concentration increased in SL. Based on these results, several fatty acid metal salts were added to confirm whether heat deterioration while heating SL could be inhibited. It was observed that the heat deterioration of SL could be inhibited with fatty acid metal salts, regardless of whether the fatty acids were saturated or unsaturated and whether the metal was monovalent, divalent, or trivalent. Therefore, in this study, we clarified that the heat deterioration of SL could be inhibited by adding fatty acid metal salts to SL. Among sodium stearate, calcium stearate, magnesium stearate, barium stearate, and aluminum tristearate, the divalent fatty acid metal salts had a stronger inhibitory effect on heat deterioration than the monovalent and trivalent salts.

Atomic-scale investigation of the heterogeneous structure and ionic distribution in an ionic liquid using scanning transmission electron microscopy.

Ionic liquids show characteristic properties derived from them being composed of only molecular ions, and have recently been used as solvents for chemical reactions and as electrolytes for electrochemical devices. The liquid structures, i.e., ionic distributions, form when solutes are dissolved in ionic liquids and fundamentally affect the reactions and transfer efficiency in such solutions. In this study, we directly observe the liquid structure in a solution of the long-chain ionic liquid 1-octyl-3-methylimidazolium bromide (C8mim Br) and barium stearate (Ba(C17H35COO)2) using the annular dark-field method of scanning transmission electron microscopy (ADF-STEM). The ADF image shows a 10 nm-scale heterogeneity in the image intensity, which reflects the heterogeneous ionic distribution in the solution. The number density distributions of all the component ions (C8mim+, Br−, Ba2+, and C17H35COO−) were estimated from the ADF image intensity and then visualized. These ionic distribution maps depicted the spatial relationships between the ions at the sub-nanometer scale and revealed that the heterogeneity is largely derived from the large differences in size, charge distributions, and van der Waals interactions.

High performance metal stearates thermal stabilizers for poly vinyl chloride

Low thermal stability of poly vinyl chloride (PVC) is one of the most serious problems that facing its processing. In the present study some single and mixed metal stearate soaps were prepared, characterized and evaluated for their performance in enhancing and imparts the thermal stability of PVC. Accordingly, calcium stearate, barium stearate, zinc stearate and also the mixed metal stearate salt of calcium, zinc and barium were prepared by the double decomposition of sodium stearate and single or mixed metal acetate solutions. The prepared metal stearates were characterized via spectroscopic analysis (FT-IR and XRD) in addition to micro analysis and thermal gravimetric analysis (TGA). The results showed that the prepared metal stearates are good thermal stabilizers for PVC; also the thermal stability of the prepared (Ca/Ba/Zn) stearate was enhanced when melamine, ammonium poly phosphate, magnesium hydroxide and Ca/Zn phosphate are mixed with it.

A Study of the Regularities of the Solid-Phase Synthesis of Metal Stearates

Features of the solid-phase synthesis of metal stearates (calcium, barium, zinc, and silver stearates) on a Bridgman anvil-type device were studied. Factors of the solid-phase reaction between reagents were determined. The activation volumes of the reactions between stearic acid with calcium oxide and silver oxide were determined. The initial rates of the solid-phase synthesis of silver and calcium stearate were calculated. The rates of synthesis of metal stearates in liquid and solid phases were compared. The data showed that metal carboxylates could be synthesized in a solution-less medium.

A facile method of hydrophobic surface modification for acrylonitrile-styrene-acrylate terpolymer based on the out-migration property of metallic soaps

Hydrophobic surface modification is conducted in this study by using additives with long alkyl chains. Several kinds of metallic soaps, such as calcium stearate (CaSt), zinc stearate (ZnSt), magnesium stearate (MgSt) and barium stearate (BaSt) were employed. Polymer matrix is acrylonitrile-styrene-acrylate (ASA) terpolymer due to its wonderful weather resistance property. The surface chemical characterization was studied by Fourier transformed infrared (FTIR) technology and X-ray photoelectron spectroscopy (XPS). Carboxylate (OCO–) indexes of composites in both transmittance and reflection modes were calculated according to FTIR results. As to the ratio of carboxylate index in reflection mode to that in transmittance mode, the sample added with 5 wt% ZnSt shows a higher value of 8.77, and a much higher value of 14.47 for the sample added with 10 wt% ZnSt. The corresponding CC/ CH /CC peak areas of the samples added with 5 wt% or 10 wt% ZnSt are 75.4% and 77.3% respectively, much higher than other samples. This indicates ZnSt is much easier to out-migrate to material surface and therefore is more suitable for hydrophobic surface modification. In particular, the water contact angle of the ASA/ZnSt composite added with 10 wt% ZnSt significantly increased to 127o (40o increase in comparison with pure ASA), successfully converting the surface wettability from hydrophilic to hydrophobic.

Subphase pH induced monolayer to multilayer collapse of fatty acid Salt Langmuir monolayer at lower surface pressure

Abstract Subphase pH induced monolayer to multilayer collapse at very low surface pressure of barium stearate Langmuir monolayer has been confirmed from the surface pressure versus specific molecular area ( π – A ) isotherms, X-ray reflectivity (XRR) and atomic force microscopy (AFM) studies. From the π – A isotherms it is clear that stearic acid molecules form a monolayer on the water surface in the presence of Ba 2+ ions at pH ≈ 5.5 (low) and ≈6.8 (moderate) and remain as a monolayer before collapse pressure ( π c = 55 mN/m). However, at high subphase pH (≈9.5), 2D–3D structural transition starts to occur from the very low surface pressure as indicated by the π – A isotherm and is verified by both XRR and AFM as the barium stearate multilayer structure deposits in the single up stroke of hydrophilic Si substrate at π = 25 mN/m. Subphase pH induced monolayer to multilayer formation at such lower surface pressure is unusual. Fourier transform infrared spectroscopy results confirm that the formation of bidentate chelate coordination in the metal containing headgroup is the reason for such monolayer to multilayer transition. Relatively longer chain fatty acid molecules like arachidic and behenic acids do not show such type of monolayer collapse.

Study of some Complex Organic Materials Characteristics in Thin Films

Studies were carried out in order to investigate the sensitivity of some thin films, to ultraviolet light, based on barium stearate and carbon nanotubes structures. A three – five monolayers structures were developed using the Langmuir – Blodgett technique onto ceramic substrate. Obtained Langmuir – Blodgett complex thin films shows sensitivity to ultra violet light radiation, taking into consideration the presence of carbon nanotubes that facilitates the charge carriers transport. Also the investigations performed, revealed the properties of carbon nanotubes and point out the fine chemistry of these materials. Based on this premise we proceed to investigate and characterize the photo – electrical behavior of the obtained structures.

Amphiphilic Molecules of Nb18: Synthesis, Langmuir-Blodgett Films Construction and Applications in Electro-Catalysts

A new type of Nile blue (Nb) derivative molecules terminated with long-chain alkyl (termed as Nb18) has been synthesized from precursors of barium stearate and 3-amino-7-(diethylamino)-1,2-benzophenoxazin sulfate. Optical characterizations including UV-Vis absorption, fluorescence emission, excitation spectra and the infrared spectroscopy reveal a blueshift in the band emission of Nb18 as compared to the Nb molecule, and this shift was found to be reasoned by incorporation of long-chain alkyl groups and replacement of SO42−. The amphiphilic Nb18 molecules were found to form stable Langmuir monolayers over aqueous solutions, and this allows one to study the kinetics of Nb18 formation by means of surficial chemistry. The synthetic reaction was demonstrated to have first-order kinetics with a rate constant of ∼0.0033 s−1. Using different techniques (Langmuir-Blodgett and Langmuir-Schaefer) monolayers of Nb18 were deposited on an electrode where the amphiphilic molecules were differently oriented. Investigation of these films undertaken to confirm some of the previous electrochemical observations indicated that the electro-catalytic activity stems from the cationic rings of aromatic oxazine regarding to the oxidation of dihydronicotinamide adenine dinucleotide (NADH).

Effect of Barium Stearate on the Thermal Stability of Polyvinyl Chloride

Thermal degradation reaction kinetics of PVC stabilized by barium stearate were studied by means of the non-isothermal weight-loss technique under a nitrogen atmosphere. The results show that the lowest decomposition temperature is greater than 203.6°C and 217.2°C in the conversion rate of 5% and 10% respectively. When the heating rate β is 10°C/min, at 200°C and 225°C the remaining mass from the sample with barium stearate was 99.1% and 95.3%, respectively. The thermal decomposition process occurred in three stages, the results calculated by various methods show that the average apparent activation energy in first, second and third phase is 79.88kJ/mol, 89.37kJ/mol and 187.34kJ/mol respectively. In the initial reaction ( α<18%), as heating rate is 20°C/min, the decomposition reaction is controlled by the (A1.5) mechanism.

Effects of dibutyltin dilaurate and epoxidized soya bean oil on the thermal stability of chlorinated natural rubber from latex

AbstractThe effects of dibutyltin dilaurate (DBTL) and epoxidized soya bean oil (EBO) on the dehydrochlorination reaction of chlorinated natural rubber (CNR) from latex were studied by the measurement of the HCl evolving rate during the thermal degradation of CNR and by the determination of the amounts of cyclic conjugated dienes that formed on the CNR molecular chains. During the early stage of the thermal degradation of CNR at 150°C, HCl was eliminated, and the cyclic conjugated dienes formed on the CNR molecular chains. Under the effects of DBTL and EBO, the HCl evolving rates during the early stage of the thermal degradation of CNR were reduced, whereas the amounts of cyclic conjugated dienes formed on the CNR molecular chains were increased. Under the effects of mixtures from the compounding of DBTL with barium stearate or 2,2′‐methylene‐bis(4‐methyl‐6‐tert‐butyl‐phenol) as well as the compounding of EBO with 2,2′‐methylene‐bis(4‐methyl‐6‐tert‐butyl‐phenol), not only the HCl evolving rate from CNR but also the formation of cyclic conjugated dienes decreased, and this indicated that the compounded mixtures had synergistic functions against the thermal degradation of CNR. However, the mixture from the compounding of EBO with barium stearate had no synergistic effect on increasing the thermal stability of CNR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1986–1991, 2006

Effects of stearates on the thermal stability of chlorinated natural rubber from latex

AbstractThe effects of stearates on the dehydrochlorination (DHC) reaction of chlorinated natural rubber (CNR) from latex were studied by the measurement of the HCl evolving rate during the early stage of the thermal degradation of CNR and by the determination of the amounts of cyclic conjugated dienes formed on the CNR molecular chains. During the early stage of the thermal degradation of CNR at 150°C, HCl was eliminated from the CNR molecular chains, and the cyclic conjugated dienes were formed on the CNR molecular chains. Under the effects of barium stearate, lead stearate, cadmium stearate, and calcium stearate, the HCl evolving rates of CNR were reduced, whereas the amounts of cyclic conjugated dienes that formed on the CNR molecular chains were increased. When zinc stearate was added, because of the formation of ZnCl2, which was an active catalyst of the DHC reaction of CNR, both the HCl evolving rate from CNR and the formation of cyclic conjugated dienes were increased. The results indicate that the addition of stearates can reduce the thermal stability of CNR. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1981–1985, 2006

Reusability of the Cu/Ni-based colloidal catalysts stabilized by carboxylates of alkali-earth metals for the one-step amination of dodecyl alcohol and dimethylamine

The Cu/Ni-based colloidal catalyst, stabilized by barium stearate (Cu:Ni:Ba mole ratio 5:1:1; particle size 1–5 nm), for the one-step amination of dodecyl alcohol and dimethylamine to N, N-dimethyldodecylamine at Cu concentration ranges of 300–1000 ppm at 200–210 °C, could be recovered by distillation and could be reused several times without a decrease in the activity. The activity of the concentrated activated colloidal catalysts for the amination reaction was not decreased for a month. These observations demonstrated that the reusability and stability of the Cu/Ni-based colloidal catalysts were enough for the commercial operation, which opposed to the claim that a colloidal catalyst cannot be recovered and reused. The Cu/Ni/Ba colloidal catalyst is the first example of a metallic colloid applied for the amination reaction.

Development of CO-resistive catalysts for the one-step amination of dodecyl alcohol to N, N-dimethyldodecylamine, and effect of carbon monoxide on activity of Cu/Ni-based catalysts

Dodecyl aldehyde is the intermediate in the one-step amination of dodecyl alcohol and dimethylamine (HNMe 2) to the corresponding tertiary amine, N, N-dimethyldodecylamine (RNMe 2). Carbon monoxide (CO) generated by the decarbonylation of dodecyl aldehyde, significantly poisons the Cu/Ni-based colloidal catalysts stabilized by barium stearate (Cu/Ni/Ba). Therefore, the prevention of CO generation or removal of CO from the reaction system was required to maintain the catalytic activity. A copper-based CO absorber was effective for removing CO, but the methanation of CO was not effective because of a significant decrease in activity of the Cu/Ni/Ba colloidal catalyst and a significant transalkylation of HNMe 2. The incorporation of a small amount of triphenylphosphite (P(OPh) 3) with the Cu/Ni/Ba colloidal catalyst (Cu:Ni:Ba:P(OPh) 3 mole ratio = 5:1:1:0.16) caused a significant reduction in CO poisoning. Water was also a catalyst poison for the Cu/Ni/Ba colloidal catalyst, and cupric hydroxide significantly decreased the catalytic activity.

Amination of alcohols, using Cu/Ni-based colloidal catalyst, for consecutive reaction system

Animation of dodecyl alcohol and monomethylamine (MMA, di-functional) using Cu/Ni-based colloidal catalyst stabilized by barium stearate, and its kinetic study were performed to effectively synthesize didodecylmethylamine (DDMA). For the initial 3–4 h when MMA/dodecyl alcohol mole ratio was less than 1, the amination reaction proceeded very fast (72 mole-alcohol h-1 mole-Cu at 200 °) by zero-order kinetics to directly produce DDMA (85%), with complete consumption of MMA, without liberation of the intermediate, momomethyldodecylamine (MMDA) at all. Then, immediately after the mole ratio exceeded 1, the amination proceeded very slowly (3.4 mole-alcohol h-1 mole-Cu) by consecutive mechanism (second order) with liberation of MMDA. Aldolization of dodecyl aldehyde, formed by dehydrogenation of dodecyl alcohol, was found to be catalyzed by methylamines. Maintaining the zero-order kinetics by continuous control of MMA/alcohol mole ratio at less than 1 through out the amination is essential to obtain a highest DDMA yield by preventing the unwanted aldolization and transalkylation of MMA leading to various byproducts. Catalytic activity of the colloidal catalyst was sevenfold active than that of corresponding solid ones. Amination of 1,6-hexanediol and dimethylamine, using the colloidal catalyst and liquid paraffin as a solvent, was proceeded by consecutive mechanism to form N,N,N′,N′-tetramethyl-l,6-hexamethylenediamine with an yield of 80%.

An approach for fabrication of junctions with Langmuir–Blodgett films incorporated between molecular electrodes

Langmuir–Blodgett (LB) assemblies composed of monolayers of different compounds alternating in a predetermined sequence are potential candidates for development in the field of nanoelectronics. However, their poor mechanical stability restricts the possibility of fabrication of interconnected electronic elements because LB films can be easily destroyed during the deposition of metal electrodes. In this work, we present a technique for the fabrication of junctions for the electrical characterization of one-component LB films and LB assemblies enclosed between thin molecular electrodes. The molecular electrodes are produced using LB films of a charge-transfer salt. Such an application of these films became possible due to considerable improvements in their conductivity, quality of deposition and stability in comparison with the properties of films of similar compositions studied previously. Lateral patterning of electrodes is carried out by the irradiation of conductive films with an electron beam, which results in the loss of their conductivity. In this way, it is possible to prepare the samples for electrical investigations without any damage to incorporated LB films. The LB films of barium stearate, polycyanoacrylate, mixture of surfactant donor and acceptor, porphyrins, as well as the LB assemblies composed of thin layers of these compounds deposited in various sequences were enclosed between the molecular electrodes and studied. Probable conduction mechanisms are discussed on the basis of obtained data.

A 212Pb generator based on a 228Th source

A two-compartment 212Pb generator has been constructed and characterized physically and chemically. It is based on transport by airflow of gaseous 220Rn emanating from thin layers of [228Th]barium stearate. 220Rn is collected in a glass bubbler by extraction into an organic solvent and solidified at temperatures below –72°C. Tracer studies show that the decay product 212Pb can be recovered with approximately 70% yield. It is suggested that this generator design could accommodate therapeutic levels of 212Pb/228Th.

Generation of lead-212 and radioimmunoconjugates for use in cancer therapy and the ‘emanating power’ of stearates

The emanating power of stearates (i.e. their ability to release radioactive gas generated within them) combined with the diffusivity of this gas, permit the spatial separation of Pb-212 from its longer lived and thus undesirable parents. A generator for the α-particle emitter Pb-212 is described. It features two chambers separated by a porous septum. A small chamber is loaded with Th-228 carried by barium stearate and a large one contains a powder, which retains recoiling products of radon. The Pb-212 could be harvested daily for therapeutic use with an initial efficacy of over 60% but radiation damage to the stearate reduced its emanating power after about 3 month of continuos operation. The generator, described here, allows for harvesting ultrapure short-lived products and relatively simple workup procedures. An important assumption concerning the feasability of a Pb-212 complexed radioimmunoconjugate is that the entrapped Pb-212 can survive the Bi-212 recoil and the 2.24 MEV β-emission during the Pb–Bi transition. To test this we produced a monoclonal antibody modified organic chealate intermediate to which the generator produced Pb-212 has been complexed. We were able to show selective tumor cell cytotoxicity and stability of the conjugate under ordinary cell culture conditions.

Structure of Barium Stearate Films at the Air/Water Interface Investigated by Polarization Modulation Infrared Spectroscopy and π−A Isotherms

Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and π−A isotherms were applied to investigate in situ the fragile stearic acid/Ba2+ (BaSt) system on the aqueous BaCl2 subphase in a Langmuir trough. The spectra were recorded at 294−274 K, pH = 9.5 and 6.3, and 4 cm-1 resolution with excellent signal-to-noise ratios. At pH = 6.3 the stearic acid was not totally deprotonated and no genuine unit cells were detected. The mixed COOH/COO- monolayer had CH2 antisymmetric (νas(CH2)) and symmetric (νs(CH2)) bands at 2917 and 2851 cm-1, respectively, indicating a predominantly trans zigzag chain conformation. At pH = 9.5 the stearic acid was totally deprotonated after spreading and formed a monolayer with ionic interaction between the COO- group and the subphase Ba2+ ion. Later the monolayer spontaneously reorganized into a three-dimensional structure, where the COO group and the barium atom formed a chelating bidentate coordination. This reorganization took 11 min to complete at 294 K...

Thermal Stability of Stearic AcidBarium Stearate Langmuir−Blodgett Monolayers on Plasma-Oxidized Silicon Substrate Probed by Atomic Force Microscopy

Mixed stearic acid−barium stearate Langmuir−Blodgett (LB) monolayers have been deposited on oxygen plasma oxidized silicon substrate. Atomic force microscope (AFM) has been used in order to obtain quantitative information about the coverage of the substrate after annealing at temperatures ranging from room temperature to 120 °C. These measurements allowed us to measure the rate constant K of the desorption process. Data showed that at low temperatures the formation of new holes (nucleation) and hole broadening (growth) have comparable rates, while at higher temperature nucleation has a catastrophic effect on the coverage. These observations suggest that different mechanisms are in action at temperatures above and below 55 °C, the hydration layer present between substrate and organic film probably playing a role in both mechanisms. Data are discussed in terms of both activated state theory and dynamical model.