No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Interaction of the Acid Soap of Triethanolamine Stearate and Stearic Acid with Water
Abstract
Stearic acid and triethanolamine (TEA) in a molar ratio of 2:1 were mixed in aqueous solution at 80 degrees C and subsequently cooled to ambient temperature. The structural evolution of the resultant sample during storage was characterized by using light microscopy, Cryo-SEM, differential scanning calorimetery, pH, infrared spectroscopy, elemental analysis, and simultaneous small and wide-angle X-ray diffraction. It was found that a lamellar liquid crystalline phase was formed when stearic acid and TEA solution were mixed at 80 degrees C and multilamellar spheres of a few microns diameter were formed initially after cooling. A hydrolysis reaction (i.e., the reverse reaction of neutralization between stearic acid and TEA) occurred thereafter that caused the breakdown of the lamellar gel phase and the formation of platelet stearic acid crystals. Three polymorphs of stearic acid (defined following previous work as the A, C, and E forms) were formed as the result of hydrolysis reaction, which gave rise to a strong optically pearlescent appearance.
... It is the reaction of an undissociated weak base molecule present in solution with a weak acid molecule that is a component of the model skin sebum, resulting in the formation of an amine soap. According to observations made by Zhu et al. on similar soap composition i.e., TEA stearate, it should be assumed that the resulting amine soap slowly hydrolyses over time [23]. However, this process is slow and lengthy, thus the changes were observed after several dozen hours. ...
... In the course of research by Zhu et al., it was shown that stearic acid formed during hydrolysis, which is a weak acid insoluble in water, was deposited in the form of plaques, while the weak base remained in the aqueous solution. Therefore, the presence of stearic acid in the form of dispersed plaques should not have a significant influence on changes in the pH value of the solution above the sebum [23]. Our tests were carried out in a much shorter period of time, not exceeding 4 h, and also in stable environmental conditions, assuming the hydrolysis process to an insignificant degree. ...
... Based on these theoretical considerations, it can be assumed that the hydrolysis of the resulting soap does not occur or takes place to a very small extent without affecting the pH value of the solution above the layer of model skin sebum. However, Zhu et al. demonstrated the hydrolysis and decay of soap by conducting a series of studies on the behavior of acid soap triethanolamine stearate under varied temperature conditions and in a long observation period [23]. Researchers prepared TEA stearate at a temperature of 80 • C, and then the formed soap was cooled to ambient temperature and observed for a period of 90 days. ...
Alcoholamines are widely used as auxiliary substances in various topical preparations. Their impact on the components of skin sebum allows them to be used in preparations that cleanse the skin of sebum in hair follicles. We measured the effects of various concentrations of aqueous solutions of AMPD (2-amino-2-methyl-1,3-propanediol) on model skin sebum. The volume of reacted sebum was calculated using two methods: optical assessment of the interaction of alcoholamines with the components of model skin sebum and determination of the reacted volume of model skin sebum based on the measurements of changes in the pH of the AMPD solutions. Both methods showed that the most favorable AMPD concentration for model sebum penetration was approximately 1–2%. Lower values of alcoholamine caused premature exhaustion from the solution. Excessively high concentrations resulted in the formation of a dense layer of products hindering effective skin cleansing.
... Goddard reported that equimolar compounds are formed in a system containing potassium soap-fatty acid 11 . Skoda confirmed the existence of 5:1, 5:2, 3:2, 1:1 and 2:3 sodium stearate/stearic acid in the binary system of sodium stearate-stearic acid 12 , while Zhu reported the phase diagram of triethanolamine stearate-stearic acid and confirmed the existence of only one acid soap complex at a 1:2 ratio 13,14 . ...
... Water was deionized using an Organo FW-10 system. Potassium myristate KC 14 and potassium hydrogen myristate used for the X-ray diffraction experiments were prepared by dissolving mixtures containing stoichiometric amounts of HC 14 and KOH in ethanol at elevated temperatures. After evaporation of the solvent, the precipitate was dried until weight was constant. ...
... Water was deionized using an Organo FW-10 system. Potassium myristate KC 14 and potassium hydrogen myristate used for the X-ray diffraction experiments were prepared by dissolving mixtures containing stoichiometric amounts of HC 14 and KOH in ethanol at elevated temperatures. After evaporation of the solvent, the precipitate was dried until weight was constant. ...
Fatty acids, fatty acid potassium soaps, glycerol and water are essential ingredients in the production of stable cream soaps. In this study, the behavior of these components in solution was investigated to elucidate the stability conditions and mechanism of cream soaps. It was determined that the cream soaps were a dispersion of 1:1 acid soap (1:1 molar ratio of potassium soap/fatty acid) crystals in the lamellar gel phase, which has confirmed from the phase behavior diagrams and small angle X-ray scattering data. Glycerol was crucial ingredient in the formation of the lamellar gel phase. The cleansing process of the cream soaps was also evaluated using the same diagrams. The structure of the continuous phase in cream soaps changed from lamellar gel to a micellar aqueous solution upon the addition of water. This structural change during the washing process is important in producing the foaming activity of acid soaps to wash away dirt or excess fats from the skin surface.
... For the potential applications of AS complexes, the study on the fatty acid-soap phase behaviors in solvents has becoming much attracted. Although the solubility of long chain fatty acids is low, rich mesophases could still be mapped by their soaps and fatty acid-soap in water or ionic liquids [10,[12][13][14][15][16][17][18][19]. It was reported that the saturated (10-18 carbons) 1: 1 alkaline fatty acid-soap systems could spontaneously form liquid crystalline aggregates in water, including the inverted hexagonal and lamellar structures [16][17][18]. ...
... It was reported that the saturated (10-18 carbons) 1: 1 alkaline fatty acid-soap systems could spontaneously form liquid crystalline aggregates in water, including the inverted hexagonal and lamellar structures [16][17][18]. Zhu et al. found a lamellar gel phase in stearic acid-triethanolamine stearate AS complex solution at 80 • C, which would be collapsed after cooling due to the hydrolysis reaction [13]. The hydrogels can also be formed from AS complex with amine, which has been applied as a template for metal nanoparticle preparation [14]. ...
... It is then interesting to know how such an acid-soap complex behaves in aqueous solution. At high temperatures, it was reported that the crystalline ammonium AS complex could be transformed into a hydrated lamellar liquid crystal [13]. However, constructing their lyotropic phases at room temperature is challenging. ...
... It is possible to create stearic acid platelets by melting pure stearic acid, dissolving it in water, and allowing it to crystallize. 28 However, this process is tedious and requires precise control of the temperature during the crystallization process, as well as a careful selection of complementary surfactants to prevent the crystals from clumping. Luckily, the cosmetics industry has already solved these problems and stearic acid platelets, such as those shown in Fig. 2, can be easily extracted from common shaving cream. ...
... This sets up conditions similar to the experiments of Zhu et al., who showed that as an aqueous solution of stearic acid and triethanolamine cools, flat stearic acid crystals form through a nucleation and ripening process. 28 In order to confirm that the solids in our fluid are made of stearic acid, we compared their nuclear magnetic resonance (NMR) spectrum to publicly available reference spectra for stearic acid and found them in good agreement. Interested readers will find the physicochemical and crystallographic properties of these crystals in the review paper by Sato. ...
In rheoscopic flow visualization, the working fluid is seeded with small reflective flakes that align preferentially in the flow due to their anisotropy. This leads to directed light scattering, which can be exploited to distinguish qualitatively different regions of the flow. For the past four decades, the gold standard in rheoscopic flow visualization has been Kalliroscope, a commercial product consisting of crystalline guanine particles. Recently, however, worldwide production of crystalline guanine has dropped precipitously, leading the Kalliroscope Corporation to halt production in 2014. Here, we present a short survey of alternative rheoscopic flow visualization techniques and introduce an inexpensive rheoscopic fluid based on stearic acid crystals extracted from shaving cream, which has a performance similar to, and in certain respects superior to, Kalliroscope.
... The evaluation of the melting profile of ILs and their mixtures with other solvents requires an accurate study of the solid−liquid equilibrium (SLE). 212,214 The method of differential scanning calorimetry (DSC) has been used by many authors for the study of SLE of pure ILs, 24,215,216 IL-based products, 217−220 and IL mixtures, 26,206 being the most efficient method for determination of transition temperatures. Other methods, such as infrared spectroscopy, first reported by Pudney et al. 213 on the characterization of stearate-based ILs mixtures, and microscopy have been also applied. ...
... 158 Determining the melting temperature profile for mixtures of ILs and other compounds could be necessary for designing products and solid-phase extractions. Mixtures with tris(2-hydroxy ethyl)ammonium salts and fatty acids, for example, have shown an interesting liquid crystalline profile that is useful in the case of formulating soaps 24,212,213 or design fatty acid separation processes in liquid media. The use of N,N′,N″,N‴-hexadecyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([C 16 tma][NTf 2 ]) is another example in this case. ...
Ionic liquids (ILs) have been extensively used in many researches and industry fields, including chemical and pharmaceutical applications. Nevertheless, during past years, some works revealed that those green solvents in fact could present certain toxicity levels. This is the reason why some biocompounds from natural sources, such as choline, amino acids, and organic acids, for synthesis of ILs have showed to be an alternative. It means, there are evidences that ILs with low or non-toxic effects could be synthesized, possibly overcoming the major drawback of using them in the food industry. Applications of this third generation ILs, or even the most common ILs, in food processes are scarce and main focused on extraction processes and chemical analysis methods. These works have proven that, considering the physical properties of ILs of interest for food industry, such as melting profile, solubility and viscoelasticity, high biocompatibility, when compared to those commonly used, it is an alternative aspect for using them for the design of food products and processes. In this context, the present review provides an overview on applications of ILs in food industry reported up to date in the literature, disclosing on their synthesis with natural biocompounds. Also, it proposes new applications in food and bioproducts industries, based on the main trends of the recent literature.
... In the current work, the DoE cream formulation was structured by a viscous lamellar gel network phase formed by, apart from stearic acid and cetyl alcohol, an interaction of triethanolamine stearate and different amounts of glycerol monostearate. Triethanolamine stearate is an anionic surfactant contributing to the lamellar phase arrangement with an extensive swelling [1,44,45]. Glycerol monostearate is a fatty amphiphile nonionic ester of glycerol alcohol and stearic acid widely used in pharmaceutical products as thickener, emulsifier, and emollient [46,47]. Due to the similar molecular geometry of triethanolamine stearate and glycerol monostearate, when blended, those molecules are closely packed together contributing to a firm and strength gel network formation [48]. ...
This work aims at providing the assumptions to assist the sustainable development of cream formulations. Specifically, it envisions to rationalize and predict the effect of formulation and process variability on a 1% hydrocortisone cream quality profile, interplaying microstructure properties with product performance and stability. This tripartite analysis was supported by a Quality by Design approach, considering a three-factor, three-level Box–Behnken design. Critical material attributes and process parameters were identified from a failure mode, effects, and criticality analysis. The impact of glycerol monostearate amount, isopropyl myristate amount, and homogenization rate on relevant quality attributes was estimated crosswise. The significant variability in product droplet size, viscosity, thixotropic behavior, and viscoelastic properties demonstrated a noteworthy influence on hydrocortisone release profile (112±2-196±7 μg/cm2/√h) and permeation behavior (0.16±0.03-0.97±0.08 μg/cm2/h), and on the assay, instability index and creaming rate, with values ranging from 81.9 to 120.5%, 0.031±0.012 to 0.28±0.13 and from 0.009±0.000 to 0.38±0.07 μm/s, respectively. The release patterns were not straightforwardly correlated with the permeation behavior. Monitoring the microstructural parameters, through the balanced adjustment of formulation and process variables, is herein highlighted as the key enabler to predict cream performance and stability. Finally, based on quality targets and response constraints, optimal working conditions were successfully attained through the establishment of a design space.
... The neutralization reaction of TEA stearate occurs when stearic acid and TEA are mixed together at a temperature above the stearic acid melting point. The formed product turns into TEA stearate salt, otherwise known as TEA soap [14]. Glycerin was used as a humectant that works to moisturize the skin. ...
Cream preparation was made by mixing oil phase and water phase, then active ingredients namely the combination of TiO2 and ZnO nanoparticles were added using capping agent of Hibiscus rosa sinensis leaf extract (F3). This cream was then used as the main cream. Comparative creams were also made using formulas of F0, F1, F2, F4 and F5. The effectiveness test for cream preparations was done in vitro by testing the absorbance using UV-Vis spectrophotometer. Determination of SPF values was calculated by the Mansur equation. After 28-day storage, the results showed that the pH values and cream viscosity were within the range of values corresponding to the Indonesian National Standard for sunscreen product. The results of UV detection showed that F3 cream made from combination of TiO2 and ZnO nanoparticles as active ingredients using capping agent of Hibiscus rosa sinensis leaf extract has the highest SPF value of 6,927. This value has met the minimum value of the FDA (Food Drug Association).
... Lower acidic pH values (2.5-4.0) were found in formulations F2, F4, F6, and F8 which contained Carbopol 940 (Rowe, Sheskey, & Weller, 2003). The presence of TEA stearate resulted in the highest pH values in formulations F3 (7.57) and F7 (7.55) (Zhu et al., 2007). According to Schulman and Cockbain (1940b), emulsifying agents with the same fatty acid composition or the same hydrocarbon chain length provide emulsions with higher stability. ...
Grape seed extract (GSE) contains a high content of polyphenols that prevent the generation of reactive oxygen species
which suggests an anti-aging action. The aims of this study were to investigate the antioxidant effects of GSE, ultraviolet (UV)
and visible spectrums, and in vitro sunscreen efficacy. The results showed that GSE possessed DPPH free radical scavenging
capacity at an IC50 of 33.17±1.87 μg/mL and ferric reducing power of 1 mg/mL. GSE was equivalent to 4.17±0.23 mM vitamin C
and 0.73±0.04 mM Trolox. Moreover, 3% and 5% w/w GSE absorbed broad UV and blue light spectra to a sufficient extent. The
sun protection factor (SPF) and persistent pigment darkening (PPD) increased to 5 units and 1 unit, respectively, after addition of
3% GSE to an over-the-counter brand product. In conclusion, GSE possessed antioxidant activity and boosted the SPF/PPD value
of sunscreen product. Therefore, GSE can be a value-added component to sunscreen products.
... The key ingredient in any rheoscopic fluid is the anisotropic seeding particles and it is possible to create stearic acid platelets by melting pure stearic and allowing it to crystallize from an aqueous solution. 25 However, this process is tedious and requires precise control of the temperature during the crystallization process, as well as a careful selection of complementary surfactants to prevent the crystals from clumping. Luckily, the cosmetics industry has already solved these problems and stearic acid platelets, such as those shown in Fig. 1, can be easily extracted from common shaving cream. ...
In rheoscopic flow visualization, the working fluid is seeded with small reflective flakes that align preferentially in the flow due to their anisotropy. This leads to directed light scattering, which can be exploited to distinguish qualitatively different regions of the flow. For the past four decades, the gold standard in rheoscopic flow visualization has been Kalliroscope, a commercial product consisting of crystalline guanine particles. Recently, however, worldwide production of crystalline guanine has dropped precipitously, leading the Kalliroscope Corporation to halt production in 2014. Here, we present a short survey of alternative rheoscopic flow visualization techniques and introduce an inexpensive rheoscopic fluid based on stearic acid crystals extracted from shaving cream, which has a performance similar to, and in certain respects superior to, Kalliroscope.
... The alkanolammonium ILs are protic ionic liquids with a huge potential in a variety of industrial fields. Alkanolamines soaps, PILs formed by the reaction between an alkanolammonium and fatty acids, are currently used in the formulation of industrial and handcleaners, cosmetic creams, aerosols and shave foams due to their emulsifier, and detergent ability in oil-in-water emulsions [11][12][13][14]. The monoethanolamine oleate is widely used in the pharmaceutical industry as sclerosant agent [15][16][17][18]. ...
The alkanolammonium ILs are protic ionic liquids (PILs) with huge potential in a variety of industrial fields. Among other advantages, these PILs have low cost of preparation, simple synthesis and purification methodologies and low toxicity. This study aims at obtaining significant data on the fundamental thermophysical properties of hydroxyethylammonium-based PILs with carboxylate anions. The density was measured within the temperature and pressure intervals (298.15 to 343.15) K and (0.1 to 35.0) MPa for 2-hydroxyethylammonium propionate, [2-HEA][Pr]. The speed of sound was determined in the ranges (303.15 to 353.15) K and (0.1 to 20.0) MPa for the same substance. The estimated combined standard uncertainties are ±0.45 kg⋅m⁻³ for density and ±1.6 m⋅s⁻¹ for speed of sound. The experimental pVT data were fitted using the Goharshadi–Morsali–Abbaspour equation of state (GMA EoS) with average relative absolute deviation (%AARD) of 0.03%. Thermomechanical coefficients as the thermal expansivity, isothermal compressibility, and internal pressure, were calculated using GMA EoS with the internal pressure being further compared with calculated values of cohesive energy density. The experimental pVT data were further successfully described by the predictive methods of Gardas and Coutinho and Paduszyńki and Domańska.
... On the FT-IR spectra, we focused on the characteristic bands of COO À (deprotonated form) and COOH (protonated form). The peaks at 1565 cm À1 and 1700 cm À1 correspond to the COO À and COOH, respectively [30]. For R < 0.8, these two peaks were observed for the two systems (Fig. 7a,b). ...
... Their results mean that octadecyltrim e t h y l a m m o n i u m c h l o r i d e a n d d i p a l m i t o y l phosphatidylcholine provide hydrated crystals and the stable gel phase, whereas potassium stearate gives an anhydrated crystal and the unstable gel phase. Zhu et al. carried out the structural studies in the triethanolamine acid soap-water system 13 . The acid soap including water gives a lamellar liquid crystalline one phase at 80 . ...
Fatty acids, fatty acid potassium soaps, polyols and water are essential ingredients for producing stable cream soaps. The solution behavior of the above four components system has been studied to elucidate the effect of four sorts of polyols (glycerol, 1,3-butylene glycol, polyethylene glycol 400 and dipropylene glycol) on the stability of cream soaps. It has been revealed that the lamellar liquid crystalline one-phase converted to a two-phase of a lamellar phase and an isotropic aqueous solution by the addition of a few percent of 1,3-butylene glycol, polyethylene glycol 400 and dipropylene glycol, whereas the lamellar one-phase was remained by about 50 wt% of glycerol in the aqueous solution. The X-ray data at room temperature showed that the existence of 1:1 acid soap (1:1 mole ratio of potassium soap/fatty acid) crystals in the 1,3-butylene glycol, polyethylene glycol 400 and dipropylene glycol systems, whereas that the coexistence of 1:1 acid soap crystal and a lamellar gel phase (swelled lamellar gel structure) in the glycerol system. The phase transition peaks from coagel to gel (Tgel) and from gel to liquid state (Tc) were appeared in the above four polyol systems by DSC measurements. It was confirmed from the combined data of SAXS and DSC that the existence of anhydrous 1:1 acid soap gels (or with small amount of bound water) in the all polyol systems, whereas the coexistence of the anhydrate gel and the swelled gel with a lot of intermediate water in the only glycerol system. This swelled gel structure would be contributed to stabilize the dispersed anhydrate acid soap crystals in cream soaps.
... era de esperarse, puesto que se está incrementando la lipofilicidad del sistema , haciendo que el anfifilo se oriente más rápido hacia la formación de la fase media. En este sistema, a concentraciones entre 0,7-0,8% m/m de ácido, se observa macroscópicamente la formación de una fase turbia con aspecto de gel (cristal líquido) (Shrestha et al., 2007:262; Duerr-Auster et al., 2007:12827; Zhu et al., 2007 de la cadena de la fase orgánica el anfifilo tiende a formar más rápido la fase media, razón por la cual en el diagrama no se muestra la zona WII. Por otra parte, en este sistema a concentraciones de 1,6% m/m de ácido, aparece una fase gelificada que co-existe entre la fase media y la fase acuosa. ...
The gel-like phase constructed by fatty acid compounds is a kind of fascinating soft matters but its structural characteristics have not been fully understood. This work has investigated the crystalline structures and formation mechanism of gel-like phase containing potassium stearate (KS), stearic acid (SA), and water at 80% neutralization degree. The crystalline fibers are observed in the gel-like samples of KS-SA-water on the polarized optical microscopy. X-ray diffraction measurement demonstrates that there are two isolate types of lamellar crystallites of KS and KS-SA complexes instead of the mixed crystallites in KS-SA-water samples. While KS crystallites have shorter Bragg spacing and tilted angle than the crystallites of KS-SA complexes, it is found that the solvent of water does not penetrate in the interlayer of two kinds of crystallites. The dynamic rheology measurement suggests the strong elasticity of KS-SA-water samples, which indicates the network structure formed by the lamellar crystalline fibers entrapping water. The addition of glycerol does not affect the crystalline structures of KS-SA-water samples, but significantly increase the values of storage modulus and melting enthalpy. This result suggests that the added glycerol can promote the strength of the hydrogen bonding between the solvent and crystalline fibers in the network structure of KS-SA-water samples. These findings provide new insights to the structural properties of gel-like phase of fatty acid compounds, which are importantly helpful for controlling their structure and functions.
Ionic liquid crystals (ILCs) derived from functional compounds obtained from natural sources, such as fatty acids (FAs), are promising compounds due to their sustainable appeal, low cost, and nutritional value. To expand the application of naturally-derived ILCs, this work discloses the use of the oligomeric approach to tune the LC and melting profiles of ILCs derived from FAs (stearic and oleic acids) and choline by mixing them to their parent FA. The oligomeric systems were investigated through the characterization of the solid-[liquid crystal]-liquid (S-LC-L) thermodynamic equilibrium. S-LC transitions were modelled using Margules and Margules-UNIFAC approaches, with the former presenting better results. The systems presented melting profiles similar to eutectic mixtures with a nonideal behavior and formation of solid solutions. The reduction of the melting point and the LC temperature window was related to the concentration and presence of unsaturation in the molecular structure of the components. The LC mesophases were formed at a wide temperature and FA concentration range. Oleic acid-based system presented lower melting points and a broader LC temperature domain with possibly two types of mesophases (lamellar and inverted hexagonal). Therefore, the oligomeric approach promoted the tunability of the LC and melting profiles of naturally-derived ILCs, which might expand their industrial applicability as lubricants, solvents and reaction media for low or high temperature processes, or as structuring agents (e.g. melting profile modifier) for the design of natural-based products.
Hexagonal liquid crystals and supramolecular polymers from meglumine-based supra-amphiphiles were developed as drug delivery systems to be applied on the skin. The influence of fatty acid unsaturation on the structure and mechanical properties was evaluated. Moreover, we have investigated the system biocompatibility and how the type of water could influence its bioadhesive properties. Meglumine-oleic acid (MEG-OA) was arranged as hexagonal liquid crystals at 30-70 wt% water content, probably due to its curvature and increased water solubility. Meglumine-stearic acid (MEG-SA) at 10-80 wt% water content self-assembled as a lamellar polymeric network, which can be explained by the low mobility of MEG-SA in water due to hydrophobic interactions between fatty acid chains and H-bonds between meglumine and water molecules. Both systems have shown suitable mechanical parameters and biocompatibility, making them potential candidates to encapsulate therapeutic molecules for skin delivery. Moreover, a strong positive correlation between the amount of unfrozen bound water in meglumine-based systems and the bioadhesion properties was observed. This work shows that a better understanding of the physicochemical properties of a drug delivery system is extremely important for the correlation with the desired biological response and, thus, improve the product performance for biomedical applications.
Water addition to ‐unsaturated nitriles would give facile access to the ‐hydroxy‐nitriles which in turn can be hydrogenated to the ‐amino alcohols. We have previously shown that alcohols readily add in 1,4‐fashion to these substrates using Milstein's Ru(PNN) pincer complex as catalyst. However, attempted water addition to ‐unsaturated nitriles gave the 3‐hydroxynitriles in mediocre yields. On the other hand, addition of benzyl alcohol proceeded in excellent yields for a variety of β‐substituted unsaturated nitriles. Subsequent treatment of the benzyl alcohol addition products with TMSCl/FeCl3 resulted in formation of 3‐hydroxy‐alkylnitriles. The 3‐benzyloxy‐alkylnitriles obtained from oxa‐Michael addition also could be hydrogenated directly in the presence of acid to give the amino alcohols as their HCl salts in excellent yields. Hydrogenation under neutral conditions gave a mixture of the secondary and tertiary amines. Hydrogenation in the presence of base and Boc‐anhydride gave the orthogonally bis‐protected aminoalcohols, in which the benzyl ether can subsequently be cleaved to yield Boc‐protected amino alcohols. Thus, a variety of molecular scaffolds with a 1,3‐relationship between O‐ and N‐functional group is accessible starting from oxa‐Michael addition of benzyl alcohol to ‐unsaturated nitriles.
The aim of this research was to study the effect of stearic acid and TEA concentration on physical and chemical properties of cosmetic emulsion using coconut oil as raw material. The emulsion was made by emulsification of water phase (glycerin, aquadest and TEA) and oil phase (coconut oil, stearic acid, lanolin, cetyl alcohol). To determine the effect of stearic acid and TEA concentration on properties of emulsion, these components were added in various concentrations. The physical and chemical properties of emulsions were then measured such as pH, viscosity and droplet size. The result showed that the viscosity of emulsions was increased by increasing stearic acid concentration, on the other hand the droplet size decreased. The pH of emulsion was in the range of 7. 58-7. 96. If the TEA concentration was increased, the pH and viscosity were also increased, but it caused a decrease in droplets size. These mean that stearic acid and TEA concentration affected the physical and chemical properties of cosmetic emulsions.
Triethanolamine monolaurate ester was synthesized by lauric acid and triethanolamine (TEA) with a molar ratio around 1:1 and the esterification process was investigated and optimized. The esterification product of lauric acid with TEA was characterized by infrared spectra and nuclear magnetic resonance. The surface tension (γCMC) at the critical micelle concentration (CMC) was determined, and the antifogging properties of triethanolamine laurate ester on low-density polyethylene (LDPE) films were also measured. The results indicated that the yield of triethanolamine monolaurate ester was more than 69% under optimized esterification condition, the CMC value and γCMC of esterification product was 0.91 μg/mL and 22.1 mN/m in aqueous solution at 25 °C, respectively. The first-drop time and ten-drop time was 257 and 86 s, respectively, and the antifogging duration of triethanolamine laurate ester on the surface of LDPE film at 60 °C was more than 150 h.
Using D,L-lactic acid (LA) and multifunctional group compound triethanolamine (TEA) as starting materials, a novel biodegradable material poly(D,L-lactic acid-triethanolamine) [P(LA-TEA)] was directly synthesized by simpler and practical melt polycondensation. The appropriate synthetic condition was discussed in detail. When the molar feed ratio LA/TEA was 30/1, the optimal synthesis conditions were as follows: a prepolymerization time of 12 h; 0.5 weight percent (wt %) SnO catalyst; and melt copolycondensation for 8 h at 160°C, which gave a novel star-shaped poly(D,L-lactic acid) (PDLLA) modified by TEA with the maximum intrinsic viscosity [η] 0.93 dL g−1. The copolymer P(LA-TEA) as a different molar feed ratio was characterized by [η], Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Increasing the molar feed ratio of LA/TEA, Tg and Mw increased. However, all copolymers were amorphous, and their Tg (12.2°C–32.5°C) were lower than that of homopolymer PDLLA. The biggest Mw was 9400 Da, which made the biodegradable polymer be potentially used as drug delivery carrier, tissue engineering material, and green finishing agent in textile industry. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Protic ionic liquids (PILs) based on lipidic compounds have a range of industrial applications, revealing the potential of oil chemistry as a sustainable basis for the synthesis of ionic liquids. PILs of fatty acids with ethanolamines are here disclosed to form ionic liquid crystals, and their mixtures with the parent fatty acids and ethanolamines display a lyotropic behavior. Aiming at characterizing their rheologic and phase behavior, four ethanolamine carboxylates and the mixtures used for their synthesis through a Brønsted acid–base reaction are investigated. Their phase diagrams present a complex multiphase profile, exhibiting lyotropic mesophases as well as solid–liquid biphasic domains with a congruent melting behavior. These PILs present a high self-assembling ability and a non-Newtonian behavior with yield stress in the liquid crystal mesophase. The appearance of lamellar and hexagonal structures, with probably normal and inverted configurations in the mixtures, due to the formation of the PILs is responsible for the high viscoelasticity and notable nonideality that is mainly ruled by hydrophobic/hydrophilic interactions. Considering their renewable origin, the formation of liquid crystalline structures, in addition to the non-Newtonian behavior and ionic liquids properties, and the mixtures here evaluated possess a great potential, and numerous applications may be foreseen.
Using sodium caprylate as a model molecule, in the present work, we unraveled the gelation mechanism of sodium soaps in organic solvents from its correlation with the microstructure morphology. It is interesting to find that both the formation of organogels and radiation-like gel fibers are controlled by Na+ concentration in the system. As the gel-activator, the sodium ions not only accelerate the gelation process and enhance the gel networks, but also induce the morphology transformation from fibers to radiative nanoribbons. TEM and XRD characterization reveals that the Na+ enhanced effect should be ascribed to the structure transformation of sodium caprylate from layers to hexagonal packing, due to its reduced inter-separation after the addition of Na+. Based on these results, the gelation mechanism of sodium soaps has been also proposed.
Complex fluids with high concentrations of crystallizing fatty acids are important for consumer care products. The key features of these materials are their ability to support their weight under gravity and to yield or flow beyond a critical applied strain. To better understand the post-processing behavior of these systems, we have utilized a combination of Rheology, Differential Scanning Calorimetry, X-ray scattering, and Polarized Light Microscopy to study a model formulation consisting of two synthetic surfactants and a fatty acid (n-hexadecanoic acid) in water. Homogeneous samples with high storage modulus (G′) are realized due to the formation of a space filling solid fatty acid crystal network. A minimum of 5–7wt% of fatty acid is required to achieve the formation of a percolating crystal network. The storage modulus, yield stress and strain of these formulations show a non-monotonic increase with fatty acid content. This is attributed to the change in the fatty acid crystal habit from large to small aspect ratio plates. We hypothesize that the fatty acid crystal network consists of crystal aggregates linked by surfactant-fatty acid gels, rendering the desired paste-like characteristics to the formulation. The combination of methods utilized in this research provides a framework for understanding crystallizing systems.
Adding sodium salts to a dilute sodium laurate (SL) aqueous solution, slow phase transition was observed from the micelle solution to a gel phase. The phase-transition process has great resemblance to crystal salt-out. The observation by transmission electron microscopy (TEM) proved that the hydrogel is a network structure with interweaving fibers and ribbons, which can trap an aqueous solution. The images of high-resolution TEM (HR-TEM) indicated that each of the fibers and ribbons is composed of a bundle of parallel cylindrical nanofibers. Conductivity and in situ diffuse reflectance fourier-transform infrared (DR-FT-IR) spectroscopy measurements indicated that gel formation was induced due to a crystallization of rod micelles by Na+ ions bonding to the oxygengroups of salts of fatty carboxylates. Differential scanning calorimetry (DSC) showed that the increase of either the chain length of sodium soaps or the concentration of Na+ counter-ions promoted the growth of the nanofibers. We speculated that the phase transition from the micelle solution to the gel phase is a result of a crystallization of rod micelles induced by sodium ions.
A technically simple chemical method for the synthesis of mesoporous γ-alumina has been reported. Mesoporous γ-aluminas with
different pore structure and surface area were synthesized by using aluminium nitrate as a source of aluminum. Supramolecular
liquid crystalline phase of acid soap template synthesized via reaction of different carboxylic acids (stearic acid, oliec
acid and lactic acid) with excess of triethanolamine (TEA) acts as a structure directing agent and water was used as solvent.
Precursors were calcined at 550 °C in air for 2 h to obtain mesoporous alumina powders. Synthesized γ-alumina powders were
characterized by using thermogravimetric analysis, X-ray diffraction, high resolution transmission electron microscope and
N2 adsorption–desorption surface area and pore size analyzer. Pore size and ordering of pores were influenced by the chain length
of carboxylic acids. Surface area of synthesized alumina powders varied from 214 to 376 m2/g and average pore diameter from 3.3 to 6.5 nm depending upon the chain length of the carboxylic acid.
The Cosmetic Ingredient Review Expert Panel assessed the safety of triethanolamine (TEA) and 31 related TEA-containing ingredients as used in cosmetics. The TEA is reported to function as a surfactant or pH adjuster; the related TEA-containing ingredients included in this safety assessment are reported to function as surfactants and hair- or skin-conditioning agents. The exception is TEA-sorbate, which is reported to function as a preservative. The Panel reviewed the available animal and clinical data. Although data were not available for all the ingredients, the panel relied on the information available for TEA in conjunction with previous safety assessments of components of TEA-containing ingredients. These data could be extrapolated to support the safety of all included ingredients. The panel concluded that TEA and related TEA-containing ingredients named in this report are safe as used when formulated to be nonirritating. These ingredients should not be used in cosmetic products in which N-nitroso compounds can be formed.
More than 5 million tonnes of metal salts of fatty acids are manufactured and used worldwide every year, to create a range of soft condensed-matter products such as bar soaps, stick deodorants, personal care creams, toothpastes, and lubricant greases. These molecules, popularly known as soaps, are capable of forming a plethora of states and self-assembled aggregates such as micelles, liquid crystals, solid crystals, and gels, whose characteristic sizes or domain sizes can span from nanometers to centimeters. The type and mix of the phases formed, their morphologies, and their states of dispersion or the nature of their further supra-assemblies dictate the underlying micromechanical structures of products, which, in turn, are responsible for their optical, structural, and rheological properties. Developing processing guidelines to manipulate characteristic micromechanical structures is therefore key to obtaining the desired look, touch, feel, and function of these products. The article discusses a few illustrative examples of these structure−property relationships demonstrated by multiscale soap assemblies. Observations of some novel tertiary structures formed by crystallizing soap fibers at the air−water interface, serendipitously discovered by us in the recent past, are also discussed, to illustrate the richness and mysteries of the well-studied and so-called mature subject of soaps.
It is known that 12-hydroxystearic acid coupled via ion-pairing with a counterion, such as ethanolamine, self-assembles into supramolecular multilayer tubes that exhibit a peculiar temperature-tunable diameter variation. At a given temperature threshold (T(Ø↑)), there is a large increase of the tube diameter by almost a factor of 10. We investigate here the nature of the counterion on the self-assembly of such tubes and the variation of their diameter with the temperature. Eight different counterions are used to produce tubes via ion-pairing with 12-hydroxystearic acid. We systematically measure structural parameters at different scales coupling phase contrast microscopy and small-angle neutron scattering (SANS), in combination with thermodynamic studies using differential scanning calorimetry (DSC). The temperature T(Ø↑) is found to depend sensitively on the nature of the counterion. One could not identify any DSC peak associated with the diameter variation. However, a detailed line-shape analysis of the SANS spectra reveals that a significant softening of the elastic properties of the multilayer tube walls occurs at T(Ø↑), for all counterions investigated. Depending on both the temperature and the nature of the counterion, the interlayer spacing in the multilayered structure (respectively, the bilayer thickness) varies in a range from 240 to 440 Å (respectively, from 22 to 42 Å), but those variations appear not to be related to T(Ø↑). Altogether, our results show that the variation of the diameter is correlated to the nature of the counterion and to the elastic properties of the bilayer stack.
The behaviour of stearic acid neutralised by triethanolamine to form soap and its acid-soap has been examined by infrared spectroscopy. It was found that not only could the neutralisation behaviour be characterised, but the thermotropic behaviour could also be followed. The neutralisation confirmed the formation of a fixed stoichiometeric ratio, 2 : 1, acid-soap. When following the thermotropic behaviour the break up of the acid-soap could be followed along with various disordering and melting transitions of the alkyl chain tail. This allowed all the thermal transitions that have been observed to be characterised in terms of the type of molecular rearrangement that was occurring and also the transition temperature at which they occurred. This allowed the binary phase diagram to be plotted and understood for this system. This is the first time IR has been used to measure a whole phase diagram of this type. The nature of the acid-soap complex itself was also characterised, with very short hydrogen bonds being present as well as a free, non-hydrogen bonded, hydroxyl group.
Stearic acid or eicosanoic acid mixed with di- or oligomeric amines in specific molar ratios form stable gels in water. The formation of such hydrogels depends on the hydrophobicity of the fatty acid, and also on the type of amine used. The gelation properties of these two-component systems were investigated using electron microscopy, FTIR spectroscopy, 1H NMR spectroscopy, differential scanning calorimetry (DSC), and both single-crystal and cast-film X-ray diffraction. Results of FTIR spectral analysis suggest salt formation during gelation. 1H NMR analysis of the gels indicates that the fatty acid chains are immobilized in the gel state and when the gel melts, these chains regain their mobility. Analysis of DSC data indicates that increase in the spacer length in the di-/oligomeric amine lowers the gel-melting temperature. Two of these gelator salts developed into crystals and structural details of such systems could be secured by single-crystal X-ray diffraction analysis. The structural information of the salts thus obtained was compared with the XRD data of the self-supporting films of those gels. Such analyses provided pertinent structural insight into the supramolecular interactions that prevail within these gelator assemblies. Analysis of the crystal structure confirmed that multilayered lamellar aggregates exist in the gel and it also showed that the three-dimensional ordering observed in the crystalline phase is retained in only one direction in the gel state. Finally, the hydrogel was used as a medium for the synthesis of silver nanoparticles. The nanoparticles were found to position themselves on the fibers and produced a long, ordered assembly of gel-nanoparticle composite.
The phase diagrams of six different alkanolammonium carboxylate-water systems have been determined. Their phase behavior differs from that of ordinary soaps, since there are large differences between the systems for varying alkyl chain lengths of the carboxylate. In addition, the chemical structure of the alkanolammonium counterion also effects the phase equilibria. For short alkyl chain carboxylates the liquid crystalline phases disappear (e.g., for the triethanolammonium octanoate) or decrease in extension (e.g., for monoethanolammonium octanoate), although the surfactant readily aggregates in solution. In contrast, long alkyl chain carboxylates behave like swelling amphiphiles with a low aqueous solubility and the immediate formation of a lamellar phase (e.g., for tri- and monoethanolammonium oleate). It is shown that the distribution between acid and soap causes these effects. The lower surface charge of the surfactant aggregates compared to that of ordinary soap micelles is also reflected in a lowering of the critical micellization concentration.
Previous studies of the occurrence of acid soaps in systems containing a longchain sodium soap and the corresponding fatty acid, and the study of phase equilibria in the system sodium octanoate — octanoic acid — water, performed by our group at the beginning of the 1960s, show that the isotropic liquidL
2-phase of the last mentioned system in its whole region of existence is situated in that part in which acid soaps occur. This provides an explanation for the fact that theL
2-phase itself contains acid sodium octanoates in all regions. TheL
2-phase has its origin in the water-free melt of fatty acid and neutral soap in which these components react with each other under the formation of an acid soap. When water is added to the system, this water-free acid soap is transformed into different hydrated acid soaps. In a large region of concentration, there is an extremely close relation between theL
2-phase and the liquid-crystalline lamellarD-phase, which itself consists of hydrated acid soaps. At its outermost water-rich tip, theL
2-phase is in equilibrium with theL
1-phase of the system, just above the+LAC, that is, with the most dilute aqueous soap solution in which acid soap still may be formed in aqueous environment. Formation of acid soap is a fundamental requirement for the existence of this isotropic liquidL
2-phase.
IR spectra in the 7.5–25.0 m region are shown to be unique for polymorphic modifications of long chain saturated fatty acids
of even carbon number and also for the individual fatty acids. IR spectra are presented for the A-, B-, C- and E-forms of
stearic acid and for the C-form of myristic, palmitic, arachidic and behenic acid and the differences discussed. X-ray determined
crystal long spacings for the A-, B-, C- and E-forms of a series of homologous even carbon-numbered acids are presented and
compared with literature values. The formation of the different polymorphic forms are found to be temperature-concentration
related and affected little by polarity of the solvent. Wideline nuclear magnetic resonance second moment values are given
for the polymorphic forms of stearic acid.
A high-sensitivity apparatus for thermoanalytical microscopy under reflected light has been designed and has been applied to studies of (1) the mechanism of the polymorphic transition of stearic acid, (2) the fine structure of the smectic—cholesteric transition of cholesteryl nonanoate and (3) the process of the multiplication of yeast bacteria.
The crystallization of A, B and C polymorphs of stearic acid was examined in polar (methanol) and nonpolar (decane and benzene) solutions. First, the stability of the three modifications was determined by comparing the relative degree of solubility of each polymorph; B and C are the most stable forms below and above about 30°C respectively, whereas the A form is unstable at any temperature. Thereafter, the occurrence of the three forms was investigated by controlling the effects of temperature, supersaturation and solvent independently. The general trend is that: in nonpolar solvents, the A and C forms prevail at higher supersaturation, while the B form preferably occurs at lower supersaturation; in polar solvents, the occurrence domain of B is more extended towards the higher supersaturation range. In all cases, particularly in nonpolar solvents, the relative importance increases for A and C but decreases for B with increasing temperature. This trend was semi-quantitatively interpreted on the basis of a homogeneous nucleation rate function. Further, it was shown that a variety of previous studies, which have been so far rather contradictory to each other, could consistently be explained by the present study taking the thermodynamic and kinetic parameters in the crystallization process into account.
Submicrometer-sized large unilamellar vesicles (LUVs) prepared from a mixture of oleic acid and sodium oleate transformed into cell-sized giant vesicles (GVs) with dimensions of several micrometers on (or close to) glass surfaces and in the presence of adsorbed hydrocarbons such as squalane. GV growth was observed generally for fatty acids but not for double-chain phospholipids.
The cooperative mechanism of oleic acid/oleate vesicle formation is investigated under a variety of conditions. When a stock solution of sodium oleate is injected in a buffered aqueous solution of pH 8.8, the time progress of the vesicles formation follows a sigmoidal pattern, which is indicative of an autocatalytic process. Autocatalysis is demonstrated by running experiments in the presence of preadded vesicles, which shortens the lag phase and accelerates the process of vesicle formation as measured by turbidity and electron microscopy. The size distribution of the vesicle diameters obtained by injection of the surfactant stock solution in buffer solution covers a wide range, typically between 50 nm and 1.5 μm. However, in the presence of extruded vesicles having respectively 50 and 100 nm diameter, a quite different situation is observed: the size distribution is then much narrower and strongly biased toward the diameter of the preadded vesicles (i.e., 50 or 100 nm). It is as if the vesicles which are originally present would exercise a kind of template (or matrix) effect upon the new vesicles. This “matrix” effect is studied under a variety of concentration conditions of the preadded vesicles and the added surfactant stock solution. It is also investigated with a heterogeneous system, in which the water-insoluble and overlaid oleic anhydride is hydrolyzed in the presence and in the absence of preadded vesicles, and tendentiously the same matrix effect is observed. It is argued that this is most likely due to a prerequisite binding of the injected surfactant to the already existing vesicles, and it is this binding which determines the final size distribution.
A quantitative interpretation of abnormal hydrolysis in fatty acid soap solutions is presented, based on the possible precipitation of one or two out of three solid phases: fatty acids, acid soaps, and neutral soaps. For each of these possibilities theoretical pH is calculated as a function of the total amount of soap added. On the other hand, pH measurements yield a new and simple method for the evaluation of composition and solubility parameters of the precipitates formed. Experimental evidence is given for the potassium salts of C10, C12, C14, C16, and C18 fatty acids at 20°. In all cases the acid soap solid phase was found to have a 1:1 ratio between fatty acid and potassium carboxylate, independent of the ratio of these components in the solution. The logarithm of the solubility (product) of fatty acid, acid soap, and neutral soap, found from the measured pH values, decreased linearly with increasing chain length. Insertion of their numerical values into theoretically derived formulas leads to the conclusion that from low chain length potassium soap solutions only neutral soap crystals or micelles are formed (number of carbon atoms n < 9); at intermediate chain lengths (8 < n < 14) acid soap is first precipitated, whereas at high chain lengths (n > 13) fatty acid is first formed, followed by acid soap and neutral soap at higher concentrations.
Reaction of the caroviologen models CV2+ 1, 2, and 3 with aquated electrons generated by pulse radiolysis yields the corresponding cation radicals CV.+. The transient absorption of the latter is consistent with a large delocalization of the charge. The decay kinetics fit a disproportionation reaction scheme yielding the doubly reduced CV0 species. The rate of disproportionation increases with the number of conjugated double bonds; this may result from the combined effect of charge delocalization and increased flexibility. Evidence for cis-trans isomerization of CV.+ is presented.
The mechanism of the occurrence and the crystal growth of the B form of stearic acid (n-C18 acid) has been investigated by means of IR spectroscopy. It has been clarified that on the crystallization process the B form occurs not directly from solutions but through a heterogeneous nucleation on the (001) face of the single crystals of E generated at the first stage and a subsequent solid-state phase transition from E to B. The E --> B transition achieves through the reorientation of dimerized carboxyl groups accompanied with the conformational change from trans to gauche at the C2-C3 bond, while most of acyl chain maintains its original orientation. Since the direction of the crystallographic axes as well as the crystal habit is kept unaltered during the transition, the E --> B phase transition is regarded as a topotactic transition.
Crystallization processes of B and E forms of stearic acid were investigated by means of infrared spectral measurement and microscopic observation. Polymorphic and polytypic transformations took place during the crystal growth in a solution. The single-layered polytype of the E form was generated at first, and the overgrowth of the double-layered polytype of E took place on the (001) face of the single-layered one. The polymorphic transformation from E to B occurred for specific single crystals. The single crystal of B grew as a single-layered polytype in the initial stage, consuming crystals of the unchanged E crystals through solution-mediated phase transformation. In the chemical etching experiment, the crystals that had been transformed to B quickly exhibited many etch pits due to screw dislocations on the (001) face, whereas there were very few pits on the unchanged crystals. This fact strongly suggests that the E --> B transition would proceed in one single crystal along the spiral structure due to screw dislocations.
Stearic acid has been crystallized from various organic solvents at different crystallization conditions. — The crystal structure modifications, A, B or C of the fatty acid are correlated to the solvent properties and depend on the interplay between the effect of the crystallization conditions and the solvent/solute interactions.
Stearinsäure wurde aus mehreren Lösungsmitteln unter verschiedenen Bedingungen auskristallisiert. — Die Kristallstrukturmodifikationen A, B oder C der Fettsäuren hängen von den Lösungseigenschaften ab und werden beeinflußt vom Spiel der Kräfte zwischen den Kristallisationsbedingungen und der Wechselwirkung zwischen Lösungsmittel und gelöster Substanz.
Various types of molecular assembly of long-chain compounds in solid states were investigated by means of infrared absorption, Raman and Brillouin spectroscopic methods. As for the polymorphism in even-numbered n-fatty acids, three monoclinic modifications, B, C, and E, all consisting of the orthorhombic polyethylene sublattice, give rise to their characteristic infrared and Raman spectra. A dynamical equilibrium between cis and trans conformations of the hydrogen-bonded carboxyl groups in modification C, which is related to the high-temperature stable character of this phase, is reflected to a dramatic change with temperature in the low-frequency Raman spectra. A new type of reversible solid state phase transition was found between two A-type (triclinic) modifications of myristic, palmitic, and stearic acids. The γα phase transition of oleic acid was found to be caused by a conformational disordering of polymethylene chains at the lamellar interfacial region.
IR and NMR studies of the solutionsL
2 have yielded following information on the structure of the solutions in this region.
Sodium caprylate dissolves in water-free caprylic acid to form an acid soap with the composition 1 NaC8 ·2 HC8 dissolved in the acid. The soap and acid are bound by strong hydrogen bonds. When water is added to this solution these bonds are dissolved and the water molecules bound; only at a water content of 40–50 per cent is this process completed. The destruction of the strong hydrogen bonds between soap and acid enable more fatty acid to be bound to the soap in the concentration range where there is enough acid — that is when the caprylic acid content is higher than 70 per cent; in this range there forms an acid soap with the composition 1 NaC8·3 HC8·x H2O.
Spectroscopic measurements in the long, narrow salient of the region L2 show that in the solution when the water content exceeds 40–50 per cent “free” water occurs. At the same concentration there begins a greatly increased interaction between the methylene groups of the hydrocarbon chains. The results are consistent with the view that the solution changes from being a hydrocarbon-continuous one to being a water-continuous one.
The isotropic liquid pase,L
2, in the system sodium octanoate/octanoic acid/ water (at 20 C) exhibits low-angle X-ray scattering. The strength of the phenomenon and the position of the peak in the scattering curve vary with composition. This phenomenon is presented and described.
A study of the interaction between a model skin surface lipid (SSL) and an oil base skin softener (G2) was made by comparing
the phase behavior of these substances in combination with the water/triethanolamine: oleic acid (1:1 wt ratio) system. A
principle feature of the water/G2/triethanolamine:oleic acid (TEA:OL) system was the formation of a lamellar liquid crystal
region that incorporated an average of 40% G2 over the 10–45% water range. The phase behavior of the water/SSL/TEA:OL system
demonstrated only over a 4–9% water range. At greater than 5% SSL, there is the complete absence of single phase regions above
10’% water.
From comparison of the phase regions and the small angle X-ray diffraction results, it is found that for G2/SSL mixtures the
phase behavior of the lamellar liquid crystal is dominated by the SSL and the interlayer spacing of the lamellar liquid crystal
is dominated by G2.
Structured and semisolid emulsions intended for application to the skin and mucus membranes (i.e. lotions and creams) are generally complex mixtures of excipients whose stability and bioavailability vary greatly. A knowledge of the physicochemical properties of such formulations is essential to optimize manufacturing conditions, provide cosmetic elegance and to optimize the delivery of the drug or cosmetic agent to the skin. This paper discusses the manner in which surfactants and fatty amphiphiles combined to form mixed emulsifiers and emulsifying waxes have the ability to (a) promote emulsification at the time of manufacture by the stabilization of oil droplets, (b) control stability during a shelf-life that can vary from days for extemporaneously prepared emulsions to months or years for commercial preparations and (c) control the rheological properties of the system by their interaction with water and other excipients in the external phase. The use of simple model systems to investigate these complex formulations is demonstrated.
The infrared spectra of four different crystal forms of octadecanoic acid were investigated with the aid of a Perkin-Elmer Model 112 double-pass spectrometer equipped with polarizer and reflecting microscope. For the triclinic A-form spectra of a single crystal were observed with the electric field in the linearly polarized incident radiation parallel and perpendicular to the skeletal planes of the methylene chains. For the monoclinic B- and C-forms spectra were obtained of single crystals, and of suitably cut slices of single crystals, with the electric field parallel to the a-axis, the b-axis, the c-axis, and perpendicular to the c-axis. A new, evidently monoclinic, crystal form was discovered, and spectra of a single crystal of this form were obtained with the electric vector parallel to the a- and b-axes. Deuterated octadecanoic acid, CH3(CH2)16COOD, was prepared, and spectra were obtained of single crystals having the C-form and the new form. The spectral data were used to verify, extend or revise previous interpretations of the infrared bands of octadecanoic acid.
The state behavior of stearic acid-sodium stearate-water, which provides a model of a fatty acid structuring mechanism, was studied by differential scanning calorimetry (DSC), optical microscopy, and X-ray scattering. DSC mapped the state diagram of aged and quenched samples as a function of temperature. Optical microscopy identified a liquid crystal transition. Simultaneous small- and wide-angle X-ray scattering identified the structures present within different regions of the state diagram. Two acid/soaps differing in melting temperature, unit cell, lamellar spacing, and acid to soap chain ratio existed at room temperature. In half-neutralized samples, a lamellar hydrated gel phase with an hexagonal unit cell persisted to room temperature on quenching. Nonequilibrium behavior persisted to different degrees depending on the extent of neutralization of the system.
In studies of the minimum physiochemical requirements for lipid membrane formation, we have made liposomes from dilute, aqueous dispersions of C(8)-C(18) single-chain amphiphiles. In general, membrane formation from ionic soaps and detergents requires the presence of uncharged amphiphiles. Vesicles were characterized by phase-contrast microscopy, by trapping of ionic dyes, as well as by negativestain and freez-frature electron microscopy. They were typically heterogeneous in size, but the average diameter could be experimentally varied in some cases over the range of 1 to 100 micrometer. Uni-, oligo-, and multilamellar vesicles were observed. Membrane permeability to various solutes was determined in part by a new technique which utilized phase-contract microscopy; when impermeable vesciles exclude added solutes such as sucrose, refractive index differences are created between vesicle contents and surrounding medium, so that the vesicles appear bright in the phase microscope. Permeant solutes do not produce this effect. Spectrophotometric permeability determinations confirmed the results of this technique and provided quantitative measures of permeability. Monoalkyl liposomes have potential uses as models of biomembranes and in drug delivery. They are also relevant to the prebiotic origin of biomembranes.
The physical properties in water of a series of 1:1 acid-soap compounds formed from fatty acids and potassium soaps with saturated (10-18 carbons) and omega-9 monounsaturated (18 carbons) hydrocarbon chains have been studied by using differential scanning calorimetry (DSC), X-ray diffraction, and direct and polarized light microscopy. DSC showed three phase transitions corresponding to the melting of crystalline water, the melting of crystalline lipid hydrocarbon chains, and the decomposition of the 1:1 acid-soap compound into its parent fatty acid and soap. Low- and wide-angle X-ray diffraction patterns revealed spacings that corresponded (with increasing hydration) to acid-soap crystals, hexagonal type II liquid crystals, and lamellar liquid crystals. The lamellar phase swelled from bilayer repeat distances of 68 (at 45% H2O) to 303 A (at 90% H2O). Direct and polarized light micrographs demonstrated the formation of myelin figures as well as birefringent optical textures corresponding to hexagonal and lamellar mesophases. Assuming that 1:1 potassium hydrogen dioleate and water were two components, we constructed a temperature-composition phase diagram. Interpretation of the data using the Gibbs phase rule showed that, at greater than 30% water, hydrocarbon chain melting was accompanied by decomposition of the 1:1 acid-soap compound and the system changed from a two-component to a three-component system. Comparison of hydrated 1:1 fatty acid/soap systems with hydrated soap systems suggests that the reduced degree of charge repulsion between polar groups causes half-ionized fatty acids in excess water to form bilayers rather than micelles.(ABSTRACT TRUNCATED AT 250 WORDS)
Crystals of partially neutralized stearic acid with triethanolamine (TEA) were prepared by mixing these two materials above 80 degrees C and then cooling. The crystalline composition and the structure and melting behavior of the resultant products were characterized with small-angle and wide-angle X-ray diffraction, thermal analysis, microscopy, and infrared spectroscopy. It was discovered that an acid-soap complex of 2:1 fixed stoichiometric ratio exists between stearic acid and TEA stearate. A binary phase diagram of stearic acid and TEA soap is built based on the experimental results; this is the first published record of a binary phase diagram for amine-based soap. Its behavior is significantly different from that of binary systems of fatty acid and alkali soap.
- F Kaneko
- T Simofuki
- H Miyamoto
- M Suzki
(24) Kaneko, F.; Simofuki, T.; Miyamoto, H.; Suzki, M. J. Phys. Chem.
1992, 96, 10554-10559.
- K Morigaki
- P Walde
- W Langmuir Hargreaves
- D Deamer
(31) Morigaki, K.; Walde, P. Langmuir 2002, 18, 10509-10511.
(32) Hargreaves, W.; Deamer, D. Biochemistry 1978, 17, 3759-3768.
- Chem Kunihisa
- K Thermochim
- E Acta Stenhagen
- R Sydon
- F Kaneko
- H Sakashite
- M Kobayashi
- D P Cistola
- D Atkinson
- J A Hamilton
- D Small
Chem. 1992, 96, 10554-10559.
(16) Kunihisa, K. Thermochim. Acta 1979, 31, 1-11.
(17) Stenhagen, E.; Sydon, R. Ark. Kemi Band 1952, 6, 309-316.
(18) Kaneko, F.; Sakashite, H.; Kobayashi, M. J. Phys. Chem. 1994,
98, 3801-3808.
(19) Cistola, D. P.; Atkinson, D.; Hamilton, J. A.; Small, D. Biochemistry
1986, 25, 2804-2812.
(20) Ekwall, P. Colloid Polym. Sci. 1988, 266, 279-282.
(21) Ekwall, P.; Fontell, K. Colloid Polym. Sci. 1988, 266, 184-191.
(22) Kobayashi, M. In Crystallisation and polymorphism of fats and
fatty acids; Garti, N., Sato, K., Eds.; Marcel Dekker: New York, 1988; p
139.
(23) Kobayashi, M.; Kobayashi, T.; Cho, Y.; Kaneko, F. Makromol.
Chem., Macromol. Symp. 1986, 5, 1-20.
Manuscript in preparation
- P D A Pudney
- K J Mutch
- S Zhu
- R F Holland
- J R Nielsen
(25) Pudney, P. D. A.; Mutch, K. J.; Zhu, S. Manuscript in preparation.
(26) Holland, R. F.; Nielsen, J. R. J Mol. Spectrosc. 1962, 9, 436-460.
- K Eisemann
(28) Eisemann, K. J. Chem. Educ. 1949, 26, 607-609.
- J J Mcbain
- Soc
(30) McBain, J. J. Soc. Chem. Ind. 1918, 37, 249-252.
- D Ferdinando
- K Mutch
Ferdinando, D.; Mutch, K. J. J. Phys. Chem. B 2005, 109, 11753-11761.
- J Lucassen
(29) Lucassen, J. J. Phys. Chem. 1966, 70, 1824-1830.