Phase behavior of sucrose monoalkanoate in a water-long-chain alcohol system

Phase diagram of a water/sucrose monododecanoate (SE)/hexanol system was determined at 30°C. Aqueous micellar, reverse micellar, normal hexagonal liquid crystalline, and lamellar liquid crystalline phases appear in the phase diagram. The change in interlayer spacing and interfacial section area of surfactant in the liquid crystalline phases was investigated by small-angle x-ray scattering. Upon addition of water, the section area and the radius of cylindrical aggregates are almost constant in a hexagonal liquid crystal, whereas the distance between each cylinder is separated on the water-SE axis. The interlayer spacing slightly decreases or is almost unchanged on the surfactant-hexanol axis, because alcohol molecules penetrate into the palisade of bilayers. Although the average section area decreases with increasing alcohol content, each section area of SE and alcohol molecules are kept constant. Since the interfacial section area of alcohol is less than the section area of hydrocarbon chain, the phase transition from lamellar liquid crystal to reverse micelle occurs in an alcohol-rich region.     

Phase equilibria and structures in ternary systems of a cationic surfactant (C16 TABr or (C16 TA)2SO4), alcohol,and water

The dependence of alcohol chain length on the isothermal phase behavior of the ternary systems hexadecylrrimethylammonium bromide/alcohol/water has been investigated. A liquid crystalline phase (the normal hexagonal one) occurs in the phase diagrams along the surfactant/water axis and this phase extends in the interior of the diagrams.When the alcohol is methanol, ethanol or butanol, there is in the ternary phase diagram a continuous solution region from the water to the alcoholic corner, and in the butanol case, in addition, a small region of lamellar liquid crystalline phase in the interior of the diagram. When the alcohol chain length is increased, the continuous solution region is divided into two subregions, an aqueousL ₁ and an alcoholicL ₂. The lamellar phase occupies the center of the phase diagrams and has the capability to incorporate large amounts of water under one-dimensional swelling. On the alcoholic side of the lamellar phase occur a reversed hexagonal liquid crystalline phase and a cubic liquid crystalline phase in the octanolic system; in the decanolic system the cubic phase is missing, but instead another liquid crystalline phase, presumably with rod-structure, occurs in addition to the reversed hexagonal phase.In a decanolic system where the monovalent bromide ion is replaced by the divalent sulphate ion there are the same solution regionsL ₁ andL ₂, and phase regions with liquid crystalline normal hexagonal and lamellar structures. The lamellar phase has lost much of its capability of incorporating water. That is in analogy with the conditions in anionic systems where the counterion charge has been increased. There is no reversed hexagonal phase, but on the alcoholic side of the lamellar phase, there is the same foreign liquid crystalline phase with a presumed rod-structure as in the monovalent system.     

Surfactant association structures in the system water,sorbitol, sodium dodecyl sulfate,and hexanol

The phase regions in the system hexanol, sodium dodecyl sulfate, and concentrated aqueous solutions of sorbitol were similar to the corresponding system with glycerol.In addition to the expected phase regions of a water/sugar micellar solution, a lamellar liquid crystalline phase, and the alcohol solution with solubilized sugar and water, a small region was found with an extremely stable emulsion, which could be separated by ultracentrifugation at 108,000 g. This emulsion consisted of micron sized droplets separated by layers of a lamellar liquid crystal.     

Phase equilibria and phase structure in the ternary systems sodium or potassium octanoate-octanoic acid-water

Two isotropic solution regions and several liquid crystalline regions occur in the ternary system sodium octanoate-octanoic acid-water at 20°C The solution regions are an aqueous solution and a solution of sodium octanoate and water in liquid octanoic acid. A region displaying one-dimensional lamellar structure is located in the center of the phase diagram. A region along the soap-water axis has a two-dimensional normal hexagonal structure. Another region at high octanoic acid content has a reversed hexagonal structure. Along the soap-fatty acid axis the acid-soap 2NaC₈:1HC₈ in crystalline state is found.X-ray and density findings for the various phases are presented, and structural parameters for the different liquid crystalline phases are estimated.The phase behavior of the potassium soap system is similar to that of the sodium system.The isothermal ternary phase diagram of a soap, the corresponding fatty acid and water provides information about the ionization state of the system, from the unionized fatty acid to the fully ionized soap.     

Dissipative particle dynamics simulation of phase behavior of aerosol OT/water system

The phase behaviors of the binary mixture of an anionic surfactant aerosol OT (AOT) and water are investigated on a mesoscopic level using dissipative particle dynamics (DPD) computer simulations. With a simple surfactant model, various aggregation structures of AOT in water including the lamellar, viscous isotropic, and reverse hexagonal phases are obtained, which agree well with the experimental phase diagram. Special attention is given on the unusual lamellar regions. Water diffusivity shows much useful information to understand how the phase behaviors varied with concentration and temperature. It is proposed that the anomalous lamellar phenomena at intermediate AOT concentration (about 40%) are due to the formation of a defective structure, pseudoreversed hexagonal phase, which evidently decreases the water diffusivity. After increasing temperature above 328 K, the pseudoreversed hexagonal structure will be partly transformed to a normal lamellar phase structure and the system lamellar ordering is therefore enhanced.     

Studies on the phase properties of lyotropic liquid crystals of Brij35/sodium oleate/oleic acid/water system:By means of polarizing microscope,SAXS,~2H-NMR and rheological methods

The pseudo-quaternary phase diagram of Brij35/sodium oleate/oleic acid/water systems has been investigated, and the liquid crystal area has been identified, which covers about two thirds of the whole phase diagram. The liquid crystal structure and behavior have been also studied by using polarizing texture, small angle X-ray scattering, 2H-NMR and rheometer etc. The result shows that when the composition of the system changes along the line of AA′ in this large liquid crystal region, the structural change is cubic→cubic/lamellar→lamellar→lamellar/hexagonal→hexagonal. Meanwhile, we made the first attempt of systematic study of the rheological properties of the above system. The lattice constants of cubic and hexagonal liquid crystals are 10.53 and 5.68 nm, respectively.     

Phase behavior of polyglycerol didodecanoates in water

A phase diagram of a water-polyglyceryl didodecanoate ((C11)2Gn) system was constructed as a function of polyglycerol chain length (n) at 25 degrees C. The average number of dodecanoic acid residues attached to polyglycerol is in the range of 1.6-2.3, and unlike commercial long-chain polyglycerol surfactants, unreacted polyglycerols were removed in the surfactants used. With an increase in the polyglycerol chain, the surfactant changes from lipophilic to hydrophilic, and the type of self-organized structure also changes from lamellar liquid crystals to the aqueous micellar solution phase via hexagonal liquid crystals. However, a discontinuous micellar cubic phase does not appear in the phase diagram, while it is formed in a long poly(oxyethylene)-chain nonionic surfactant system. In a dilute region, a cloud point is observed at a moderate polyglycerol chain length, n approximate to 7. The cloud temperature is dramatically increased with a slight increase in hydrophilic chain because the dehydration of the hydrophilic chain length at high temperature is low compared with that of the poly(oxyethylene) chain. In other words, the phase behavior of (C11)2Gn is not very temperature sensitive. Three-phase microemulsion is formed in a water/(C11)2.3G7.3/m-xylene system. The three-phase temperature or HLB temperature is highly dependent on the polyglycerol chain length.     

Phase polymorphism by mixing of poly(oxyethylene)-poly(dimethylsiloxane) copolymer and nonionic surfactant in water

The phase behavior of the water/poly(oxyethylene)-poly(dimethylsiloxane) copolymer (Si25C3EO51.6)/pentaoxyethylene dodecyl ether (C12EO5) ternary system has been studied. Both the silicone copolymer and the surfactant have equal volumes of hydrophilic and lipophilic parts; i.e., these are balanced amphiphiles. Although only a lamellar phase is observed in water-Si25C3EO51.6 and water-C12EO5 binary systems, a variety of liquid crystalline phases, including normal micellar cubic (I1), hexagonal (H1), bicontinuous cubic (V1), lamellar (L(alpha)), reverse bicontinuous cubic (V2), and reverse hexagonal (H2), are observed in the copolymer-rich region of the ternary phase diagram. The small C12EO5 molecules dissolve at the hydrophobic interface in the thick bilayer of the Si25C3EO51.6 L(alpha) phase occupying a large area of the total interface of the aggregates and modulate the curvature of the aggregates. Hence a variety of self-assembled structures are observed. In contrast, Si25C3EO51.6 is not dissolved in the thin bilayer of the C12EO5 lamellar phase (L'(alpha)). Hence, the C12EO5 L'(alpha) phase coexists with copolymer-rich L(alpha) and H2 phases. Consequently, small surfactant molecules are dissolved in a large silicone copolymer aggregate to induce a change in layer curvature, but a large copolymer molecule is hard to incorporate with surfactant aggregates.     

Studies of Phase Behavior on R12TAB/Benzyl Alcohol/Water Ternary System

Phase behavior of ternary systems containing 3‐dodecyloxy‐2‐hydroxypropyl trimethyl ammonium bromide (R₁₂TAB), benzyl alcohol and water have been studied at 25±0.1°C. Ternary phase diagram of the systems shows a clear, isotropic, and low‐viscous region, a L phase, two liquid crystalline phases (lamella and hexagonal liquid crystal), and a coexisted phase of the liquid crystalline and micelles. ²H nuclear magnetic resonance (²H NMR) technology and polarizing‐light microscope were employed to confirm the symmetry structure of the liquid crystals and the boundaries for the different phases. In L phase, three types of different micelle regions (reverse micelles, normal micelles, and bicontinuous structures zones) were confirmed by means of the electric conductivity and the proton nuclear magnetic resonance spectroscopy (¹H NMR) measurements. The microcosmic structures of the micelle were investigated, and the solubilizing position of benzyl alcohol were located according to the chemical shift of protons.     

Partial Phase Diagrams in the System Water/Formamide/Sodium Dodecyl Sulfate/Decanol

The phase regions were determined in the systems of sodium dodecyl sulfate, decanol and a polar solvent. The latter was a) water, b) water and formamide (1/1 weight ratio) and c) formamide

The water system showed an aqueous micellar solution, a decanol solution with inverse micelles as well as a lamellar and a hexagonal liquid crystal. The formamide system gave a formamide solution, a lamellar liquid crystal and a decanol solution while the system with water plus formamide in a 1/1 ratio still retained the hexagonal liquid crystal.     

Cubic, sponge, and lamellar phases in the glyceryl monooleyl ether-propylene glycol-water system

The phase behavior of 1-glyceryl monooleyl ether (GME) in mixtures of propylene glycol (PG) and water was investigated by visual inspection, polarization microscopy, small-angle X-ray diffraction, and conductance measurements. A phase diagram, based on over 200 samples of the ternary system GME-PG-water, was constructed at 20 degrees C. Without PG, GME forms a reverse micellar phase with up to 10 wt % water and a reverse hexagonal liquid-crystalline phase between 10 and 25 wt % water, a phase that can coexist with excess water. If PG is added in amounts exceeding about 10 wt %, then cubic and lamellar liquid-crystalline phases start to form. A cubic phase, belonging to space group Pn3m, can coexist with excess PG-water mixtures. If even more PG is added, then the cubic phase is transformed into a sponge phase. A lamellar phase forms at water contents between 10 and 15 wt % and with widely differing PG/GME weight ratios. We postulate that the phase behavior is caused by the fact that PG makes the interfacial region between self-assembled GME and PG-water less negatively curved, which in turn allows for the formation of the new phases. The phase behavior obtained for the GME system shows a striking similarity with the phase behavior of the corresponding system in which the GME has been replaced by the ester, 1-glycerol monooleate (GMO), differing only in one extra carbonyl oxygen. The major difference is the lower amount of water present in the GME phases, an effect that is mainly due to the more hydrophobic character of GME compared to that of GMO.     

Triton X-100/C10H21OH/H2O体系微乳液与溶致液晶

关于离子型表面活性剂生成的微乳液与溶致液晶已有不少研究，非离子型表面活性剂生成的微乳液与港致液晶的应用正在引起人们的重视，但由于药物提纯的困难，对其物理化学性质的研究还不多见．本文以非离子表面活性剂TritonX－100／C10H21OH／H2O体系为例，研究了非离子型表面活性剂微乳液和溶致液晶的生成及其结构特性．1实验部分试剂ThitonX－100（Aldrich公司，分析纯）正癸醇（分析纯）、水为一次蒸馏水微乳液区域和层状液晶区域的确定方法及小角x射线衍射测定方法同文献，实验温度20±0．1℃．2结果与讨论2·IThtonX－100、CIOH…     

Phase behavior of a DNA-based surfactant mixed with water and n-alcohols

The self-assembly behavior of a cationic surfactant (dodecyltrimethylammonium, DTA) with DNA as counterion in mixtures of water and n-alcohols (decanol, octanol, hexanol, butanol, and ethanol) was investigated. The phase diagrams were established and the different regions of the phase diagram characterized with respect to microstructure by (2)H NMR, small-angle X-ray scattering (SAXS), and other techniques. The DNA-DTA surfactant is soluble in all of the studied alcohols, showing increased solubility from decanol down to ethanol. All of the phase diagrams are analogous with respect to the occurrence of liquid crystalline (LC) regions, but the area of the LC region increases as one goes from decanol to ethanol. In all phase diagrams, hexagonal phases (of the reversed type) for the alcohol-rich side and lamellar phases for the other side were detected. For balanced proportions of the components, there is a coexistence of the lamellar and the hexagonal phase, here detected with a double quadrupole splitting in the (2)H NMR spectra. The correctness of the phase diagrams is confirmed by the fact that along the tie-lines the splitting magnitude remains nearly constant. All of the alcohols except for ethanol act as cosurfactants penetrating the DNA-DTA film. Adding salt to the ternary mixtures causes an increase in the unit cell dimension of the lamellar and the hexagonal phases. The phase diagram becomes more complicated when butanol is used for the alcohol phase. Here, there is the occurrence of a new isotropic phase with some properties analogous to those of the disordered sponge (L3) phase obtained for simple surfactant systems.     

The catanionic system dodecyltrimethylammonium hydroxide–n-dodecanephosphonic acid–water. Triangular phase diagram

 The triangular phase diagram of the system dodecyltri-methylammonium hydroxide (DTAOH)–dodecanephosphonic acid (H₂DP)–water was studied by several techniques. The DTAOH-rich zone could not be studied because DTAOH decomposed when it was dried. Pure H₂DP only forms lamellar mesophases with water. The inclusion of DTAOH in the system produces the appearance of cubic and hexagonal mesophases. The gradual increase in DTAOH proportion lead to the gradual reduction in the existence of the lamellar mesophase domain, and increase of the hexagonal liquid crystal domain. At high DTAOH content, the lamellar mesophase disappeared. This behavior was explained by the gradual destruction of the hydrogen-bonded structure in the polar headgroup layer of liquid crystal aggregates. H₂DP-rich anhydrous crystals were triclinic. Received: 8 September 1997 Accepted: 17 February 1998     

Effects of nonionic surfactant C12E5 on the cooperative dynamics of water

A dielectric relaxation study of binary mixtures of nonionic surfactant C12E5 + water has been made as a function of temperature in the isotropic micellar, lamellar, and hexagonal regions of the phase diagram. Two dielectric dispersion steps were found and could be assigned to the intermolecular cooperative dynamics of water at the micellar interface and in the bulk water domains. A quantitative analysis is given. The relaxation amplitudes were used to determine effective hydration numbers. The activation energies of water relaxation were calculated from the relaxation times. The data indicate weaker surfactant-water and water-water interactions near the micellar interface compared to those of bulk liquid water. Further analysis revealed the presence of water clusters large enough to show a cooperative relaxation mode even at high surfactant concentrations. However, the relaxation time of this mode is larger compared to that of pure water. This points out the importance of confinement effects on water dynamics.     

Using molecular dynamics to study liquid phase behavior: simulations of the ternary sodium laurate/sodium oleate/water system

The prediction of surfactant phase behavior has applications in a wide range of areas. An accurate modeling of liquid phase behavior can aid our understanding of colloidal process or be used to design phases that respond in a defined way to their environment. In this work, we use molecular dynamics to model the phase behavior of the ternary sodium laurate/sodium oleate/water system and compare the simulation results to experimental data. Simulations were performed with the GROMOS 53A6 united-atom force field and cover the entire ternary phase diagram, producing micellar, hexagonal, and lamellar phases. The aggregate simulation time for the 33 simulations performed during this study is 4.4 μs. We find that the simulations were able to model the experimentally observed liquid phase behavior accurately, showing that the carboxylate and lipid parameters of the 53A6 force field give very good quality results for the in silico prediction of liquid system phase behavior.     

Studies on the phase properties of lyotropic liquid crystals of Brij35/sodium oleate/oleic acid/water system: By means of polarizing microscope, SAXS, 2H-NMR and rheological methods

The pseudo-quaternary phase diagram of Brij35/sodium oleate/oleic acid/water systems has been investigated, and the liquid crystal area has been identified, which covers about two thirds of the whole phase diagram. The liquid crystal structure and behavior have been also studied by using polarizing texture, small angle X-ray scattering, ²H-NMR and rheometer etc. The result shows that when the composition of the system changes along the line of AA’ in this large liquid crystal region, the structural change is cubic→cubic/lamellar→lamellar→lamellar/hexagonal→hexagonal. Meanwhile, we made the first attempt of systematic study of the rheological properties of the above system. The lattice constants of cubic and hexagonal liquid crystals are 10.53 and 5.68 nm, respectively.     

"Sponge" nanoparticle dispersions in aqueous mixtures of diglycerol monooleate, glycerol dioleate, and polysorbate 80

Lipid nanoparticles of nonlamellar lyotropic phases have a wide solubilizing and encapsulating spectrum for a range of substances thanks to their nanostructured interior featuring both lipophilic and hydrophilic domains. As a consequence, these systems have emerged as promising drug delivery systems in various pharmaceutical and diagnostic applications. Here we present the phase behavior and dispersion properties of a novel three-component lipid system composed of diglycerol monooleate (DGMO), glycerol dioleate (GDO), and polysorbate 80 (P80) which shows several advantageous features relating to drug delivery applications including: spontaneous dispersion formation with a narrow size distribution and tunable particle phase-structure. The obtained phase diagram shows the presence of lamellar (L(alpha)), hexagonal (H(2)), and reverse bicontinuous cubic (V(2)) liquid crystalline phases and an inverse micellar (L(2)) solution. A particularly interesting observation is the presence of a phase region where two liquid phases coexist, most likely the L(2) and L(3) ("sponge phase"). These two phase structures appear also to coexist in the submicron particles formed in the dilute water region, where the L(3) element appears to stabilize nanoparticles with inner L(2) structure. Increasing the fraction of the dispersing P80 component results in the growth of the more water rich L(3) "surface phase" at the expense of the size of the inner L(2) core.     

Aqueous phase behavior of tetraethylene glycol decanoyl ester (C9COE4) and Ether (C10E4) investigated by nuclear magnetic resonance spectroscopic techniques

The binary phase diagram of tetraethylene glycol decanoyl ester (C9COE4) was investigated in the micellar region by PGSE-NMR (pulse field gradient spin echo nuclear magnetic resonance) and in the lamellar liquid crystalline state by 2H NMR. Its behavior was compared to the ether counterpart, tetraethylene glycol decanoyl ether (C10E4), whose phase diagram is well-described. The determination of the self-diffusion coefficient as a function of concentration permitted not only a determination of the critical micellar concentration (cmc) values but also the determination of the size and shape of micelles formed by both compounds. The evolution of the self-diffusion coefficients in the vicinity of the cloud point was also studied, showing no micellar growth with increasing temperature. 2H NMR analyses at the border of and within the liquid crystalline region gave an insight into the lamellar phase structure. We investigated in detail the lamellar phase of both compounds by comparing the values of quadrupolar splittings (Deltanu) measured under the same conditions. Lower Deltanu values were found for the ester compared to the ether: since the ester probably binds more water than the ether, these lower Deltanu values would indicate a lower order parameter in the liquid crystal phase. NMR techniques, either PGSE-NMR or 2H NMR, were confirmed as useful tools to characterize aqueous phase behavior of surfactants, providing supplementary information to the classical techniques such as visual observations, polarized optical microscopy (POM), and surface tension measurements. They also provide a unique insight into the molecular organization in the different phases formed.     

Lyotropic liquid crystalline phases in a ternary system of 1-hexadecyl-3-methylimidazolium chloride/1-decanol/water

Lyotropic liquid crystals formed in a ternary system of 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl), 1-decanol, and water at 25 degrees C are reported. The hexagonal and lamellar phases were characterized by small angle X-ray scattering and polarizing optical microscopy. In the phase diagram, the system shows two isotropic liquid phases, a hexagonal phase connected to the [C16mim]Cl-water axis, and a lamellar phase in the center. The formation of liquid crystalline phases is believed to arise from a hydrogen-bonded network comprised of an imidazolium ring, anion, 1-decanol, and water. In the liquid crystal, the intercalation of 1-decanol between neighboring [C16mim]Cl molecules favors the appearance of lamellar phases. The phase behavior of the present system is discussed in comparison with a similar ternary system of cetyltrimethylammonium bromide (CTAB).