PHASE EQUILIBRIA IN THE SYSTEMS OF ACETIC AND GLYCOLIC ACID WITH WATER AND LAURETH 4

The effect of α-hydroxy group on the phase behavior in a skin lotion model system was studied by determining the phase diagrams for the two systems acetic acid / Laureth 4 / white oil / water and glycolic acid / Laureth 4 / white oil / water using visual observation by optical microscopy. The two acids when combined with surfactant and water gave an isotropic liquid solution, and a lamellar liquid crystal with different amounts of solubilization showing both acids to act as hydrotropes. The result provided essential information about the differences in the phase behavior which can attribute to the presence of a-hydroxy group in the glycolic acid. Small angle x-ray diffraction was used to determine the boundaries of the lamellar liquid crystal phases in the two systems, both acids were found to be located in the water region in the liquid crystal.     

A New System of Multiple Emulsions with Lamellar Gel Phases from Vegetable Oil

Emulsions are excellent pharmaceutical vehicles used in both the pharmacy and cosmetic industries. Vegetable oils have several effects/benefits on skin and can be used in emulsions to release principal active components for cosmetic purposes. Herein, multiple W/O/W emulsions were formulated in a one-step emulsification method, and the resulting anisotropic structures were characterized by x-ray diffraction measurements. The multiple emulsions obtained were stable and maintained their anisotropic structures over 2 years. WAXS (wide-angle x-ray scattering) measurements of these emulsions suggested that the carbon chains of the surfactant around the globules are disposed in a gel network phase. Furthermore, SAXS (small-angle x-ray scattering) measurements indicated that the surfactant is organized in lamellar layers around the globules. Thus, for the first time, we demonstrated that stable lamellar gel phase multiple emulsions can be made from vegetable oils. In addition to having the advantage of being prepared in one step, these emulsions have desirable characteristics that can be used in the cosmetic industry as natural active principles with low surfactant concentration and the unique features of multiple emulsions with gel phases.     

Gelled emulsions with a high water content

The structure of a gel containing 99% water, 0.5% of a nonionic surfactant and 0.5% of a hydrocarbon was investigated by analysis of its equilibrium phases and their state of dispersion by liquid helium freeze fracture electron microscopy.The gel consisted of aqueous droplets of micron size separated by a thin membrane of a lamellar liquid crystal and a W/O microemulsion with droplets varying between 200 and 1000 Å in diameter.     

Dopant-Mediated Interactions in a Lecithin Lamellar Phase

Interactions induced by dopants in a lamellar phase constructed from the lecithin and water are analyzed by the small angle x-ray scattering (SAXS) technique. From SAXS patterns, scattering peak or curve shape changes disclose information on phase structure as well as the interactions between dopant and host matrices. At a certain concentration, two amphiphilic tri-block copolymers (Pluronic P123 and F127) as dopants squeeze themselves into the lecithin bilayers with PPO hydrophobic blocks and produce various effects on the lamellar phase depending on the length of PEO hydrophilic groups. Coexistence of two different lamellar phases is observed in P123-doped systems.     

Experimental electron density distribution of dopamine hydrochloride

Careful high-resolution x-ray diffraction measurements at 90 K have been used to map the electron density distribution in a single crystal of dopamine hydrochloride, a neurotransmitter. A least-squares refinement procedure has been used in which multipole parameters are added to describe the distortions of the atomic electron distributions from spherical symmetry. The refinement also yields improved estimates of the x-ray phases, which have been used to plot maps of the electron distribution. The most electron-rich areas of the molecule are the hydroxyl groups that show large buildups of electron density at the position of the nonbonded lone pairs. The sum of the net atomic charges for the ammonium group is +0.2(2). The net atomic charge for the chloride ion is –0.1(1).     

X-ray scattering intensities of water at extreme pressure and temperature

We have calculated the coherent x-ray scattering intensity of several phases of water under high pressure using the ab initio density functional theory (DFT). Our calculations span the molecular liquid, ice VII, and superionic solid phases, including the recently predicted symmetrically hydrogen bonded region. We compute simulated spectra for ice VII and superionic water. We provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We show that our modified atomic form factors allow for a nearly exact comparison with the total x-ray scattering intensities calculated from DFT. Finally, we analyze the effect of their new form factors have on the determination of the oxygen-oxygen radial distribution function from experiment.     

Solubilization of an Ionic Liquid,l-Butyl-3-methylimidazolium Hexafluorophosphate,in a Surfactant-Water System

The amphiphilic association structures were determined in the system; water, Laureth 4 (approximately C₁₂(EO) ₄), and the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate ([bmim[PF₆]), using visual observation and small angle x-ray diffraction. The system showed a lamellar liquid crystal solubilizing the ionic liquid ([bmim[PF₆]) to a maximum of 15%, an isotropic surfactant solution dissolving the ionic liquid to a maximum of 39%, an isotropic ionic liquid solution with less than 0.5% of water and surfactant and finally, an aqueous solution with only traces of surfactant and ionic liquid. The small angle x-ray diffraction results showed the ionic liquid to be solubilized into the lamellar liquid crystal without changing the dimensions of the amphiphile layer or the interlayer spacing dependence on the water content.     

Conductive polyethylene-carbon black composites by elongational-flow injection molding Part 3. Study of the structure and morphology

The morphology and structure of high molecular weight linear polyethylene (M _w 450000) filled with carbon black and processed using molds that introduce an elongational flow component during injection molding has been examined using electron microscopy and x-ray diffraction techniques. The study of fracture surfaces reveals the display of shish-kebabs oriented along the injection direction with segregated longitudinal channels of carbon black particles. Molecular and lamellar changes in orientation are, furthermore, studied across the thickness of the moldings. It is shown that addition of carbon black particles to injection-molded polyethylene induces significant changes in lamellar orientation. Thus, while lamellar overgrowth proceeds perpendicular to the fiber axes within carbon free channels, lamellae grow randomly within carbon-enriched regions where flow is less pronounced.     

Characterization of structural transitions in the SLS/decanol/water system

The ternary system sodium-dodecylsulphate (SLS)/decanol/water has been investigated at three different water contents and varying ratios of cosurfactant to surfactant by means of polarized optical microscopy,²H-NMR quadrupole splittings and small angle x-ray scattering. Upon addition of decanol a hexagonal phase transforms into a lamellar phase. For the highest water content of 0.65 no intermediate two-phase regions are detected but nematic phases are formed between. The lamellar phase at low cosurfactant content is very sensitive to changes of temperature and seems to be a so-called defective one with curved interfaces. From the scaling behavior it is concluded that the building units seem to be ribbons of increasing width on addition of cosurfactant or amphiphilic substance. By reaching a decanol mole fraction of 0.4 a classical lamellar phase with well-known behavior is formed. During these transformations the position of the first diffraction maximum changes gradually irrespective of phase transitions. The maximum mole fraction of cosurfactant the lamellar phase of our system can incorporate is 0.77.     

Thermotropic and lyotropic phase behaviour of monoalkyl glycosides

We have studied the thermotropic and lyotropic phase behaviour of seven monoalkyl glycosides using polarizing microscopy, differential scanning calorimetry and X-ray diffraction. The phase behaviour of these non-ionic surfactants is compared with that of two previously studied monoalkyl glycosides \[1]. We have found that small modifications in chemical structure can lead to large changes in the phase behaviour. The results reveal the effect of changes in alkyl glycoside chemical structure on the phase behaviour, in particular, on the melting point, the clearing point, the solubility in water, and the extent of the lamellar and curved phases. Seven out of the nine surfactants were found to exhibit thermotropic mesomorphism. Furthermore, in the presence of water, three formed lamellar (L ), type I cubic (Q ) and type I hexagonal (H ) phases, two formed lamellar and cubic phases, and two I I formed only lamellar phases. The cubic phase in each case was indexed, either from powderlike or monodomain samples, as spacegroup I a3 d . The lowest order low angle X-ray spacings were found to lie on single, continuous lines with varying water content across the L , Q and H phases, implying epitaxial relationships between these phases at the phase boundaries. I a a I     

Microstructures of Aqueous Two‐Phase Systems Formed by Mixture of Polymer and Cationic‐Anionic Surfactants

Microstructure and phase behavior of decyltriethylammonium bromide (C₁₀NE)/sodium decylsulfonate (C₁₀SO₃)/poly(ethylene oxide) (PEO)/water quaternary systems were studied by freeze‐fracture transmission electron microscopy, small angle X‐ray diffraction, and dynamic light scattering methods. Aqueous two‐phase systems (ATPS) could be prepared by properly mixing the aqueous solution of PEO and equimolar mixed C₁₀NE and C₁₀SO₃. It was shown that the top phase of the ATPS was surfactant‐enriched and mainly composed of multi‐lamellar structure, while the bottom phase of the ATPS was polymer‐enriched in which some vesicles were observed.     

Orientation control of ferroelectric polymer molecules using contact-mode AFM

We have developed an orientation control technique for polymer molecules utilizing contact-mode atomic force microscopy (AFM). In this technique, the molecular chains were directly modified by scanning an AFM cantilever tip in contact with the film surface at the temperature just below its melting point. We call this process “modification scan”. Here, we applied this technique to poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) thin films on graphite and glass. We prepared a 75-nm thick copolymer crystalline film on graphite whose lamellar plane was perpendicular to the substrate (edge-on), and also prepared a film of the same thickness on glass whose lamellar plane was parallel to the substrate (flat-on). After applying this technique on both films, molecular chains were stretched and aligned to the modification scan direction, and new edge-on crystals were obtained, whose lamellar planes were well-aligned perpendicular to the modification scan direction.     

Changes of mesophase structure of BRIJ 96/water mixtures on addition of liquid paraffin

The influence of the addition of liquid paraffin (LP) on the structure of the lamellar (L ) and hexagonal (H₁) mesophases formed in mixtures of water (W) and BRIJ 96 (B) was studied. Mesophases were identified using polarization microscopy and small angle x-ray diffraction (SAXD). Repeat spacings were also determined with SAXD. Depending on theW/B ratio, addtion ofLP toL gives a large, almost linear one-dimensional swelling or an initial swelling followed by a gradual transition to H₁.L with a highLP-content gives a diffraction pattern showing only the first order diffraction maximum, possibly a result of undulations of the layers. The lamellar structure, however, was confirmed using freeze fracture electron microscopy (FFEM). Addition ofLP to H₁ gives an initial swelling followed by a transition to a transparent, highly viscous, isotropic phase, called the gel-phase (G). The diffraction pattern obtained fromG yields little information on its structure. A large swelling ofG withLP was observed. From the degree of swelling as a function of hydrocarbon content it was inferred that this phase consists of spherical aggregates forming a close-packed structure. Using FFEM, textures were visualized resembling those obtained from the isotropic mesophase (I₁) in water-surfactant mixtures. Finally, geometrical factors are discussed that may play a role in the formation of the gel-phase.     

Solvent induced ordered-supramolecular assembly of highly branched protoporphyrin IX derivative

Protoporphyrin IX species bearing highly branched alkyl chains were self-assembled into well-defined nanostructures such as rod-like in CHCl₃–cylcohexane (1:9, v/v) and a honeycomb-like morphology in a polar solvent dimethyl sulfoxide (DMSO). The rod-like morphologies observed in the atomic force microscopy (AFM) and transmission electron microscopy (TEM) suggest that the lamellar phase self-organises into multilamellar vesicles. The X-ray diffraction (XRD) results indicate molecular arrangements resulting from longitudinal and transverse stacking of the porphyrin head groups in the lamellar structure. The typical nanostructures were derived from a high level of cooperativity between the porphyrin cores via π–σ interactions and supported by hydrogen bonding and van der Waals interactions. The nanostructures were characterised by means of UV–vis, fluorescence, AFM, TEM and XRD analysis. Our methodology confirms the potential of protoporphyrin IX derivatives in supramolecular chemistry.     

辛烷基苯酚聚氧乙烯醚与正癸醇层状液晶的有序性及层状结构

Order character and lamellar structure of TritonX 100/n C10H21OH/H2O lamellar liquid crystal were investigated. Partial phase diagram of TritonX 100/C10H21OH/H2O was measured at 25℃ by the polarizing microscope, and lamellar structure of the lamellar liquid crystal was verified by the 2H NMR spectra. The ESR spin probe method was used to detect the changes in the lamellar liquid crystal. A stearic acid, 5 doxylstearic acid, was used as the spin probe. The values of hyperfine coupling constant and order parameter of lamellar liquid crystal in the phase diagram were calculated. The values of the hyperfine coupling constant with different composition were almost unchanged. It indicates that the micropolarity of the lamellar liquid crystal is very similar. The order parameter decreases with the increasing water content in lamellar liquid crystal. It can be explained by considering that: First, though the penetration is determined at the given weight ratio of C10H21OH to TritonX 100, the absolute water content penetrated into the amphiphile bilayer increases with the increasing of the water content. Second, the thickness of the solvent also increases, which makes the force between layers weaker. The results also showed that order parameter of lamellar liquid crystal increased with TritonX 100 content, which may be explained from the fact that the water content penetrated into the amphiphile bilayer decreases relatively and the molecules in the amphiphile bilayer are made tighten. The interlayer spacing of lamellar liquid crystal was determined by small angle X ray diffraction. The penetration ratio of water in the lamellar liquid crystal was calculated. It was about 50%.     

Orientation and morphology of high-density polyethylene film produced by the tubular blowing method and its relationship to process conditions

The orientation and crystallinity of a series of high-density polyethylene (HDPE) tubular films is characterized using wide-angle x-ray scattering pole-figure analysis and birefringence. The films ranged from uniaxial to equal biaxial. The data were used to compute biaxial orientation factors which were then plotted on an orientation-factor triangle diagram. It was shown, within the range of conditions studied, that both the crystalline biaxial orientation factors were unique functions of the stresses exerted on the bubble at the freeze line. Both correlations are the same as those developed by Dees and Spruiell for melt-spun HDPE fibers. SAXS measurements on the films suggest lamellar structures in both uniaxial and biaxial films.     

Amphiphilic association structures in the system water,vitamin E,lecithin and phosal 75 SA

The main features of the system water, vitamin E, lecithin and Phosal 75 SA was determined using optical microscopy and low angle x-ray diffraction.The results showed the lecithin/water lamellar liquid crystal to be retained when the lecithin was gradually replaced by Phosal 75 SA. The vitamin E was solubilized in the lamellar liquid crystals to a maximum level in the range of 15–20% by weight.The vitamin E intermingled with the amphiphile in the liquid crystal causing only minor structural changes.     

Electrospinning of ultra-thin polymer fibers

The electrospinning technique was used to spin ultra-thin fibers from several polymer/solvent systems. The diameter of the electrospun fibers ranged from 16 nm to 2 μm. The morphology of these fibers was investigated with an atomic force microscope (AFM) and an optical microscope. Polyethylene oxide) (PEO) dissolved in water or chloroform was studied in greater detail. PEO fibers spun from aqueous solution show a “beads on a string” morphology. An AFM study showed that the surface of these fibers is highly ordered. The “beads on a string” morphology can be avoided if PEO is spun from solution in chloroform; the resulting fibers show a lamellar morphology. Polyvinylalcohol (PVA) dissolved in water and cellulose acetate dissolved in acetone were additional polymer/solvent systems which were investigated. Furthermore, the electrospinning process was studied: different experimental lay-outs were tested, electrostatic fields were simulated, and voltage - current characteristics of the electrospinning process were recorded.     

Structural properties of nonionic surfactant/glycerol/paraffin lyotropic liquid crystals

Lamellar lyotropic liquid-crystalline systems are thermodynamically stable, optically isotropic and are formed spontaneously. New possibilities for the development of controlled drug delivery systems are inherent in these systems in consequence of their stability and special, skin-friendly structure. The aim was to formulate and study two-component or multicomponent compositions with a relatively low Brij 96V content, liquid paraffin, glycerol and water for therapeutic purposes. The liquid crystals were examined by polarizing light microscopy and transmission electron microscopic observation of replicas produced by the freeze–fracture technique to demonstrate the presence of lamellar liquid-crystalline domains. The existence of a regular structure was determined by X-ray diffraction.     

Some comments on domain structures in block copolymers

Although samples of amorphous polymers cast from solution are usually assumed to be isotropic, they may, in fact, have some anisotropy due to the Bénard effect, in which the convection currents produced by evaporation are organized into a regular arrangement of cells. A pattern of hexagonal convection cell is easily visible during casting of SBS triblock copolymers. The anisotropy is demonstrated by comparing the small-angle x-ray diffraction diagrams taken through the face and edge of the films. The domain structures in two SBS copolymers are characterized by diffraction measurements. The smallangle diagram of a triblock polymer containing 50% styrene indicated a lamellar structure, while that from a 28% styrene copolymer is interpreted as arising from a hexagonal array of polystyrene cylinders dispersed in a continuous polybutadiene phase. Published diffraction data for block copolymers and other amphiphiles are surveyed in an attempt to place some limitations on the composition ranges over which the various types of domain structure exist. The factors which determine the dimensions of the two domains in lamellar phases formed from diblock copolymers are examined theoretically, and the predicted dimensions are compared with experimental results.