Aliphatic Liquids Research Articles

PH responsive self-assembly and drug release behavior of aliphatic liquid crystal block polycarbonate with pendant cholesteryl groups

An amphiphilic liquid crystal (LC) block copolymer based on aliphatic polycarbonate with pendant cholesteryl groups was synthesized by the coupling reaction. The structure and LC properties of the obtained block copolymer were characterized using FT-IR, 1H NMR, DSC, POM and XRD. The results showed the copolymer exhibited broken focal conic texture and fan-shaped texture of a smectic A phase during the heating and cooling process. Moreover, this copolymer showed mesophase state below body temperature, and it would be promising candidate as self-assembly material for applications in drug delivery. In addition, the self-assembly, drug loading and release behavior of the LC copolymer were investigated with UV–vis, DLS and SEM. It was found that the initial copolymer concentration and the pH value had a critical influence on the self-assembly behavior and the particle size of the micelles. What's more, the drug release also presented a pH response and the drug-loaded copolymer micelles were stable.

Neutron Scattering of Aromatic and Aliphatic Liquids.

Organic solvents, such as cyclohexane, cyclohexene, methylcyclohexane, benzene and toluene, are widely used as both reagents and solvents in industrial processes. Despite the ubiquity of these liquids, the local structures that govern the chemical properties have not been studied extensively. Herein, we report neutron diffraction measurements on liquid cyclohexane, cyclohexene, methylcyclohexane, benzene and toluene at 298 K to obtain a detailed description of the local structure in these compounds. The radial distribution functions of the centres of the molecules, as well as the partial distribution functions for the double bond for cyclohexene and methyl group for methylcyclohexane and toluene have been calculated. Additionally, probability density functions and angular radial distribution functions were extracted to provide a full description of the local structure within the chosen liquids. Structural motifs are discussed and compared for all liquids, referring specifically to the functional group and aromaticity present in the different liquids.

Transport properties of high-density polyethylene/ethylene propylene diene terpolymer blends

Polymer blends based on high-density polyethylene and ethylene propylene diene terpolymer rubber (EPDM) were prepared. The sorption and diffusion of four aliphatic hydrocarbons through the blends were studied in the temperature range of 28–58 °C. Sulfur, dicumyl peroxide (DCP), and a mixture of sulfur and DCP (mixed) were used as cross-linking agents for the blends. Of the three systems, the peroxide vulcanized blends were found to exhibit the lowest penetrant uptake. This has been explained based on the higher rigidity of the –C–C– networks than the polysulfide linkages. The aliphatic liquid penetration through the matrix increased with increase in the EPDM content in the blend. The experimental observations were correlated with the morphology of the blends. Diffusion and permeation coefficients were calculated from the sorption data. A slight deviation from the Fickian trend was observed for the mechanism of transport with an increase in EPDM in the blends. The molar mass between cross-links and thermodynamic parameters of sorption was determined from the swelling data. The experimental observations were compared with various theoretical models.

Nanoconfined liquid aliphatic compounds under external electric fields: roles of headgroup and alkyl chain length

Understanding the structures and dynamics of the confined liquids in nonequilibrium states becomes increasingly important for many practical applications, e.g., nanolubrication and micro/nanofabrication. In the present paper, the effect of external electric fields (EEFs) on several normal straight-chain aliphatic liquids nanoconfined in a ball-plate configuration has been investigated by measuring the dynamic film thickness with the thin film interferometry and calculating the effective viscosity. The results indicate that the EEF effect on promoting the formation of interfacial ordered regions due to dipole orientation and hence affecting the effective viscosity of the confined liquid film is dependent on the type of the headgroup of the molecule. The dipole orientation in the n-alkanol film with a shorter alkyl chain has a larger probability to be affected by EEFs due to the smaller dispersion force and the larger ionic concentration.

Analysis of the effective viscosity of thin interlayers of aliphatic liquids in the fields of fluctuation forces generated by solid substrates

It is established experimentally that the viscosity of micrometer interlayers of mineral motor oil and n-hexadecane between metal substrates differs from the viscosity of the isotropic liquid and depends on the shear strain rate. The observed difference is attributed to the formation of orientation-ordered layers in the field of fluctuation forces of the substrates; the thickness of these layers decreases with the intensity of the flow. The results of viscosimetric experiments are interpreted using a rheological model of a structurally inhomogeneous interlayer with “constant-viscosity” surface layers and an isotropic liquid between these layers. This model is employed for calculating the main structural parameters of such layers and the effect of the flow on them.

Aliphatic Liquid Transport through Heterogeneous Ethylene—Propylene— Diene Monomer Rubber/Poly (ethylene-co-vinyl acetate) Blends

The sorption and diffusion of n-alkanes, namely, hexane, heptane, and octane through crosslinked Ethylene—Propylene—Diene Monomer/ Poly(ethylene-co-vinyl acetate) (EPDM/EVA) blends has been examined in the temperature interval of 28—58°C. Special reference has been given to the effects of blend composition, crosslinking systems, penetrant nature, and temperature on the liquid transport. The solvent uptake was found to decrease with increase in EVA content in the blends. The blends were crosslinked by three crosslinking systems namely, sulfur, dicumyl peroxide (DCP), and a mixture consisting of sulfur and peroxide. The DCP crosslinked system exhibited the lowest solvent uptake. These observations have been correlated with the phase morphology of the blends using scanning electron micrographs. The values of the kinetic parameters of permeability and molar mass between crosslinks have been found to be complementary to the observations. The experimental diffusivity values have been compared with different theoretical models.

Molecular transport of aliphatic hydrocarbons through styrene butadiene rubber/ethylene vinyl acetate blends

AbstractPolymer blends based on styrene butadiene rubber and ethylene vinyl acetate (EVA) were prepared. The sorption and diffusion of four aliphatic hydrocarbons through the blends were investigated with temperatures of 26–56°C. Sulfur, dicumyl peroxide (DCP), and a mixed system consisting of sulfur and DCP (mixed) were used as crosslinking agents for the blends. Of the three systems, the peroxide vulcanized blends were found to exhibit the lowest penetrant uptake. The aliphatic liquid penetration through the matrix decreased with an increase in the EVA content in the blends, which was attributed to the semicrystalline nature of the EVA matrix. The experimental observations were correlated with the morphology of the blends. Diffusion and permeation coefficients were calculated from the sorption data. A slight deviation from the Fickian trend was observed for the mechanism of transport with an increase in the EVA content in the blends. The molecular mass between crosslinks and thermodynamic parameters of sorption were determined from swelling data. The experimental observations were compared with different theoretical models. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2884–2897, 2006

Nanoliter segment formation in micro fluid devices for chemical and biological micro serial flow processes in dependence on flow rate and viscosity

Micro segmentation of liquids inside micro channels and micro tubes opens an easy way for highly parallelized chemical, biochemical and microbiological processes. The production of liquid segments can be done as a fast serial process and leads to a linear arrangement of samples, which are always individually characterized by their position. The segment formation is a function of injector geometry, interface forces, viscosity of the carrier liquid and flow rate. The formation of droplets inside channels of about 500 μm diameter was investigated. Therefore, a micro module made by polymethyl-methacrylate (PMMA) was used for segmentation and integrated in a modular micro fluid arrangement. Microscopic imaging controlled fluidic processes. The inert aliphatic liquid tetradecane and a mineral oil were used as embedding liquids. Segmentation occurred in aqueous solutions of the cationic triphenylmethane dye Malachite Green. The influence of the flow rate on the segment volumes was found to be strongly dependent on the viscosity of the embedding liquid. Operations with series of segments in serial processes as well as possible applications are discussed.

The effect of inorganic and organic chlorine on formation of highly chlorinated organic compounds during incineration: Laboratory pilot study

Aliphatic liquid as a basic fuel was incinerated in a laboratory scale pilot plant. Inorganic chlorine and organic chlorine mixed with basic fuel were used as additive chemicals. Sodium chloride (NaCl) and tetrachloroethylene (C 2Cl 4) were used as the sources of inorganic and organic chlorine. Combustion parameters were adjusted for optimum combustion and, consequently, the amount of particles in flue gases was low. The concentrations of chlorine in flue gases were high enough for possible formation reactions of organic chlorinated compounds in all of the chlorine input tests. An increase in chlorine input did not significantly increase the amounts of highly chlorinated organic compounds, like PCDD/Fs. The main result was that chlorophenol concentrations increased in parallel with organic chlorine input. Comparing organic chlorine to inorganic chlorine tests showed that more highly substituted PCDD/F congeners were formed when organic chlorine was the additive chlorine source. The formation of highly chlorinated organic compounds such as PCDD/Fs requires not only chlorine and aliphatic fuel to be formed, but some catalysts are also needed.

ChemInform Abstract: Aliphatic Liquid Crystals. Part 9. Stereospecific Reduction of 1‐Acyl‐ to 1‐Alkyl‐4‐phenylcyclohexanes.

AbstractThe trans‐ and cis‐acylcyclohexanes (IV) and (V) are prepared from the ketone (I).

ChemInform Abstract: Aliphatic Liquid Crystals. Part 8. Bi‐ and Tercyclohexyl Derivatives by Claisen Rearrangement.

AbstractThe trans‐cyclohexenols (I) are converted to the enamines (VII) via Claisen rearrangement of the acrylic esters (III).

ChemInform Abstract: Aliphatic Liquid Crystals. Part 7. Some Mesogenic Tercyclohexyl Derivatives.

AbstractThe ketone (I) undergoes Horner‐Wadsworth‐Emmons reaction to give (III), which is hydrolyzed to the isomers (IV) and (V).

ChemInform Abstract: Aliphatic Liquid Crystals. Part 5. The Influence of Angular 4a‐ and 8a‐Methyl Groups on the Nematic Character of all‐trans‐Perhydro‐2‐phenanthrenol Esters.

AbstractAusgehend vom Ketal (I) wird über die angegebenen Stufen das Methyl‐perhydrophenanthrenol (IVa) synthetisiert, das in die Ester (IVb) übergeführt wird.

ChemInform Abstract: Aliphatic Liquid Crystals. Part 6. Cholesteric 19‐Norcholesteryl Esters.

Abstract19‐Norcholesterol (Vb) is prepared by a known route via the intermediates (II), (III), (IVa), (IVb), and (Va) and esterified to yield 14 aliphatic and 3 aromatic esters (VII).

Anisotropic Dispersion Interactions In Liquid Crystals

Abstract The polarizability and shape anisotropics of a new class of aliphatic liquid crystals, 4,4′-di-n-alkyl-bibicyclo[2.2.2]octanes (n, n-BBCO) have been calculated as a function of the alkyl chain length and its degree of flexibility to inquire about the relative importance of attractive and repulsive interactions in stabilizing the liquid crystalline phase. The calculated polarizability anisotropics are found to be much smaller than that of conventional mesogens. In the context of the Maier-Saupe theory, this indicates that anisotropic dispersion interactions make only a minor contribution to the stability of this class of liquid crystals. The cylindrical symmetry exhibited by the n, n-BBCO homologues and their rigid molecular structure suggest that they might be ideally suited for critical testing of existing theories of the nematic-isotropic phase transition.

Trans-Cyclohexyl trans-Cyclohexylmethyl Ethers a New Class of Aliphatic Liquid Crystals

Abstract The mesomorphic properties of trans-4-n-al-kylcyclohexyle- and 4-(trans-4-n-alkyclohexyl) phenyl trans-4-n-alkylcyclohexylmethl ethers are briefly described. Although they exhibit lower clearing points and a greater tendency to form smectic phases than the corresponding esters, they are expected to possess both lower viscosities and lower birefringence. The dialkyl derivative melts at a low temperature and exhibits enantitropic smectic and nematic phases.

Repair of a Side Chair with Perforated Plywood Seat

The repair of a mahogany side chair with a perforated, bent plywood seat is detailed.Broken fragments of the seat were rejoined by pushing the parts up into a tentlike formation and pressing them down so that the fractures would mesh. Based on six specific requirements of the adhesive needed for this repair, a survey of over 300 different glues was conducted, and a list of some 40 possibilities was established. After tests were made to determine the rate of shrinkage, an aliphatic liquid glue was injected into the fractures flexed into place. The voids in the seat were filled with thin pieces of plywood of which the top ply was replaced with mahogany veneer, which was fitted and glued in. The replacements were stained, finished with shellac and rubbed down with paraffin oil. Many small lacunae were filled with a colored synthetic wax. A perforated plywood support, a former repair, was removed from beneath the seat, but the underside of the chair was left as found.

Measurement of thermal conductivities of organic aliphatic liquids by an absolute unsteady-state method

Experimental results in the temperature range from −100° to +200°C of 43 fluids ( n-paraffins, n-alcohols, n-fatty acids, n-ketones, n-aldehydes and n-ethers) are presented. The systematic change of conductivity with temperature (or density) and molecular weight in homologous series is shown.

Note on x-ray diffraction in some long chain aliphatic liquids

Summary Alcohols and fatty acids show a more conspicuous “inner ring” than other normal long chain aliphatic compounds.