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Low Surface Tension (low + surface_tension)
Selected AbstractsParticle-Stabilized Materials: Dry Oils and (Polymerized) Non-Aqueous FoamsADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Ryo Murakami Abstract Oil (liquids with low surface tension and practically immiscible with water) drops can be dispersed in air if relatively oleophobic particles are available. However, such particles with oil-repellent surfaces cannot simply be prepared by controlling the particle surface chemistry alone. Herein the preparation of oil-in-air materials (oil marbles, dry oils) by changing the wetting behavior of particles by tuning the oil properties, which allows the formation of the metastable Cassie,Baxter wetting state of particle assemblies on oil drop surfaces, is presented. The oil-in-air materials can be converted to air-in-oil materials (non-aqueous foams) by tailoring the oil properties, as the robustness of the metastable Cassie,Baxter state of the particle assemblies critically depends on the particle wettability. This conversion implies the phase inversion of dispersed systems consisting of air and oils. It is also shown that particle-stabilized non-aqueous foams can be utilized as template to produce macroporous polymers. [source] Adhesion properties and thermal degradation of silicone rubberJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2007Eung-Soo Kim Abstract Silicone rubber is suitable for the thermal insulator of the rocket motors owing to its heat resisting properties as well as its excellent elasticity and restoring force. However, the adhesion properties of the silicone rubber should be improved greatly to be used as the thermal insulator because of its poor adhesiveness coming from the low surface tension. Functional groups were incorporated through copolymerization to the silicone rubber to induce chemical reaction with the functional groups in the propellant/liner components to enhance the adhesion properties. Peeling tests results disclosed that the incorporation of amine groups was the most efficient for the adhesiveness enhancement and that addition of carbon black improved the adhesiveness still more. Stability against thermal degradation of the silicone rubber was examined by measuring the activation energy through the thermogravimetric analysis. The results revealed that the compounding of the Cloisite® clays boosted up the thermal stability of the silicone rubber much more greatly than that of carbon black. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2782,2787, 2007 [source] Use of perfluorocarbon (fluorinert) to enhance reporter gene expression following intratracheal instillation into the lungs of Balb/c mice: Implications for nebulized delivery of plasmidsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2001Aditya Das Abstract Perfluorocarbons combine high respiratory gas dissolving capabilities with extreme chemical and biological inertness and therefore offer an attractive option as an excipient in the area of pulmonary therapeutics. Perfluorocarbons have also been shown to ,float' mucus, because of their high densities (1.9,2.5 g/mL), which may hold potential in gene delivery for cystic fibrosis patients, in terms of enhancing penetration through highly viscous mucus and thereby providing access to target epithelial cells to correct the gene defect. Additionally, their low surface tension allows for better dispersion. A commonly available perflurocarbon, heptacosafluorotributylamine (Fluorinert), was used to deliver either plasmid DNA (pDNA) alone or cationic-lipid-complexed plasmid DNA to the lungs of Balb/c mice by direct intratracheal instillation. The complexes consisted of supercoiled (SC) plasmid DNA (4.7 Kb, 0.625 mg/mL) and lipid (ethyldimyristoyl phosphatidylcholine [EDMPC]/cholesterol [1:1 mole ratio], with pDNA (3:1 mg pDNA/mM EDMPC in 20 mM Tris-HCl pH 8.0) expressing chloramphenicol acetyl transferase (CAT) or ,-galactosidase (,-Gal). pDNA alone was supplemented with 14% w/v Fluorinert. Cationic lipid/pDNA complexes were supplemented with 3, 8, and 14% w/v Fluorinert. Results showed that the CAT expression from pDNA alone was enhanced 24,× using 14% w/v Fluorinert, whereas that from the cationic-lipid-formulated pDNA was enhanced 7,× using 14% w/v Fluorinert. Immunohistochemistry showed that ,-Gal expression was primarily from epithelial cells and not from F4/80 or MAC3 antigen-stained cells (predominantly macrophages), indicating efficient delivery. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1336,1344, 2001 [source] Polypropylene Hollow Fiber Oxygenators: Effect of the Sorption of PerfluoropolyethersARTIFICIAL ORGANS, Issue 3 2000Flįvia Cassiola Abstract: The introduction of microporous polypropylene hollow fibers in recent years has brought considerable advances to blood oxygenators. However, lifetime and assembly problems are still unresolved. In this work we tried to rate the oxygen permeation velocity by turning the fibers more hydrophobic through the sorption of a perfluorocarbon. Fomblin HC/25, a perfluoropolyether, is well known for its low surface tension and high affinity for oxygen. Celgard X10, X20, and X30 commercial hollow fibers were tested. The hollow fibers showed high affinity for the perfluoropolyether; swelling was clearly shown. A new system for the measurement of oxygen permeation velocity was developed. The oxygen transport velocity was not significantly changed after sorption. The Celgard microporous hollow fibers impregnated with perfluoropolyether showed no water permeation after 2 months of use, reducing one of the most serious problems in the lifetime of these types of fibers. [source] | ||||||||||