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Dynamic Contact Angle (dynamic + contact_angle)
Selected AbstractsCharacterization of spreadability of nonaqueous ethylcellulose gel matrices using dynamic contact angleJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Keat Theng Chow Abstract This study reports the characterization of spreadability of nonaqueous ethylcellulose (EC) gel matrices intended for topical drug delivery using a newly developed method based on dynamic contact angle. EC solutions were prepared using three grades of EC and propylene glycol dicaprylate/dicaprate. Dynamic contact angles of sessile drops of EC solutions on silicone elastomer were measured using a dynamic contact angle analyzer equipped with axisymmetric drop shape analysis-profile. Roughness of silicone elastomer, viscosity of EC solutions and compressibility of semisolid EC gels were determined by the atomic force microscope, cone-and-plate rheometer and tensile tester, respectively. The silicone elastomer employed as a substrate was demonstrated to have similar hydrophilic/lipophilic properties as the human skin. Spreadability of EC solutions was dependent on EC concentration, polymeric chain length and polydispersity. EC gel spreadability was governed by viscosity and the extent of gel-substrate interaction. From the apparent contact angle values, most EC gel formulations tested were found to be moderately spreadable. Linear correlation observed between spreading parameter and compressibility of EC gel verified the applicability of dynamic contact angle to characterize EC gel spreadability. Thus, the feasibility of employing dynamic contact angle as an alternative technique to measure gel spreadability was demonstrated. The spreadability demonstrated by EC gel would facilitate application on the skin indicating its potential usefulness as a topical dosage form. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 3467,3482, 2008 [source] Surface engineering of styrene/PEGylated-fluoroalkyl styrene block copolymer thin filmsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009Elisa Martinelli Abstract A series of diblock copolymers prepared from styrenic monomers was synthesized using atom transfer radical polymerization. One block was derived from styrene, whereas the second block was prepared from a styrene modified with an amphiphilic PEGylated-fluoroalkyl side chain. The surface properties of the resulting polymer films were carefully characterized using dynamic contact angle, XPS, and NEXAFS measurements. The polymer morphology was investigated using atomic force microscope and GISAXS studies. The block copolymers possess surfaces dominated by the fluorinated unit in the dry state and a distinct phase separated microstructure in the thin film. The microstructure of these polymers is strongly influenced by the thin film structure in which it is investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 267,284, 2009 [source] Meniscus deformation and dynamics of moving contact line between poly(ethylene terephthalate) surface and glycerol,water mixturesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Dr Stoyan I. Karakashev Abstract The microscopic hydrodynamic (HD) and macroscopic theories for describing the meniscus deformation and dynamics of a moving contact line have been analyzed and compared by using the extrapolated dynamic contact angles between a poly(ethylene terephthalate) (PET) surface and glycerol,water mixtures. The analysis showed that the microscopic theory is confined by the microscopic length scale and small capillary number. The macroscopic theory is not subjected to any restrictions. Three (inner, intermediate and outer) regions of the dynamic meniscus have been combined by using the contact molecular kinetics and hydrodynamics. The combined molecular-HD theory has been validated using the experimental data for the extrapolated dynamic contact angles between a PET surface and glycerol,water mixtures. The analysis showed that the combined theory describes the phenomenon of wetting qualitatively. It was found that the contradiction within the theoretical framework of the molecular kinetics and hydrodynamics hinders the exact description of the wetting phenomenon. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||