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Amphiphilic Polymers (amphiphilic + polymer)
Selected AbstractsUse of associating polymers as multifunctional thickeners: studies of Their structure in aqueous solutions via nmr, qels, fluorescence, And rheology measurementsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2007Katsunori Yoshida The solution properties of an associating polymer were studied by NMR, quasi-elastic light scattering (QELS), fluorescence, and rheology measurements. An associative thickening (AT) polymer was designed having a nonionic poly(ethylene oxide) backbone with long alkyl chains at both ends to achieve high viscosity even at relatively high salt concentrations and over a wide pH range. This study focuses on the associative state of the polymer in aqueous solutions at various polymer concentrations. In a fluorescence probe study using pyrene a spectral change in the I3/I1 ratio was observed for pyrene at a polymer concentration (Cp) of 3 x 10 -4%, indicating an apparent critical concentration (cmc) of the amphiphilic polymer. The viscosity, self-diffusion coefficient (Dsel), and hydrodynamic size (Rh) distribution measurements at various Cp all suggest that there is a second transition at Cp, 0.4%. Although we observed the discontinuity in viscosity, Dsel, and Rh at Cp, 0.4%, no changes in the relaxation times (T1 and T2) were recognized for either the alkyl chain or the ethylene oxide moiety of the polymer at C p= 0.1,1%. These data suggest that there are no structural changes or phase transitions at Cp, 0.4%, but that intermicellar networks are presumably formed by bridging of the end alkyl groups of the polymer, which is driven by hydrophobic forces. Because the polymer forms networks by hydrophobic interaction and the polymer itself is nonionic, the viscosity of the polymer solution was influenced very little by either the addition of salt or a pH change, as would be expected. The dynamic viscoelastic study revealed that the polymer solution exhibits a single mode Maxwell type relaxation behavior with a terminal relaxation time of about 0.61 s, which imparts a unique flow appearance to the polymer solutions. The time course measurements of the dynamic elastic modulus of the stratum corneum revealed that the polymer has excellent potential for skin softening. It was concluded that the associative thickening polymer not only is a useful thickener with a salt and pH tolerance but also has beneficial skincare effects. [source] Preparation and characterization of quercetin-loaded polymethyl methacrylate microcapsules using a polyol-in-oil-in-polyol emulsion solvent evaporation methodJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2007Dong-Hwan Lee Flavonoids and related compounds exhibit a wide range of useful pharmacological properties but present challenges related to their stability and solubility in commonly available solvents. In this study, polymethyl methacrylate (PMMA) microcapsules were prepared using a novel polyol-in-oil-in-polyol (P/O/P) emulsion solvent evaporation method as a means of stabilizing the flavonoids, using quercetin as a model flavonoid drug. The morphology of the microcapsules was evaluated using a scanning electron microscope, revealing a spherical shape with a smooth surface. The cross-section image of the PMMA microcapsules prepared with an amphiphilic polymer in the inner polyol phase showed that the microcapsule was filled with several submicron microspheres. The mean diameter varied from 1.03 ± 0.12 ,m to 2.39 ± 0.42 ,m, and the encapsulation efficiency ranged from 12.7% to 26.9%. When free quercetin was stored at 42°C, the residual quercetin content gradually decreased to 18% over 28 days as a result of oxidation. However, when encapsulated in PMMA microcapsules with an amphiphilic polymer in the inner polyol phase, the residual quercetin content decreased to just 82%. In-vitro release studies indicated a sustained release pattern throughout the 36-h study. The release kinetics of the microcapsules with an amphiphilic polymer followed a diffusion-controlled mechanism and the microcapsule without amphiphilic polymer followed an anomalous diffusion behaviour. This study suggests that the novel P/O/P emulsion solvent evaporation method can be applied to the encapsulation of flavonoids. [source] Cyclodextrin polyrotaxanes assembled from a molecular construction kit in aqueous solutionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2009Gerhard Wenz Abstract We describe a molecular construction kit in which amphiphilic polymers and functionalized cyclodextrins are arranged into sophisticated molecular architectures in aqueous solution without the need to perform chemical reactions. Therefore, these systems are highly biocompatible and show programmable lifetimes. The kinetic stabilities of our polyrotaxane structures are tunable using sterically demanding groups that hinder dissociation. These cyclodextrin-based polymer systems are applicable in principle for the detection of analytes at the level of single molecules. These systems may also serve well in targeted drug delivery and gene transfection. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6333,6341, 2009 [source] Synthesis and Characterization of Amphiphilic Star-Shaped Polymers With Calix[6]arene CoresMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2006Weipu Zhu Abstract Summary: The syntheses and characterizations of well-defined star-shaped amphiphilic polymers containing a hydrophobic p - tert -butyl-calix[6]arene core and six hydrophilic PPO or PPO- b -PDTC arms are described. The average number of PO units in each arm could be adjusted by choosing a suitable amount of raw material. Schematic structure of the amphiphilic star-shaped block copolymer containing a hydrophobic p - tert -butyl-calix[6]arene core and six PPO- b -PDTC arms. [source] Stimuli-responsive water soluble and amphiphilic polymers,ACS Symposium Series 780 Edited by C,L McCormick American Chemical Society (distributed by Oxford University Press), Washington, 2001 pp xii,+,352, Price $125.00 ISBN 08412 37255POLYMER INTERNATIONAL, Issue 8 2002A Finch No abstract is available for this article. [source] | |||||||||||||