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11.
A. Jagminas V. Klimas K. Ma?eika N. Bernotas A. Selskis G. Niaura 《Electrochimica acta》2011,56(16):464
The thick bi-layered gel-like film has been grown by anodizing iron in a novel electrolyte composition based on dimethyl sulfoxide and silica hexafluoride acid (H2SiF6) and examined. The thickness of the anodic film composed of the inner orange-colored nanoporous layer and the outer cherry-colored gel-like layer increased at a constant rate up to 40–50 μm depending on the bath composition and anodizing conditions. Under drying and subsequently annealing, the gel layer shrinks and cracks producing hierarchical morphology of thick films mainly composed of hematite (a-Fe2O3). Scanning electron microscopy, Mössbauer, Raman and energy dispersive X-ray spectroscopies, and X-ray diffraction have been applied to reveal the composition and morphology of these novel films before and following various post-treatments. 相似文献
12.
Understanding the relationship between the molecular structure and the macroscopic properties of polymer solutions and gels, oil-water-surfactant emulsions, lyotropic and thermotropic liquid crystals, colloidal dispersions, detergents, and other such “microstructured fluids” is essential to the optimal use of these commercially important materials. Modern rapid-freezing methods followed by freeze-fracture replication techniques are ideally suited to allow the direct visualization of the three-dimensional structure of the particles or units that make up the dispersion, while simultaneously revealing their orientation and distribution with molecular resolution. This paper reviews the necessary experimental conditions required to successfully exploit the freeze-fracture technique as it applies to microstructured fluid systems. The benefits and limitations of structural studies by freeze-fracture techniques as opposed to the more commonly used light, X-ray, and neutron-scattering methods are discussed. Freeze-fracture replicas can also be imaged by scanning tunneling microscopy to reveal directly three-dimensional fracture contours with improved resolution. 相似文献
13.
Layered and homogeneous gelatin gels with controlled rheological properties were compared for their sensory characteristics, specifically sweetness, hardness, breakdown behaviour and frothing. All gels and layers had a gelatin/water concentration of 5%. The total sugar concentration was 9% in the layered samples and 0, 9, 15 or 22.5% in the homogeneous samples. These concentrations corresponded to the concentrations in the single layers.A seven-layered sample with different sugar concentrations in the layers gave a higher early sweetness intensity than a homogeneous gel with the same mean total sugar concentration. All layered gels were similar in hardness, breakdown behaviour and frothing; for the homogenous samples, sensory hardness was decreased in samples with much sugar. These gels also fell into smaller pieces than the sugarless sample. This study shows that it is possible by controlling the sugar distribution within a sample to produce sweeter gels while the sugar content is maintained. 相似文献
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W. H. Binder L. Petraru T. Roth P. W. Groh V. Pálfi S. Keki B. Ivan 《Advanced functional materials》2007,17(8):1317-1326
Supramolecular gels consisting of trivalent polyisobutylene and bivalent poly(ethylene oxide) are generated. Strong hydrogen bonding interactions, affixed to the end‐group moieties of the respective polymers (binding constant Kassn = 105 M –1), serve as molecular glue, leading to the formation of weak gels. Two different gels were prepared: one, with a short telechelic poly(ethylene glycol) (PEG) segment (gel A), and one with a longer PEG segment (number‐average molecular weight Mn = 2000 g mol–1) (gel B). Both gels show a significant increase in viscosity upon mixing of the two polymeric components, with a lag time of several minutes, indicative of nucleation mechanisms as the formation principle. However, only gel A displays classical gel‐like behavior, with a loss modulus G′ larger than the storage modulus G″ after formation. Both gels display microphase‐separated behavior with a spacing between 4–5 nm as probed via small‐angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. The incorporation of magnetic nanoparticles (Fe2O3; radius r = 3.5 nm) is successfully achieved, generating new magnetic gels with strongly thermoresponsive properties, displaying a strong temperature‐dependent release profile of included dye molecules. Magnetic measurements indicate a superparamagnetic behavior of the incorporated nanoparticles, prospecting the application as magneto‐sensitive delivery gels for pharmaceutical purposes. 相似文献
17.
Saúl VallejosAuthor VitaePedro EstévezAuthor Vitae Saturnino IbeasAuthor VitaeAsunción MuñozAuthor Vitae Félix C. GarcíaAuthor VitaeFelipe SernaAuthor Vitae José M. GarcíaAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(2):686-690
This paper describes the preparation of a hydrophilic copolymer membrane with two comonomers: 1-vinyl-2-pyrrolidone (commercial) and a new water insoluble piperazinedione derivative, which is a fluorogenic mercury sensing motif. The dense membrane permitted the fluorogenic detection of Hg2+ in aqueous media. The sensitivity of the membrane this cation was significantly high, with a detection limit of 10 ppt. This limit of detection is much lower than that of DMSO/water solutions of the sensing monomer, which is 10 ppb, and significantly lower than the maximum contaminant level (EPA) in drinking water, 2 ppb. 相似文献
18.
Irving R. Schmolka 《Journal of the American Oil Chemists' Society》1991,68(3):206-209
The aqueous gel forming properties of three series of block copolymer surfactants, poloxamers, poloxamines, and Butronic® polyols, are briefly reviewed and compared. The differences in their gel formation properties are explained. Aqueous gel formation of these polymers is attributed to the aggregation of extended linear coil micelles in which the hydrophilic ends become entangled as the temperature rises, due to dehydration. The failure of the Butronic polyol gels to exhibit the same reverse thermal behavior shown by the other two polyol series is attributed to a more lipophilic hydrophobe and to the larger number of moles of water associated with the Butronic hydrophile. The reverse thermal characteristics of aqueous poloxamer and poloxamine solutions has led to the development of aerosol detergent systems which can form foamy gels, thereby expanding the usefulness of these surfactants. 相似文献
19.
孔隙阻力因子法评价胶态分散凝胶 总被引:20,自引:9,他引:11
本文介绍了一种类似岩心流动装置的填砂滤管实验装置,在该装置上参照测定转变压力的实验方法测定胶态分解凝胶的孔隙阻力因子Fpr,作为表征凝胶相对强度的新参数。测得的孔隙阻力因子值与转变压力值,TGU值之间有良好的线性相关性,以孔隙阻力因子对时间作图可以求得成胶时间。 相似文献
20.
有机锆交联剂OZ—1应用研究 总被引:5,自引:0,他引:5
合成了具有延迟交联特性的有机锆交联剂OZ1;介绍了OZ1交联的已在胜利油田应用的3种压裂液的性能;探讨了OZ1在水基聚合物冻胶堵剂和弱凝胶或胶态分散凝胶中的应用。 相似文献