This paper is devoted to the investigation of the relations between cones satisfying the angle property and solid cones. The investigation shows that the two classes of cones are dual in some sense. As an application of our results, we improve some related results due to Cesari, Suryanarayna, Sterna-Karwat, and Yu.This research was supported by the National Natural Science Foundation of China. It was completed while the author was a PhD Student at the Department of Mathematics, Shandong University, Jinan, China. The author would like to thank Professor D. Guo for encouragement. The author is also grateful to the referees for comments and suggestions. 相似文献
Switchable surfaces are highly useful materials with surface properties that change in response to external stimuli. These surfaces can be employed in both research and industrial applications, where the ability to actively control surface properties can be used to develop smart materials and intelligent surfaces. Herein, we review a range of surfaces in which hydrophobicity can be controlled. We present the principal ideas of surface switching, discuss recent developments, explore experimental issues and examine factors that influence surface switching, including the nature of the stimuli, the underlying material, the morphology of the surface and the surrounding environment. We have categorised switchable surfaces according to the stimuli that trigger changes in surface hydrophobicity. These are electrically, electrochemically, thermally, mechanically, photo- and environmentally inducible surfaces. In addition, we review the use of chemical reactions to modify the properties of switchable surfaces and produce changes in the molecular structure and nanoscale features of the surface. 相似文献
Hydrophobic surfaces with adsorbed tri-block copolymers are wetted by oil in spite of the hydrophilic buoy groups of the block copolymer that are present near the surface. The effect of the buoy group length of the adsorbed molecules on the wettability of hydrophobic surfaces is studied by contact angle measurements and by computer modelling.
The computer model predicts an increase in interfacial free energy with increasing buoy group length for equilibrium adsorption of block copolymer from water. Molecules with large buoy groups occupy more lateral space; therefore the “bare” surface gets more exposed and the anchor groups contribute less to the interfacial free energy which thus increases with the buoy group length.
The calculations showed that the variation of the interaction parameter between solvent and buoy group hardly influences the interfacial free energy. In contrast the interaction parameter between solvent and surface influences the interfacial free energy to a large extent because the oil/surface interactions have a lower energetic value as compared to water/surface interactions and therefore the interfacial free energy is lower than in water. The interfacial free energy varies slightly with increasing buoy group length, depending on the value chosen for the solvent/surface interaction parameter.
Advancing and receding contact angles of hexadecane, sunflower oil and hydrolysate (partly hydrolysed sunflower oil) were measured on hydrophobic surfaces. All oil/water contact angles were small, indicating a hydrophobic apolar surface character. It was found that, for oils with a “good” interaction with the surface (hexadecane and sunflower oil), the contact angle has a minimum value at a certain buoy group length. For hydrolysate (less-strong interaction with the surface) the contact angle decreases monotonically with increasing buoy group length. The results for hexadecane, sunflower oil and hydrolysate are in reasonable agreement with the model predictions. The effect of increasing buoy group length is weak; both decreasing and increasing angles are found, depending on the type of oil used. 相似文献
The change of crystal structures in polyethylene terephthalate (PET) and polyhexa methylene terephthalate (PHT) irradiated by γ-ray were investigated by using the methods of WAXD and SAXS. It was found that irradiation caused the crystal parameters of PET and PHT to lengthen, and the cell to expand; and at the same time, the long period and the thickness of lamellae were unchanged. These results indicate that the radiation damage of crystal polyesters causes the increase of lacunaries within the crystal polyester. 相似文献
Summary A systematic investigation on the adsorption and association of inosine at a hanging mercury drop electrode by phase-sensitive ac voltammetry has been performed. The adsorption equilibrium bas been determined as a function of various parameters such aspH, adsorption potential, adsorption time, and bulk concentration of inosine. It was found that the association of the adsorbed species depends predominantly on the stacking interactions of neutral inosine molecules. Over a wide potential range, inosine exhibits a dilute adsorption characteristic where it is adsorbed with the base flat on the electrode surface. Above a certain threshold value, inosine appears to undergo a surface reorientation and adopts a perpendicular position. The nucleation and growth mechanism is analyzed applying theAvrami equation. Characteristic properties and adsorption parameters of dilute and compact layers of inosine were evaluated from the two-stepFrumkin isotherm and from the potential dependence of adsorption.
Oberflächenaktivität und Orientierung von Inosin an einer Quecksilber/Lösungs-Grenzfläche
Zusammenfassung Die Adsorption und Assoziation von Inosin an einer Quecksilbertropfelektrode wurde mittels phasensensitiver AC-Voltammetrie systematisch untersucht. Die Abhängigkeit des Adsorptionsgleichgewichts von Parametern wiepH-Wert, Adsorptionspotential, Adsorptionszeit und Inosinkonzentration wurde gemessen. Dabei zeigte sich, daß die Assoziation der adsorbierten Spezies vorwiegend von der Anordnung und den Wechselwirkungen der neutralen Inosinmoleküle abhängt. Inosin bildet über einen weiten Potentialbereich eine dünne Adsorptionsschicht aus, wobei die Base flach auf der Elektrodenoberfläche aufliegt. Ab einem bestimmten Grenzwert der Konzentration tritt eine Reorientierung zu einer senkrechten Anordnung ein. Keimbildung und Wachstumsmechanismus wurden mittels derAvrami-Gleichung analysiert. Eigenschaften und Adsorptionsparameter der verdünnten und der kompakten Inosinschicht konnten aus der zweistufigenFrumkin-Isotherme und aus der Potentialabhängigkeit der Adsorption bestimmt werden.
Fractions according to the degree of branching of (Ethylene/1-Buten)-Copolymer (LLDPE) were investigated by wide-and small-angle scattering. The thickness of the crystallites is nearly independent of the degree of branching and their volumes reach a limit according to the smallest stable crystal. The mean lattice disfortions also do not change remarkably with the degree of branching but the components of thegik tensors do so. The possibility of partial incorporation of side groups into the crystal lattice is discussed. Comparison of wide-and small-angle scattering shows that only the part of the crystallites with smaller thickness builds lamellar clusters while thicker ones are individual crystals.Dedicated to Prof. Dr. W.Pechhold on the occasion of his 60th birthday 相似文献
In this paper, we report a novel synthesis of poly(ethylene oxide monooleate-block-DL-lactide) (MOPEO-PLA) in the presence of stannous 2-ethylhexanoate catalyst. By utilizing the surfactant property and the reactive double bond of the amphiphilic MOPEO-PLA, various characteristics of PLA microspheres, such as surface and internal structure, surface morphology, release property, and so on, may potentially be controlled. MOPEO-PLA was found to be hydrophobic enough to prevent loss by dissolution into aqueous solution, which is often a problem for MOPEO. Furthermore, the interfacial tension measurements of a MOPEO-PLA/toluene/water system revealed that MOPEO-PLA had a good surface activity almost equal to that of MOPEO. The MOPEO-PLA/PLA blend films were prepared by solvent casting on a water layer. Contact-angle measurements of MOPEO-PLA/PLA blend films confirmed that the hydrophilic PEO segments were selectivity accumulated at the oil/water interface. Moreover, the surface free energy on the 'water side' of the MOPEO-PLA/PLA blend films was increased because of the increase in polar components as a result of the ether bonds of the PEO segments. Schematic illustration of the adsorption property of a) MOPEO-PLA with a high-molecular-weight PLA segment and b) MOPEO-PLA with a low-molecular-weight PLA segment at an ethyl acetate/water interface. 相似文献