Surface and interfacial properties

The van der Waals and other non-covalent interactions are universally present in any adhesive bond, and the contribution of these forces is quantified in terms of two material properties, namely, the surface and interfacial energies. The surface and interfacial energies are macroscopic intrinsic material properties. The surface energy of a material, y, is the energy required to create a unit area of the surface of a material in a thermodynamically reversible manner. As per the definition of Dupre [14], the surface and interfacial properties determine the intrinsic or thermodynamic work of adhesion, W, of an interface. For two identical surfaces in contact ... 

It has been also shown that when a thin polymer film is directly coated onto a substrate with a low modulus ( < 10 MPa), if the contact radius to layer thickness ratio is large (afh> 20), the surface layer will make a negligible contribution to the stiffness of the system and the layered solid system acts as a homogeneous half-space of substrate material while the surface and interfacial properties are governed by those of the layer [32,33]. The extension of the JKR theory to such layered bodies has two important implications. Firstly, hard and opaque materials can be coated on soft and clear substrates which deform more readily by small surface forces. Secondly, viscoelastic materials can be coated on soft elastic substrates, thereby reducing their time-dependent effects. 

One of the most obvious properties of a disperse system is the vast interfacial area that exists between the dispersed phase and the dispersion medium [48-50]. When considering the surface and interfacial properties of the dispersed particles, two factors must be taken into account the first relates to an increase in the surface free energy as the particle size is reduced and the specific surface increased the second deals with the presence of an electrical charge on the particle surface. This section covers the basic theoretical concepts related to interfacial phenomena and the characteristics of colloids that are fundamental to an understanding of the behavior of any disperse systems having larger dispersed phases. 

Andrade, I. D., ed. Surface and interfacial properties of biomedical polymers, vol. 1, New York Plenum Press 1985. 

In several previous papers, the possible existence of thermal anomalies was suggested on the basis of such properties as the density of water, specific heat, viscosity, dielectric constant, transverse proton spin relaxation time, index of refraction, infrared absorption, and others. Furthermore, based on other published data, we have suggested the existence of kinks in the properties of many aqueous solutions of both electrolytes and nonelectrolytes. Thus, solubility anomalies have been demonstrated repeatedly as have anomalies in such diverse properties as partial molal volumes of the alkali halides, in specific optical rotation for a number of reducing sugars, and in some kinetic data. Anomalies have also been demonstrated in a surface and interfacial properties of aqueous systems ranging from the surface tension of pure water to interfacial tensions (such as between n-hexane or n-decane and water) and in the surface tension and surface potentials of aqueous solutions. Further, anomalies have been observed in solid-water interface properties, such as the zeta potential and other interfacial parameters. 

Particles can either be produced by bottom-up processes (e.g. precipitation) or top-down approaches (e.g. wet milling). In these processes particle-particle interactions become relevant when the particle size is below 1 pm. Engineering macroscopic product properties is then only possible through tailored surface and interfacial properties, no matter whether a bottom-up process like precipitation [11] or a top-down process such as milling in stirred media mills [12] is studied. Aggregation is an important aspect in both processes which are studied in the following. 

Compared with other surface and interfacial properties, surface and interfacial tensions have not received much attention in the area of suspensions. In fact it is quite common in industrial practice, when dealing with such systems, to remove the solids and measure and report surface and interfacial tensions on a solids-free basis. This is in spite of the fact that it may be the properties of the suspensions proper that are important. For example, dispersed fine solids can themselves influence surface and interfacial tensions [139]. 

Owen MJ, "Surface and Interfacial Properties" In Mark JE (Ed), "Physical Properties of Polymers Handbook", AIP Press, Woodbury, NY, 1996, Ch 48. 

Hodkin EN, Nicholas MG (1977) Surface and interfacial properties of non-stoichiometric uranium dioxide. J Nucl Mater 67 171... 

Carbon black is produced industrially in the form of different products (e.g., furnace black, thermal black, channel black, lampblack, acetylene black) with specific properties. In addition to the relevance of carbon black for basic research on adsorption, or as a reference sohd, appUcations of this material in fields such as elastomer reinforcement, as modifier of certain properties of plastics (UV protection, electrical conductance, color), or as xerographic toners make its surface and interfacial properties extremely important. Soot is a randomly formed particulate material similar in nature to carbon black. The main (pragmatic, rather than conceptual) difference between these two carbon forms is that soot is generally formed as an unwanted by-product of incomplete combustion of pyrolysis, whereas carbon black is produced under strictly controlled conditions. Bansal and Donnet [78] have reviewed various possible mechanisms for the formation of soot and carbon black. Soot can retain a number of tars and resins on its surface. There is therefore some interest in studying the adsorption of polyaromatic hydrocarbons in soots, especially those of environmental significance such as diesel soot. 

A property referred to the interface between a given pure phase and its vapor is denoted by a single subscript. When the property refers to the interface between two phases, a double subscript is used. Either of the liquid phase components can, by adsorption from the vapor, modify the surface properties of the other liquid or of the solid. In similar fashion, adsorption from one of the liquid phases, when it is saturated with the other liquid, can modify the solid-liquid interfacial properties of that liquid. The surface and interfacial properties so modified are denoted by a subscripted comma, followed by 1 or 2, denoting the component adsorbed. 

Based on these three criteria, more than two hundred polymers were chosen for inclusion in this work. The properties presented for each polymer include some of great current interest, such as surface and interfacial properties, pyrolyzability, electrical conductivity, nonlinear optical properties, and electroluminescence. Not aU the properties are available for all the polymers included, and some properties may not even be relevant for certain polymer classes. Some polymers exhibit properties shown by few others—such as electrolununescence—and those have been presented as "Properties of Special Interest."... 

Thomas Russell is Silvio O. Conte Distinguished Professor, Polymer Science and Engineering Department Director, Energy Frontier Research Center (EFRC), Polymer-Based Materials for Harvesting Solar Energy. His research interests are polymer-based nanoscopic structures, polymer-based nanoparticle assemblies, electrohydrodynamic instabilities in thin polymer films, surface and interfacial properties of polymers, polymer morphology kinetics of phase transitions, and supercritical fluid/polymer interactions. 

Study of the Surface and Interfacial Properties of a Layered MgO/NiO Film. 

Every attempt has been made to include modem topics not covered in a convenient handbook format elsewhere, such as scaling and fractal dimensions, computational parameters, rotational isomeric state models, liquid-crystalline polymers, medical applications, biodegradability, surface and interfacial properties, microUthography, supercritical fluids, pyrolyzabil-ity, electrical conductivity, nonlinear optical properties, and electroluminescence. 

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