Interfacial characteristics

Zhang J, Manglik RM (2005) Additive adsorption interfacial characteristics of nucleate pool boiling in aqueous surfactant solutions. J Heat Transfer ASME 127 684-690... 

A surface is that part of an object which is in direct contact with its environment and hence, is most affected by it. The surface properties of solid organic polymers have a strong impact on many, if not most, of their apphcations. The properties and structure of these surfaces are, therefore, of utmost importance. The chemical stmcture and thermodynamic state of polymer surfaces are important factors that determine many of their practical characteristics. Examples of properties affected by polymer surface stmcture include adhesion, wettability, friction, coatability, permeability, dyeabil-ity, gloss, corrosion, surface electrostatic charging, cellular recognition, and biocompatibility. Interfacial characteristics of polymer systems control the domain size and the stability of polymer-polymer dispersions, adhesive strength of laminates and composites, cohesive strength of polymer blends, mechanical properties of adhesive joints, etc. 

A. Itaya, T. Yamada, K. Tokuda, and H. Masuhara, Interfacial characteristics of poly(methyl methacrylate) film Aggregation of pyrene and micropolarity revealed by time-resolved total internal reflection fluorescence spectroscopy, Polym. J. 22, 697-704 (1990). 

The interfacial characteristics can be optimized by the application of appropriate coatings to the fiber, allowing desired mechanical properties of the composites to be... 

For example a polymer s interfacial characteristics determine chemical and physical properties such as permeability, wettability, adhesion, friction, wear and biocompatibility. " However polymers frequently lack the optimum surface properties for these applications. Consequently surface modification techniques have become increasingly desirable in technological applications of polymers. - ... 

The spread mixed lipid monolayer studies provide information about the packing and orientation of such molecules at the water interface. These interfacial characteristics affect many other systems. For instance, mixed surfactants are used in froth flotation. The monolayer surface pressure of a pure surfactant is measured after the injection of the second surfactant. From the change in n, the interaction mechanism can be measured. The monolayer method has also been used as a model biological membrane system. In the latter BLM, lipids are found to be mixed with other lipidlike molecules (such as cholesterol). Hence, mixed monolayers of lipids + cholesterol have been found to provide much useful information on BLM. The most important BLM and temperature melting phenomena is the human body temperature regulation. Normal body temperature is 37°C (98°F), at which all BLM function efficiently. 

Rodriguez Nino, M.R., Sanchez, C.C., Rodriguez Patino, J.M. (1999). Interfacial characteristics of (3-casein spread films at the air-water interface. Colloids and Surfaces B Biointerfaces, 12, 161-173. 

Rodriguez Patino, J.M. and Dominguez, M.R. 2000. Interfacial characteristics of diglyceride monolayers at the air/aqueous phase interface. Colloids Surf. A Physicochem. Engin. Aspects 168 35-43. 

Surfactant molecules, as illustrated in Figure 12.2a, are composed of a polar head that is compat ible with water and a nonpolar or hydrophobic hydrocarbon tail that is compatible with oil. This dual nature endows the surfactants with their unique solution and interfacial characteristics. The most noteworthy characteristic is the behavior in dilute aqueous solutions, where the surfactant molecules... 

These synthetic hydrophilic polymers hydrophobically modified can be good systems with which to try to establish relationships between chemical structure and interfacial characteristics. It was determined the surface pressure - area (tt - A) isotherms at the air - water interface for poly(4-vinylpyridine) quaternized as a function of the methylene group number of the alkyl lateral chains (n). The film formation of these polymers on aqueous subphase at constant pH and ionic strength... 

The modification of electrode surfaces with electroactive polymer films provides a means to control interfacial characteristics. With such a capability, one can envisage numerous possible applications, in areas as diverse as electronic devices, sensors, electrocatalysis, energy conversion and storage, electronic displays, and reference electrode systems [1, 2]. With these applications in view, a wide variety of electroactive polymeric materials have been investigated. These include both redox polymers (by which we imply polymers with discrete redox entities distributed along the polymer spine) and conducting polymers (by which we imply polymers with delocalised charge centres on the polymer spine). 

We wished to develop a macroscopic model of the interactions between molecular ligands and receptors. Molecular recognition is a broad subject that describes selective assembly in chemistry and biology, with examples from DNA-protein complex formation to asymmetric catalysis. The principle behind molecular recognition dictates that the molecules that mate have complementary shapes and interfacial characteristics. Our extension of this principle to the mesoscale involved the self-assembly of objects that matched both... 

The results are compared to those above for the CCI4/H2O interface. Several properties of alkane/water and CCU/water interfaces suggest that their interfacial characteristics should be similar. The measured interfacial tensions are 49.7 mN/m for hexane/water and 45 mN/m for CCU/water [73,74], with molecular dipole polarizabilities of 11.9 and 11.2 X 10 cm respectively [75]. However, IR experiments by Conrad and Strauss [76,77] show that water molecules dissolved in an alkane solvent are free to rotate while water dissolved in CCU is relatively constrained. It is the details of these molecular interactions that dominate interfacial structure and dynamics. 

The in-plane rotational correlation time (rrotational correlation time (r) of a fluorophore is expressed as... 

The membrane in a broad sense is a thin layer that separates two distinctively different phases, i.e., gas/gas, gas/liquid, or liquid/liquid. No characteristic requirement, such as polymer, solid, etc., applies to the nature of materials that function as a membrane. A liquid or a dynamically formed interface could also function as a membrane. Although the selective transport through a membrane is an important feature of membranes, it is not necessarily included in the broad definition of the membrane. The overall transport characteristics of a membrane depends on both the transport characteristics of the bulk phase of membrane and the interfacial characteristics between the bulk phase and the contacting phase or phases, including the concentration polarization at the interface. The term membrane is preferentially used for high-throughput membranes, and membranes with very low throughput are often expressed by the term barrier. ... 

The hydrophobicity of the surface prevents the wetting by tear and tends to expose dry surface of a contact lens. Therefore, rapid dehydration of the corneal tissues could occur, which could cause the damage of corneal epithelium. However, this explanation seems to be oversimplified in light of the adsorption of protein, which makes a hydrophobic surface wettable by tear fluid, as described in Chapter 26. Moreover, the highly hydrophobic surface characteristic of silicone rubber tends to encourage the deposition of protein and mucus of the tear on the surface of the lens. Lipids and lipid-soluble materials follow the same track and eventually penetrate into the bulk phase of the contact lens. Because of these undesirable factors, the use of silicone contact lenses of various chemical compositions and with surface treatments has not been successful but rather disastrous because of the interfacial characteristics of silicone contact lens on the cornea, which cannot be oflfset by these efforts. It indicates that more profound surface modification to cope with the problems rather than mere surface treatment is needed in capitalizing on the advantageous bulk properties of silicone polymers. 

The introduction of contact angles gives rise to another interfacial characteristic, the line tension. This is the contractile tension acting in the three-phase contact perimeter around drops as in fig. 1.1, and may phenomenologically be considered the one-dimensioncd analogue of the interfacial tension with SI units of N or J m. As it is a typiccd three-phase characteristic, we shall not treat it here, but in sec. 5.6. 

The interfacial (excess) heat capacity is another Interfacial characteristic that we decided to disregard. The reason for doing so is not in its intrinsic interest. On the contrary, as with bulk heat capacities, they reflect the structure, or ordering (see e.g. FIGS I, sec. 5.3c). However, it is very difficult to establish these values experimentally. Basically the second derivative of the interfacial tension with respect to the temperature at a constant pressure is needed (see sec. 1.2.7), and to obtain this extremely preeise measurements are needed. The spread in the quadratic coefficient B in [1.12.1) indicates the uncertainty, even for a well-studied liquid like water. Yang and Li showed, by a thermodyncimic ancdysis, that for LL interfaces this heat capacity is related to the two bulk heat capacities, the inter-... 

The interfacial characteristics between an oil drop and aqueous mixed emulsifier solutions were studied with a spinning drop interfacial tensiometer. An interfacial layer was observed at the oil/aqueous phase interface, as evidenced by the formation of "tails" on the rotating drop. The length of these "tails" increased with spinning time and rotation speed. The interfacial tensions between styrene and aqueous mixed emulsifier solutions were unexpectedly high, 5 to 13 dynes/cm, whereas tensions in the range of 10 2 dynes/cm were measured between the "tails" and the aqueous solution. 

Source Working media Interfacial characteristics Viscosity ratio a P y K... 

Kulkarni, R.D. and Somasundaran, P., Mineralogical heterogeneity of ore particles and its effects on their interfacial characteristics, Powder Technol., 14, 279, 1976. 

Protein-LMWE interactions at the air-water interface have been studied by tensiometry (Patino et al., 2003). Prom these experiments it has been observed that the interfacial characteristics of mixed proteins and LMWE at air-water interfaces depend at least on the way in which these surface active compounds are adsorbed/spread to the interface (Figure 14.2). 

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