Surface properties wettability

The problem of spontaneous separation of micromixer-produced droplets was investigated using dodecane and water as the model system [33]. To enhance spontaneous separation the emulsion from the micromixer was fed into a rectangular channel fabricated from aluminum foil as a spacer between two flat plates of glass and/or PTFE. In the case of PTFE coalescence occurred readily whereas glass did not promote the separation. This study demonstrated that the wall material and its surface properties (wettability) can have a big influence on coalescence behavior. 

Nuclear Magnetic Resonance (NMR). The surface sensitive nature of proton NMR relaxation provides a technique for qualitative wettability measurement in porous media. NMR measures the behavior of the magnetic dipoles of hydrogen nuclei in the presence of an applied magnetic field. Proton relaxation rates are strongly dependent upon the pore size and surface properties (wettability) of the pore wall. Water molecules near a water-wet surface will relax faster than near an oil-wet surface (and vice versa for oil). Most efforts to utilize NMR for core wettability have not demonstrated the capability to provide quantitative measures of wettability. However, Howard et al. [3 J ] used relaxation time populations generated by a non-linear optimization technique to distinguish between water and hydrocarbon phases in chalk at various water... 

Coating polymers with inorganic materials is now a well-established practice to achieve radical changes in surface properties (wettability, antistatit conduction, surface hardness) and hulk properties such as the gas-harrier property. RBS provides a convenient and usually accurate means to characterize the thickness of such films, especially when their lack of transparency makes optical characterization impossible. This is an important thickness range to he ahle to characterize accurately, as it typically spans the percolation threshold for ultrathin metallic coatings on polymers. ... 

The surface oxide groups on carbon play a major role in its surface properties for example, the wettability in aqueous electrolytes, work function, and pH in water are strongly affected by the presence of surface groups on the carbonaceous material. Typically, the wettability of carbon... 

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. 

Radiation Treatment NVP, 2-hydroxyethylmethacrylate (HEMA), and acrylamide (AAm) have been grafted to the surface of ethylene-propylene-diene monomer (EPDM) rubber vulcanizates using the radiation method (from a Co 7 source) to alter surface properties such as wettability and therefore biocompatibility [197]. Poncin-Epaillard et al. [198] have reported the modification of isotactic PP surface by EB and grafting of AA onto the activated polymer. Radiation-induced grafting of acrylamide onto PE is very important... 

We therefore have qualitative evidence for the dependence of the dewetting speed on the elastic properties of the substrate. Dependence of wetting on the elastic modulus was previously suggested in the case of thin substrates [31], It may be conjectured that cross-linking affects the surface properties of the elastomer and, therefore, wettability. However,... 

Surface properties such as the absorptional ability and the wettability of minerals are again of significant technical importance. On the wettability scale, as for example, minerals are classified as hydrophilic minerals (which are easily wetted by water) and hydrophobic minerals (which are not wetted by water). Hydrophobicity is very helpful in obtaining enrichment of ores by flotation. 

The surface properties as studied by contact angle measurement are not affected much by the composition of reacting solution so far the solvent is the same. Wettability of all samples plotted in Figures 2 and 3 depends merely on the total amount of graft polymer and the contact angle - IR absorbance plots fall on the same line as shown in Figure 7. 

As we shall see in the present chapter, it is generally the sitoation that a number of specific surface properties govern boundary conditions, and these have been considered extensively in the literature. These include, but are not limited to, wettability and substrate-liquid affinity [1-15], hydrodynamic shear rate [16-20], surface topology and roughness [21-29], and surface material properties [30-36]. 

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. - ... 

Amylose brushes (a layer consisting of polymer chains dangling in a solvent with one end attached to a surface is frequently referred to as a polymer brush) on spherical and planar surfaces can have several advantageous uses, such as detoxification of surfaces etc. The modification of surfaces with thin polymer films is widely used to tailor surface properties such as wettability, biocompatibility, corrosion resistance, and friction [142-144]. The advantage of polymer brushes over other surface modification methods like self-assembled monolayers is their mechanical and chemical robustness, coupled with a high degree of synthetic flexibility towards the introduction of a variety of functional groups. 

The increasing demand for synthetic biomaterials, especially polymers, is mainly due to their availability in a wide variety of chemical compositions and physical properties, their ease of fabrication into complex shapes and structures, and their easily tailored surface chemistries. Although the physical and mechanical performance of most synthetic biomaterials can meet or even exceed that of natural tissue (see Table 5.15), they are often rejected by a number of adverse effects, including the promotion of thrombosis, inflammation, and infection. As described in Section 5.5, biocompatibility is believed to be strongly influenced, if not dictated, by a layer of host proteins and cells spontaneously adsorbed to the surfaces upon their implantation. Thus, surface properties of biomaterials, such as chemistry, wettability, domain structure, and morphology, play an important role in the success of their applications. 

In the process of plasma polymerization, a highly crosslinked polymer is deposited on the surface The deposited plasma polymer changes the surface properties of the substrate dramatically. It modifies the surface of powders in terms of surface energy, functional groups, wettability, interaction with polymers, and dispersion... 

Plasma oxidation of fibers is an example of a treatment aimed at chemically modifying the surface to improve a surface property. These treatments have wide application in industry and are used to improve wettability and printability of plastics, the adhesion of materials to surfaces including tissue culture cells, and a variety of other applications (36). 

The next four chapters provide an introduction to the concepts and techniques needed to study and understand dispersion stability. Some approaches to the characterization of emulsions, foams and suspensions, and of their dispersed species (droplets, bubbles and particles)are described in Chapter 2. The concepts of surface tension, wettability and surface activity, which are important to the stability and properties of all types of dispersion, are described in Chapter 3. To this is added the nature of electrically charged surfaces in Chapter 4. All of these aspects are brought together in Chapter 5 in an introduction to the stability of dispersions. 

Froth flotation is an application of foams that is used to separate mineral components from each other based on their having different surface properties, typically their wettability and surface electrical charge. For example, froth flotation is the classic process used to separate copper from lead ore. The process involves having hydrophobic particles attach to gas bubbles which rise through a turbulent suspension to create a surface foam called a froth. Figure 10.2 shows an illustration of a mechanical flotation cell. This is the classic flotation device [53,91,625], First, the flotation feed particles are well dispersed into a particle suspension. Together with chemical flotation aids, such as collectors and frothers, this constitutes what is called the flotation pulp. In a mechanical flotation cell, air is fed in the form of fine bubbles and introduced near the impeller (see Figure 10.2). In addition to mechanical flotation cells, there are also pneumatic cells and cyclone flotation cells. Pneumatic... 

The surface and type of selected immobilization method will affect the bioactivity, the concentration, and the target-binding ability of bound probe molecules. Gold and glass substrates are good candidates for the immobilization of biomolecules. These substrates have a number of favorable characteristics (1) they are chemically homogeneous and stable, (2) surface properties like wettability can be fine-tuned,... 

Surface properties (such as topography and wettability) of bioceramics similar to human bone can be obtained by decreasing the grain size of ceramic formulations into the nanometer regime. Such surface properties must be incorporated into proactive bioceramics for orthopedic and dental applications surface properties similar to those of physiological bone are needed in order to promote select cell interactions that lead to sufficient osseointegration between an orthopedic or... 

On one hand it is investigated how the addition of cationic surfactants affects the pattern collapse of 193 nm photoresist lines. On the other hand, the adsorption of the surfactant on model photoresist surfaces is explored by a variety of surface chemical methods. Of special interest is how the surfactant changes the surface properties of the photoresist as surface potential and wettability. For an optimum modelling of the properties of real photoresist structures, both unexposed photoresists and photoresists that have been UV exposed, baked and developed are studied. 

Compatibility of polymers implies a semi-quantitative measure can be used to predict whether two or more polymers are compatible. The use of one of the semi-quantitative approaches, solubility parameter, was demonstrated by Hughes and Britt (22). It was concluded (8) that one parameter was insufficient to predict the compatibility. In this paper, we now introduce critical surface tension which is determined from the surface properties of a polymer. Though both of these parameters have been related by Gardon (15), we are inclined to use the latter because we can further describe the wettability between two polymers. For instance, by the use of yc, we can predict equally well that compatibility between polystyrene and polybutadiene can be improved if butadiene is... 

Another important property - wettability was followed by SEM analysis on PS/MWCNTs nanocomposite prepared by in-situ bulk-suspension polymerization (54). Figure 8.7 presents a micrograph of fracture surface of the prepared nanocomposite. The picture very clearly evidences that the nanotubes are covered by a thick layer of polystyrene. Parts of original nanotubes can be identified at the end of the fracture noteworthy is also the smaller diameter at the end of tubes. 

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