Modifying the Interface

According to the colloid scientist Winsor, surfactants are defined as compounds which possess in the same molecule distinct regions of hydrophilic and lipophilic character. For example, in the oleate ion there is an alkyl chain that is basically hydrophobic (lipophilic tail) and a COO" headgroup that is hydrophilic (lipo-phobic). Being amphiphilic in nature, surfactants have the ability to modify the interface between various phases [66]. Their effects on the interface are the result of their ability to orient themselves in accordance with the polarities of the two opposing phases. The polar part can be expected to be oriented towards the more polar (hydrophilic, aqueous) phase, whereas the nonpolar tails should direct towards the nonpolar (lipophilic, oil) phase. 

In principle, interfacial recombination processes can be inhibited by modifying the interface. The use of t-butylpyridine in the DSSC electrolyte solution to increase its photovoltage is one example [2,97]. We wished to explore general methods for passivating interfacial recombination sites in DSSCs that might allow the use of a variety of redox couples and therefore facilitate making a viable solid-state DSSC. 

Additional evidence for the role of the supercritical fluid in modifying the interface is provide in Figure 12. Here the capacity factor for n-pentane on alumina at 40°C is shown as a function of pressure up to 700 atmospheres. The considerable... 

Such kind of considerations about the finite dimensions of the interfacial area at the polymer/mineral interphase must be taken into account when we try to modify the interface by substituting a part (frequently a little part is enough) of the polypropylene matrix with a chemically modified polypropylene by grafting of polar groups. Also, the structural characteristics of such chemically modified polypropylene must be considered, mainly its molecular weight, if crystalline or not, and the nature and number of polar grafts. 

Interparticle forces are a determinant factor for most properties of dispersions, including rheological behavior. They are produced by the molecular forces on the surfaces of the particles, due to their nature or to adsorbed molecules, that modify the interface. These are electrical forces arising from charges on the particles and London-van der Waals attraction forces. The role of these forces on suspension stability has been extensively study and is known as the DLVO theory. In addition, sterical forces encountered on dispersions stabilized with nonionic species also exert an important influence on rheological behavior. The nature of these forces will not be considered since they are matters of discussion in Chapters 1-4. However, from a rheological point of view it is impwtant to understand how these factors modify the flow characteristics of dispersions. 

In the aftermath of the accident. Airbus modified the interface of the autopilot so that a vertical speed setting would be displayed as a four-digit number, preventing confusion with the Hight Path Angle mode. 

Studies by Ravikumar et al. (2005) show that PTT/ethylene propylene diene monomer (EPDM) blends are irrmriscible, which is supported by an increase in the free volume and constancy in crystallinity of PTT with increasing EPDM content and the use of ethylene propylene monomer grafted maleic anhydride as compatibilizer is found to produce significant improvement in properties by modifying the interface of the blends. 

This weakness of the interfaces between most immiscible polymers explains why the mechanical properties of two-phase polymer mixtures are generally so poor. However, as we saw in chapter 6, we can modify the interfaces between immiscible polymers using block copolymers. In section 6 we concentrated on the role of such so-called compatibilisers in lowering the energy of the interface between the immiscible phases. However, in addition to this effect... 

How can my software application be improved to help those with visual impairments Use standard user-interface elements compatible with screen readers. Is the application compatible with screen-magnification and speech-synthesis software Do not require a pointing device and allow the user to modify the interface. For example, can the user select the font style, color, and size What about the background color Do not place time limits on input activities or messages. Do not rely on color alone to convey information. For example, a green-filled circle that becomes red when done may not be seen. ... 

As already mentioned, a microemulsion system can comprise not only a surfactant film separating an oil phase and a water phase (one of them in dispersed form) but also (i) a salt, (ii) a co-surfactant (generally an alcohol) and (iii) other additives like polymers. What are their roles in modifying the interface, and in turn, the capability of uptake of the dispersed phase Caillet etal [126] addressed... 

It is possible to modify the interfaces between liquids with specific additives. This was discovered by andent and medieval investigators and applied in the form of soaps, and later in food technology and in the application of dyes. The mechanisms of these additives only came to be realized in about 1900. Such additives are generally molecules with hydrophobic and hydrophilic sedions that align along interfaces between the two liquid phases. They reduce interfadal tension and stabilize phase morphology to smaller dispersed phase sites. This phenomenon was realized by IG Farbenindustrie chemists who applied it in the late 1920s in emulsion polymerization that they used to produce synthetic rubber. 

These films have also been used to improve the charge transfer efficiency of photovoltaic cells employing solid state electrolyte Polypyrrole was used to modify the interface between n-Si and polyethylene oxide-KI/I solid electrolyte in a thin film photoelectrochemical cell (see Fig. 11). This cell has an open circuit potential of 320 mV when irradiated with 100 mW/cm tungsten-halogen light. The photocurrent response and the stability of the cell was improved by an order of magnitude when the n-Si surface was precoated with 1--2 nm of platinum. 

Ng CM, Manickam S (2013) Improved functionalization and recovery of carboxylated carbon nanotubes using the acoustic cavitation approach. Chem Phys Lett 557 97-101 Nie M, Fisher FT (2013) A nano-hybrid shish kebab approach to modifying the interface in carbon nanotube—semicrystalline polymer nanocomposites. In Proceedings of the 28th annual technical conference of the American society for composites 2013, ASC 2013, vol 2, pp 1804-1814... 

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