Water-organic interface

Chemically Benign Synthesis at Organic-Water Interface... 

Some further examples of syntheses at organic-water interface are ... 

Recently, the concept of an ambidextrous surfactant, which is active at an organic-C02 and organic-water interface, was demonstrated as shown in Figure 8.10. The surfactants included a PDMS block, a poly(methacrylic acid) (PMA) or poly(acrylic acid) block, and, in some cases, a third PMMA... 

A further improvement of the multiphase reactor concept using lipase for enantioselective transformation has been recently reported, that is, an emulsion enzyme membrane reactor. Here, the organic/water interface within the pores at the enzyme level is achieved by stable oil-in-water emulsion, prepared by membrane emulsification. In this way, each pore forms a microreactor containing immobilized... 

Asterisks indicate that there were insufficient data to correlate results. Sets 1, 5, 9, 13 impeller midway in denser phase, H/4. Sets 2,6, 10,14 impeller midway in lighter phase, 3/7/4. Sets 3,7,11,15 impeller at organic-water interface, ///2. Sets 4, 8, 12, 16 two impellers, one midway in each phase, ///4, 3///4. (Reprinted with permission from Skelland, A.H.P., and Seksaria, R., Ind. Eng. Chem. Proc. Des. Dev. 17 (1), Copyright 1978, American Chemical Society.)... 

Polycrystalline thin films of CdSe have been prepared at the organic-water interface by reacting cadmium cupferronate in the toluene layer with dimethylselenourea in the aqueous layer.31 XRD measurements confirm the formation of cubic CdSe at the interface. TEM images reveal the films to be made up of nanocrystals with diameters ranging from 8 to 20 nm (Figure 10a). Time-dependent growth of the CdSe film at 20 °C has been examined by UV-vis absorption spectroscopy. All... 

When polar hydrocarbons or typical diphilic antifoams (fatty alcohols and acids, ether, siloxanes, etc.) are used, the stability of foam films decreases for two reasons. The first one is related to the adsorption displacement of the surfactant from the antifoam and the second one to the considerable change in the surfactant monolayer at the organic phase interface caused by the transformation of the foam film into an asymmetric film. The adsorption at the organic/water interface strongly decreases compared to the adsorption at the water/air interface. 

Prevention of the coalescence of the sticky, partially polymerized particles is a major problem in suspension polymerizations, and proper selection of stabilizing agents is important. Two kinds of additives are used to hinder coalescence of particles in suspension polymerizations. These are platelet-like mineral particles that concentrate at the organic-water interface, like Ca3(P04)2, and/or macromolecu-lar species that are soluble in water and insoluble in the particular organic phase. Poly(vinyl alcohol) and starch products are examples of the latter type. 

Transfer of Latexes from 0rganic-C02 to Organic-Water Interfaces... 

A polymer latex in CO2 with an organic-C02 interface may be transferred into water to form an aqueous latex with an organic-water interface. This... 

Scatena, L.R, and G.L. Richmond (2001). Orientation, hydrogen bonding, and penetration of water at the organic/water interface. J. Phys. Chem. B 105, 11240-11250. 

The sorption kinetics of the stabilizer molecules from the continuous phase to the organic-water interface changes with time. The time required for the sorption process to reach its steady-state is controlled by the transfer of the stabilizer molecules from the continuous phase to the droplet surface and their subsequent reconformation and rearrangement at the organic-water interface. As the stabilizer concentration increases, the time required for the system to reach equilibrium is reduced, indicating an increased polymer diffusion rate [21]. Nilsson et al. [22] argued that the stabilizer molecules diffuse very quickly to the liquid-liquid interface, but not in the more thermodynamically stable conformation and, thus, a rearrangement takes place until the system reaches its equilibrium. 

LIM ZHONG GiemicaBy Benign Synthesis at Organic—Water Interface 171... 

Palladium can be recovered quantitatively at the organic-water interface after the reaction, and it shows the same catalytic activity as the fresh catalyst under similar conditions. The reaction has an activation energy of 23.9 kcal/mol and a first-order dqiendence on the catalyst and substrate concentrations each, a zero-order dependence on the carbon monoxide partial pressure, and a variable-order dqiendence on the aqueous sodium hydroxide concentration. 

---