Solvating diluent

The porosity of polymer beads is controlled by the ratio of diluents (poro-gen) to monomers in the organic phase. The increase in the ratio of diluents to monomer in the monomer mixture increases the porosity of polymer beads. The pore size can be manipulated by adjusting the ratio of nonsolvating and solvating diluents in the monomer mixture. The increase in the ratio of nonsolvating diluent (precipitant) in the monomer mixture increases the pore sizes and vice versa. 

PPS-type resin Porous SDVB resin obtained by using a nonsolvating diluent along with a solvating diluent in the polymerizing mixture PM-type resin Porous SDVB resin obtained by incorporating a preformed linear polymer in the polymerizing mixture... 

M 17. — — andT.R. E. Kressman Solvent-modified polymer networks. I rt IV. Styrene-divinyibenzene copolymers made in the presence of non-solvating diluents. J. Chem. Soc. 1965, 304. 

Formation of macroporous copolymers in the presence of solvating diluents... 

Kolarz [347] synthesized macroporous copolymers in the presence of a mixture of polystyrene with xylene as the solvating diluent (Tables 3.5 and 3.6). As found, at a constant dilution, the increase of DVB concentration from 8 to 12% involves a noticeable increase in the porosity of the copolymers, while further increase of crosshnking density does not change anymore the parameters of the porous structure. The highest porosity was characteristic of samples prepared in the presence of approximately equal amounts of polystyrene and xylene. Similar to the copolymers prepared with polystyrene alone, it was observed that pore size... 

In general, the accessibility of functional sites is determined by the relationship between the dimensions of the pores and of solute molecules. The peculiar behavior of macroporous resins logically follows from the bimodal character of their pore size distribution. Space between the primary nodules and their aggregates presents transport channels with easily accessible functional groups on their walls. When the porous support was formed in the presence of a solvating diluent, such as toluene, its transport... 

The density of population and orientation of surfactants at the interface depends upon their structure and concentration and the type of diluent. The effect of the latter is decisive. Molecules of aromatic hydrocarbons that have n electrons compete with extractant molecules for access to the hypothetical interface, and solvating diluents disturb the adsorption of extractant molecules and the penetration of... 

When the solvent is a good solvater, the determination of the solvation number b is difficult, unless the dependence of the extractant concentration on the solvent can be obtained. Solvation numbers can be obtained in mixtures of a solvating extractant and an inert diluent like hexane. Further, in these systems the extraction of the metal commonly requires high concentrations of salt or acid in the aqneons phase, so the activity coefficients of the solutes must be taken into acconnt. 

Organic extractants facilitate the transfer of the metal ions from the aqueous phase to the organic phase in solvent extraction. Based on the nature of the organic extractant, the metal ion, and the diluent, effective separation methods can be devised. Uranium extraction into diethyl ether from nitrate medium by salting out is perhaps one of the first uses of solvent extraction for large-scale actinide processing (9). In this case, ether not only acts as the diluent, it also acts as the extractant, which works according to the solvation mechanism (discussed below). 

The organic extractants used for the separation of metal ions broadly fall into three classes, chelating extractants, solvating extractants, and ion-pair extractants. For the first two classes, usually nonpolar organic diluent is preferred. On the other hand, polar diluents are preferred in the case of ion-pair extraction. 

The term Third-Phase Formation in solvent extraction refers to a phenomenon in which the organic phase splits into two phases (126). One of the two phases is diluent rich, whereas the other is rich in extractant and also contains the metal solvate. Third-... 

Following the recommendation of Reinhoudt,23 in almost the majority of cases, nitrophenyl alkyl ethers were used as diluents for the extraction tests by the Cadarache group, because they are able to dissolve calixarenes at relatively high concentration. Moreover, the basicity as well the dielectric constant of these diluents improves cation extraction by better solvation of the associated nitrate anions (Table 4.3). 

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