Encapsulated solvents

The current focus on highly porous materials has led to a great deal of activity in this field. Kitagawa and coworkers developed what they called porous coordination polymers that were rigid enough to survive loss of the encapsulated solvent from... 

The strategy of hybrid and gel electrolytes is very promising for lithium-ion batteries, but it seems less viable for lithium-metal batteries due to the reactivity of lithium metal with the encapsulated solvent. In fact, high conductivity is not the only parameter in selecting a successful polymer electrolyte for the development of lithium batteries a low interface resistance and a high interface stability over time are also required to assure good cyclability and long life. 

Polymeric entrapment/ encapsulation Solvent evaporation 8.20 Insulin PLGA 96-h systemic glucose level suppression, compared with 4h for uncoated insulin 6... 

The volume of the aggregates is approximated by the volume occupied by the surfactants and solutes in the aggregates but does not include encapsulated solvent. Then the aqueous volume is just the total volume of the lattice minus the aggregate volumes. We do not consider the solubilization phenomena here in detail some preliminary information on this is given by Talsania [26]. 

Encapsulated solvent residues result in surface disturbances if insufficiently dried during CM. 

Microencapsulation is a method for separating an activating solvent or a reactive catalyst from the adhesive base. The materials, whether solid or liquid, are packaged in very small microscopic capsules. When adhesion is desired, the encapsulated solvent is released by breaking the capsules by heat or pressure, and a tacky adhesive with instant grab is produced. In addition to solvents, small quantities of plasticizers or tackifiers may be... 

Most observed vesicles on the surface are flattened because the evaporation of the encapsulated solvents causes the ball to collapse. When vesicles are very stable, they may retain their three-dimensional shape on the snrface, which can be observed by Kim et al. have reported... 

Figure 3 Homodimerization of urea-based tris(2-ureidobenzyl)amine, forming a capsule that is very small to accommodate guests. The larger capsule derived by tris(3-ureidobenzyl)amine showed the presence of one encapsulated solvent molecule.

In addition to the preceding main-chain polymers, Rebek and coworkers have described the assembly of ditopic caUxarene units into polymeric capsules, polycaps, in chloroform, as a result of homo- and heterodimerization of urea and sulfonyl-urea groups on the upper rim of the calixarenes [73-75]. Each calixarene dimer along the polymer chain encapsulates solvent or other small molecule guests (e.g., 4-fluorodibenzene and o-dichlorobenzene). A schematic representation of a calixarene dimer and homopolymer is shown in Figure 20. ... 

Another approach is the use of encapsulated solvents included in soluble conductive polymers. Capsules will break upon damage, dissolve the matrix and restore the electrical contact between phases once the solvent has evaporated (Odom et al., 2012) as can be observed by the electrical conductivity test in Fig. 9.6e in which a drop of potential is detected when the system is damaged and restored after a period of time when a self-healing system is employed. The restoration of electrical (and thermal) conductivities is expected to significantly grow in the near future due to the broad application in many different fields. 

Figure 31.1 shows the structures of some of the calixarene and calixpyrrole derivatives that were found to self-assemble into dimeric capsules (see structures 2-5). The tetraureacalix[4]arenes (2) were found to from dimeric capsules with internal volumes estimated to be in the range of 160-200 [lib]. These dimeric capsules were found to encapsulate solvent molecules like chloroform and benzene and small ammonium salts [11]. In addition, it was demonstrated with the aid of diffusion NMR [16] that such dimers have a high affinity for charged systems, and it was found that tropylium cation and cobaltocenium cation have higher affinities than benzene and ferrocene, respectively, for the cavity of the dimer of 2 [17]. These and other studies demonstrated that indeed diffusion NMR is an excellent means to probe encapsulation [17, 18], a fact that was instrumental in the study of the large hexameric capsules of resorcin[4]arenes and pyrogallol[4]arenes as will be demonstrated below [18-20]. 

It was also shown that slow evaporation of organic solution of 7c allow to selectively remove the non-encapsulated solvent molecules leaving powders of stable hexameric capsules that contain solvent molecules these were studied by magic angle spinning solid-state NMR (MAS ssNMR) [45c]. The use of different H and [13]C MAS ssNMR experiments as well as 2D hetero-nuclear... 

Hybrid boron ester-Schiff-base hemicar-cerand eapsules 23-28 have been prepared in [29] by imine condensation of 3-aminophenylboronic acid with the corresponding carbonyl-containing ligand syntones by Scheme 2.12 these covalent capsules encapsulate solvent benzene molecules, thus giving the host-guest 1 2 cage complexes. 

Bis-cavitand capsules 257, 259, and 260 have been prepared [184, 185] in high-dilution conditions by Scheme 2.162. They encapsulate solvent guests as well as alkali metal cations and then-salts to give the corresponding cage complexes. 

A bis-hemicarcerand caging ligand 277 is reported by D. Rudkevich and coworkers in [198] to encapsulate solvent molecules and gases shown in Scheme 2.173 in solid state. 

The encapsulated solvent molecules shown in Scheme 3.91 are described in [87] to exchange their positions slowly on the NMR time scale within the cavity of the hydrogen-bonded capsule... 

A similar ligand syntone 375 has been self-assembled in [163] with silver(I) cations to give a AgsLs coordination capsule 728 by Scheme 4.160. It has a trigonal bipyramidal polyhedron with two ligand syntones as an enantiomeric pair this capsule encapsulates solvent acetonitrile molecules [163]. 

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