Boron gels, properties

Cubed compound, in PVC siding manufacture, 25 685 Cube lattice, 8 114t Cubic boron nitride, 1 8 4 654 grinding wheels, 1 21 hardness in various scales, l 3t physical properties of, 4 653t Cubic close-packed (CCP) structure, of spinel ferrites, 11 60 Cubic ferrites, 11 55-57 Cubic geometry, for metal coordination numbers, 7 574, 575t. See also Cubic structure Cubic symmetry Cubic silsesquioxanes (CSS), 13 539 Cubic structure, of ferroelectric crystals, 11 94-95, 96 Cubic symmetry, 8 114t Cubitron sol-gel abrasives, 1 7 Cucurbituril inclusion compounds,... 

Experiments with CPGs subjected to progressive thermal treatment leading to partial dehydroxylation of the surface and its enrichment in boron atoms showed specific adsorption properties of these materials differentiating them from silica gels [30,31,73]. It was found that depending on the type of adsorbate two trends in the adsorption behaviour of heated CPG can be observed [30,31]. The increase of thermal treatment time leads to the increase of CPG adsorption properties in relation to water, chloroform or hexane [30] (e.g. see Fig. 13). 

The adsorption of diethyl ether or tetrahydrofurane decreases for shortly heated glasses in comparison to non-heated ones and increases for longer heated CPG (e.g. see Fig. 14). This can be attributed to the described processes occuring on the CPG surface during its thermal treatment (dehydroxylation of Si-OH groups, creation of B-OH groups, increase of surface boron and sodium concentration, borate cluster formation). Each of these processes differently influences the adsorption properties of CPG. The adsorption properties of silica gel treated thermally in the same conditions (above 400°C) significantly decrease as the result of surface dehydroxylation. 

As indicated at the beginning, the presented discussion of CPG is selective. It focuses on the many properties distinguishing CPGs from silica gels. These differences are found in the porous structures of these materials and - mainly - in their surface properties. Both are built of Si02 and have surface covered with hydroxyl groups, but boron residue remaining... 

Pena-Alonso, R. Tamayo, A. Rubio, F. Rubio, J., Influence of Boron Concentration on the Surface Properties of TEOS-PDMS Hybrid Materials. J. Sol-Gel... 

James et al. synthesized a new gelator by combining a boronic acid moiety with the cholesterol skeleton (cholesterylphenylboronic acid 1). It was found that saccharide complexes of 1 efficiently gelatinize several organic solvents. The gelation properties such as the sol-gel phase transition... 

A remarkable property of the interpolymer complex gels based on boronate-diol interactions is their self-healing behavior. Because the polymers are crosslinked with reversible boronate ester bonds, the network can form again once it is broken. As Kiser et al. showed, the network structure can... 

S.K. Samanta et al. have reported the rheological properties of boron nitride nanotubes (BNNTs) filled gel nanocomposites which indicates that the flow properties of the resulting materials become resistant to applied stress upon incorporation of even a very low wt% of BNNTs. They have prepared gel nanocomposites using a gelator which is made up of all-trans tri-(p-phenylenevinylene) bis (aldoxime) (TPV, 1) which is capable of forming a physical gel in aromatic hydrocarbons such as toluene (Fig. 8a). A transparent solution of 1 (10 mg/mL)... 

---