Silica-type materials

In bulk coating processes, bulk materials are joined to the substrate either by a surface melt process or by attachment of the solid material. An example of the latter is the application of heat-resistant tiles of silica-type material to the aluminum alloy skin of a space shutde vehicle, enabling the vehicle to withstand the reentry heat. 

AS STRUCTURE-DIRECTING AGENTS FOR SILICA-TYPE MATERIALS 606... 

Novel Blocked Macromolecular Amphiphiles as Structure-Directing Agents for Silica-Type Materials... 

In the second part of this chapter recent progress towards nanostructured polycrystalline assemblies from block copolymer mesophases will be described. First, developments in the approaches presented so far toward nanostructured materials with crystalline nanoparticles embedded in an amorphous silica-type material will be discussed. The second section will describe a new assembly approach for the development of nanostructured materials with highly crystalline walls. The last part highlights achievements of the self-assembly of block copolymers with... 

The 1-pK model can be also applied to model surface charging of the silica-type materials (cf. Section B). For these materials the surface charging is due to the following reaction. 

Most solid column packings are clays or silica type materials, which means that their surfaces are aluminates or silicates and consist of large numbers of terminal -OH groups that are highly polar. Usually a nonpolar solvent such as hexane is used as the mobile phase. When moderately polar compounds are dissolved in the mobile phase and passed over the column packing, the more polar compounds are retained longer than the less polar compounds, and a separation results. 

For Si work the glass in the probe area can be a nuisance, since it gives a broad resonance ca. 110 ppm to low frequency of the signal due to Me Si. This is only really a difficulty when compounds containing silicon tetrahedrally bonded to four oxygens are being studied, since otherwise chemical shifts are sufficiently removed from the problem area. Use of plastic NMR tubes (and even plastic probe components) can reduce or eliminate the problem. Convolution-difference methods are also applicable in some cases, but not when the sample itself contains silica-type materials—in such cases a blank run must be employed (14), which reduces spectrometer efficiency substantially. 

---