Phase contact structures silica particles

Thus, to decrease the free energy of MIX contact between water and hydrophobic silica should be minimal. A high viscosity of the MIX system and absence of bulk water prevent floating of MS particles that can occur at small amounts of both oxides in a diluted suspension. Therefore, primary particles of A-300 and their aggregates form dense shells (micelles) around MS particles with entrapped air that create a barrier preventing contact of water with MS and the formation of separated MS phase. The LT H NMR and NMR cryoporometry methods give useful structural information on the hydrophilic/hydrophobic silica-water mixtures and can be used to characterize the properties of dry water materials. 

Structural changes of fumed oxides occurring on HTT in the steam phase may be caused by such reasons (dependent, of course, on HTT conditions) as (i) mass transferring from smaller primary partieles to larger ones and merger of these particles due to coverage of their contacts by new silica... 

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