Phase-directing agent

An alternative method to synthesize organically functionalized mesoporous silica phases is the co-condensation method (also called one-pot synthesis or direct synthesis). Historically, the classical co-condensation reaction involved tetraalkoxysilane [(RO Si (predominantly TEOS or TMOS)] and a terminal organotrialkoxysilane of the type (R 0)3Si-R in the presence of structure-directing agents (Fig. 3.9, top). Meanwhile, not only bis- and multi-silylated precursors are used, that is, precursors of the type [(R 0)3Si]mR, m > 2 (Fig. 3.9, bottom), together with TMOS/TEOS, but... 

Novel methods of preparation of vanadium phosphate catalysts have been explored by several groups these methods include hydrothermal synthesis, gas-phase s)mthesis, supercritical antisolvent precipitation, and the use of templates and structure-directing agents to modify the bulk... 

The interstices between the epithelial cell layers communicate directly by an aqueous pathway with the stroma and aqueous humor. Lipophilic drugs can readily enter the epithelium, because its barrier is composed of phospholipid membranes. Because the epithelium contains more than two-thirds of the plasma membrane mass of the cornea, it is the most significant storage depot for agents that readily partition into lipid media. The release rate of drugs from the epithelium depends on their tendency to reenter an aqueous phase.Thus, agents that are very lipophilic have a very long half-life once in the epithelium. 

Amphiphilic inorganic-organic block copolymers (PDMS-h-PEO) with variable block lengths were successfully syndiesized. The obtained polymers revealed predominantly lamellar phases in their aqueous solutions. At low concentrations the spcmtaneous fisrmation of vesicles was obsaved. The polymers can be applied as structure-directing agents in the synthesis of mesostmctured silica-based thin films. 

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