Periodic synthesis with surfactants

Many of the non-silica compositions showed problems with the stability and quality of the structure. Efforts to address these issues have been on going and quite successful in some cases such as all-alumina compositions (see below). Silica-based materials remain dominant as the most versatile and best quality molecular sieves (structure and stability) available by a facile synthesis. These attributes, especially the convenient synthesis made mesoporous silicate attractive for post-synthesis functionalization with other elements as well as organic moieties with active groups/ccnters. Recently the compositional diversity has been extended further to include both silica and organic moieties within the framework. The new class is referred to as periodic mesoporous organosilicas (PMOs). The synthesis involves surfactant-assisted assembly by hydrolysis of organo-silicon compounds. Additional discussion of the PMOs is presented below. 

Assembly of zeolite seeds, protozeolite clusters, etc, into mesoporous frameworks -zeolite synthesis mixture is crystallized for a certain period of lime to generate zeolite fragments and then treated with surfactant to assemble the mesoporous structure [58]... 

Two surfactants, anionic (AOT) and non-ionic (Brij 30), were used in forming pairs of reverse microemulsions with the W/O system n-decane/aqueous solution (calcium nitrate hydrate or diammonium hydrogen phosphate) for the synthesis of long particles of calcium phosphate [333]. On mixing of the reverse microemulsions, precipitation took place within short periods. The particles had a Ca P ratio of about 1.50 and a size of 10 nm (diameter) and 50-60 nm (length). 

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