Functionality of Organically Modified Silanes

The functionality of organically modified silanes influences the fabrication of the monolith in several ways. As already mentioned in Section (10.2.3.4), the size of the organic ligand can induce steric effects and slower reaction time. In addition, less polymerized silanol groups (due to the functional ligand groups) ako lead to slower reaction time. When the reaction time is slower, a monolith can be fabricated more easily. 

On the other hand, a polymerizable ligand allows formation of organic networks in addition to the inorganic one. Such an organic network can create cross-linking between the network walls and therefore reinforce the structure allowing easier conditions to fabricate monoliths. 

Functional group properties such as hydrophobicity or hydrophilicity allow control of the properties of the product monolith and tailored physical and mechanical properties. 

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In monolith febrication it is required to take into account the influence of the precursor gradient chemical composition on the sol-gel process. Parameters that affect the process are metal alkoxide precursor types, pH effect - type of catalyst used, H2O Si molar ratio (/ ), steric effect of precursor ligand groups, and functionality of organically modified silanes (ORMOSIL). 

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