Surface functionalized ionosilicas

Scheme 16.4 Different types of surface-functionalized ionosilicas.

Surface-functionalized ionosilicas are generally synthesized either via postsynthesis grafting or hydrolysis-cocondensation reactions involving trialkoxysily-lated ionic precursors. Scheme 16.5 illustrates the two different synthetic methods involving a monosilylated imidazolium precursor 3-methyl-l-(3-(trie-thoxysilyl)propyl)-imidazolium chloride. 

Conventional cocondensation reactions involving ionic precursors in the presence of cationic or nonionic surfactant led to the formation of surface-functionalized ionosilicas featuring typical MCM-41 and SBA-15 architectures [98]. Similar to classical reaction involving organic trialkoxysilylated precursors, the use of ionic liquid precursors has shown to disturb the self-assembly of the... 

A second method for the formation of nanostructured surfiice-functionalized ionosilicas consists in the cocondensation reaction involving ionic precursor displaying surfactant-like behavior (Scheme 16.8) [108]. Template-directed syntheses of long chain-substituted silylated imidazolium or ammoniiun precursors in the presence of cationic surfactant such as CTAB or cetylpyridinium chloride yield highly structured ionosilica materials with surface-tethered ionic groups. 

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