Stability of silane modifiers on alumina nanoporous membranes

Stability of silanes covalently bound to the surface of nanoporous alumina membranes was investigated and the reasons for variation have been identified as due to activation of Al–O–Si bond caused by local increase of pH from primary and secondary amines of the linker molecules. Transformation of amines into amides or passivation of alumina surface by as little as five atomic layers of deposited silica before silanization dramatically improve stability of immobilized molecules.