The structure effect upon gallic acid re-binding in molecularly imprinted organosilica

This paper debates the effect of the stabilizer (vinyl benzyl trimethyl ammonium chloride-VBTAC or cetyl trimethyl ammonium chloride-CTAC) and the structure (typical SiO2 matrix or inorganic-organic interpenetrated matrix) influence in molecular imprinting of gallic acid-polyphenol class of templates. For this purpose, gallic acid-imprinted particles were obtained via typical polycondensation sol-gel reactions and via sol-gel/radical polymerization concurrent reactions of tetraethoxy silane (TEOS) and aminopropyl ethoxy silane (APTES) or vinyl triethoxy silane (VTES), respectively. The influence of the mesophase formation and stabilizer nature upon the re-binding of gallic acid was investigated using thermal, infrared and morphology measurements. Adsorption assays of organosilica particles were well correlated with their physical properties. Unlike the polycondensation of TEOS with APTES in the presence of CTAC, concurrent radical polymerization of VBTAC consumed the vinyl functionalities of VTES, decreasing the capacity of VBTAC to mediate the mesophase formation and the capacity of VTES to coordinate template molecules; hence, both the binding capacity and the memory effect of the interpenetrated organosilica structure were significantly affected. [GRAPHICS] .