Anion-Exchange Material with pH-Switchable Surface Charge Prepared by Sol−Gel Processing of an Organofunctional Silicon Alkoxide

Abstract

A novel organofunctional silica material has been prepared by sol-gel technology. The material incorporates an organic substituent, propyl-N,N,N-trimethylammonium, which is linked to the silica matrix covalently. This material is anion exchangeable and exhibits an improved selectivity toward chloride over more lipophilic anions. It is optically transparent and has been characterized by thermogravimetric analysis, infrared spectroscopy, nitrogen sorption analysis, capillary electrophoresis, cyclic voltammetry, and measurement of membrane potential. The material is porous, and almost all the covalently linked organic substituents are active in the pore space. The surface charge of this material is switchable in sign and its magnitude is dependent on pH and type of buffer. The potential of this material as a charged surface coating for capillary electrophoresis or an anion-exchange film for potentiometric sensors has been explored.

A modified supported bilayer/diblock polymer – Working towards a tunable coating for capillary electrophoresis

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Anisotropic self-organization of hybrid silica based xerogels containing bridged positively charged 1,4-diazoniabicycle[2.2.2]octane chloride group

“…Recently it was reported the synthesis of hybrids containing charged organic groups like quaternary ammonium, pyridinium and dabconium halides, bonded in a pendant way, which showed interesting properties like thermal stability, water solubility, ability to form films over inorganic surfaces [27][28][29][30][31]. Due to these characteristics they can be used as anion-exchangers, stationary phase for chromatography and electrochemical devices [31][32][33][34][35].…”

Al2O3-coated 3-N-propylpyridinium chloride silsesquioxane polymer film: preparation and electrochemical property study of adsorbed cobalt tetrasulfophthalocyanine

“…The use of surface-modified porous solids as substrates for modification with thin layers of films having organofunctional groups such as ion exchangers, basic donor atoms, long-chain hydrocarbons, and metal oxides, prepared by grafting or sol-gel processing methods, has found numerous applications in adsorption [1], separation processes [2][3][4] and immobilization of electroactive species [5] and as catalysts [6] and sensors [7][8][9][10][11].…”