Synthesis of Super-hydrophilic Mesoporous Silica via a Sulfonation Route

The surface of mercapto-functionalized mesoporous silica having a highly ordered open pore network was modified into a super-hydrophilic surface through a stepwise sulfonation process involving oxidation and ionization reactions. The initial mesoporous silica was prepared using an acid-catalyzed sol-gel reaction between tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) in the presence of a triblock copolymer surfactant (P123). The synthesized silica retained its characteristic mesoporous and hexagonal structure even after the addition of 10 % of MPTMS, as determined through XRD and BET analyses. Thereafter, the immobilized mercaptopropyl groups in the open pore network were oxidized to sulfonic acid moieties by hydrogen peroxide, followed by ionization with sodium hydroxide to generate super-hydrophilic sodium sulfonate groups. The surface-modified mesoporous silica was characterized using FT-IR spectroscopy, TGA/DSC, acid-base titration, ICP-AES, contact angle measurement, and solid-state Siand C-MAS NMR spectroscopy at appropriate steps during the modification process.