Synthesis of Super-hydrophilic Mesoporous Silica via a Sulfonation Route

Abstract

Abstract: The surface of mercapto-functionalized mesoporous silica having a highly ordered open pore net-work was modified into a super-hydrophilic surface through a stepwise sulfonation process involving oxida-tion and ionization reactions. The initial mesoporous silica was prepared using an acid-catalyzed sol-gel re-action between tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) in the presence of a triblock copolymer surfactant (P123). The synthesized silica retained its characteristic mesoporous and hex-agonal 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 spectro-scopy, TGA/DSC, acid-base titration, ICP-AES, contact angle measurement, and solid-state 29Si- and 13C-MAS NMR spectroscopy at appropriate steps during the modification process.