A Novel and Versatile Grafting Procedure : Toward the Highest Possible Sulfonation Degree of Mesoporous Silica

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Timm, Jana ; Marschall, Roland:
A Novel and Versatile Grafting Procedure : Toward the Highest Possible Sulfonation Degree of Mesoporous Silica.
In: Advanced Sustainable Systems. Bd. 2 (2018) Heft 3 . - 1700170.
ISSN 2366-7486
DOI: https://doi.org/10.1002/adsu.201700170

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Abstract

Abstract A unique method for the postsynthetic functionalization of ordered mesoporous silica materials is described. The functionalization is done via a chemical vapor deposition?type method and leads to the quantitative reaction of isolated surface silanol groups of mesoporous silica materials with organosilane molecules. The result is a highly sulfonated material by anchorage of 3?mercaptopropyltrimethoxysilane molecules and subsequent oxidation of the thiol groups to sulfonic acid groups. Ordered mesoporous KIT?6 and SBA?15 are chosen as model systems. The sulfonated material exhibits a functionalization degree of 1.05 resp. 1.32 molecules nm?2, which is on the maximum of the theoretical achievable functionalization density resulting in high ion exchange capacities of 1.22 and 1.12 mmol g?1. The versatility and mildness of this method opens up functionalization possibilities for a wide range of other materials, which could be sulfonated or otherwise modified with silanes, and tailored for the further application in catalysis or as solid?state proton conductors.