Carboxylic acid-functionalized porous silica particles by a co-condensation approach

Andrea Feinle,Nicola Hüsing,Franz Leichtfried,Sonja Straßer

doi:10.1007/s10971-016-4090-4

Andrea Feinle, Nicola Hüsing + Show 2 more

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https://doi.org/10.1007/s10971-016-4090-4

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Abstract

Novel stable carboxylic acid derivatized alkoxy silanes are co-condensed with tetraethyl orthosilicate in the presence of a structure-directing agent in a direct “one-pot” synthesis to porous carboxy-modified silica particles. Special emphasis is given to the influence of an increasing amount of 5-(triethoxysilyl)pentanoic acid and sodium hydroxide on the morphology and porous structure of the co-condensation products. The simultaneous conversion of both silanes resulted in the formation of mesoporous, monodisperse spherical particles with diameters between 100 and 140 nm and specific surface areas up to 900 m2 g−1. Additionally, adsorption equilibrium studies were performed, in which the particles modified with carboxylic acid groups showed an increased adsorption rate toward methylene blue compared to pure silica materials.Graphical

Highlights

Hybrid mesoporous particles carrying functional organic groups have significantly broaden the application spectrum of pure silica materials, e.g., they can be used as adsorbents [1] or as active sites for biomolecule anchoring and polypeptide synthesis [2, 3]
Adsorption equilibrium studies were performed, in which the particles modified with carboxylic acid groups showed an increased adsorption rate toward methylene blue compared to pure silica materials
Carboxylic acid-derivatized silica materials are mostly prepared by post-synthetic strategies comprising several steps, such as (1) hydrolysis of cyanides to carboxylic acid groups by adding concentrated sulfuric acid to the cyanidemodified silica particles [14,15,16,17], (2) hydrolysis of anhydride groups resulting in a material with a high density of carboxylic acid groups [18,19,20], or (3) hydrolysis of ester compounds [21]

Summary

Introduction

Hybrid mesoporous particles carrying functional organic groups have significantly broaden the application spectrum of pure silica materials, e.g., they can be used as adsorbents [1] or as active sites for biomolecule anchoring and polypeptide synthesis [2, 3]. Organofunctionalized silica materials are typically prepared via co-condensation reactions of two or more different silanes. Via this method, many different reactive groups can be introduced into the material [4,5,6,7,8,9,10,11,12,13]. Carboxylic acid-derivatized silica materials are mostly prepared by post-synthetic strategies comprising several steps, such as (1) hydrolysis of cyanides to carboxylic acid groups by adding concentrated sulfuric acid to the cyanidemodified silica particles [14,15,16,17], (2) hydrolysis of anhydride groups resulting in a material with a high density of carboxylic acid groups [18,19,20], or (3) hydrolysis of ester compounds [21]. Possible applications and prospects of carboxylic group-functionalized ordered mesoporous silica materials are given in an excellent paper written by Han et al [22]

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