Porosity of SBA-15 after functionalization of the surface with aminosilanes

• Detailed porosity characterization of SBA-15 silica before and after its surface functionalization with (RO)3SiNH molecules was reported.
• The necessity of using complementary methods to study properties of porous materials was demonstrated.
• The comparison of pore diameter and pore volume obtained from nitrogen sorption as well as thermoporosimetry and thermodesorption of n-nonane was provided.
• Water thermoporosimetry was found to be the most advisable for investigation such systems.

Functionalization of the mesoporous silica walls by organic species results in formation of porous hybrid materials. Combination of organic and inorganic components leads to the materials whose properties differ considerably from those of their individual, isolated components, especially with respect to their surface chemistry, hydrophilicity/hydrophobicity and/or pore connectivity and size distribution. In this paper a detailed porosity characterization of SBA-15 silica before and after its surface functionalization with (R2O)3-Si-R1-NH2 molecules is reported. The results obtained from nitrogen sorption were compared to those derived from quasi-equilibrated thermodesorption of n-nonane and from water and n-heptane thermoporosimetry. A small decrease of the pores size and pore volume upon the modification was detected for all amine functionalities, the largest in the case of N-(2-aminoethyl)-3-(trimethoxysilyl) propylamine. Water thermoporosimetry was found to be the most sensitive method, allowing to quantify these differences.

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