Enlarged pore size in nanoparticulated bimodal porous silicas: Improving accessibility

• The intra-particle mesopores in nanoparticulated bimodal porous silicas have been enlarged up to ca. 56%.
• We have established the limits for the mesopore expansion on the basis of classical principles of colloid chemistry.
• The resulting open architecture leads to an enhanced accessibility for guest species.

Mass-transfer kinetics seems to be highly favored in siliceous materials constructed from the aggregation of mesoporous nanoparticles. Besides intra-particle mesopores, over the course of the aggregation process an inter-particle (textural) large pore system is generated. Diffusion constrains through the resulting hierarchically structured pore systems mainly depend on the characteristics of the intra-particle mesopores. By using alkanes as swelling agents, we have been able to significantly increase the intra-particle mesopore size in previously well characterized UVM-7 materials. The Winsor-III-like behavior associated with the presence of alkanes in the hydro-alcoholic reaction media used in the surfactant-assisted preparative procedure allows explaining the existence of limits to the mesopore size expansion. A preliminary study on enzyme adsorption by these UVM-7-modified solids offers promising results about their capabilities as supports for processing a variety of biomolecules.

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