InterPore2026

Pore-scale transport effects of surface functionalization in silica aerogels

20 May 2026, 10:05

1h 30m

Poster Presentation (MS09) Pore-Scale Physics and Modeling Poster

Speaker

Mrs Yasemin Ozliman Farimaz (Ege University, Izmir Bakircay University)

Description

Aerogels are porous materials that have been the subject of extensive research for many years. Monolithic silica aerogels, due to their continuous pore network structure and lack of inparticles voids, are model systems used to study transport phenomena at the pore scale. In monolith aerogels prepared by drying under ambient pressure, crack formation is a more common problem than with other drying methods. Therefore, the effects of surface functionalisation on the pore connectivity and transport pathways are directly evaluated using indirect indicators. For monolithic aerogels dried at ambient pressure, quantitative analysis of these effects is limited.
In this study, monolithic silica aerogels were synthesized using tetraethyl orthosilicate (TEOS) via a two-step acid-base sol-gel process. Following this, hexamethyldisilazane (HMDS) surface silylation was applied to the aerogels to prevent shrinkage and cracking. After production, the surface chemistry was altered by post-grafting with controlled amounts of aminosilane, resulting in a series of samples with the same production history and geometry but at different functionalization levels. This strategy allows for the investigation of only the effect of surface functionalization, excluding structural differences that might occur during gel formation.
Characterization studies were conducted to determine the cross-scale structure-function relationships of the synthesized aerogels. The three-dimensional pore architecture was quantified by X-ray microcomputed tomography, allowing the extraction of transport-related metrics such as porosity, pore connectivity, and crumpleness. Surface area and porosity analyzer (BET) analysis was performed to obtain information about surface area and pore size distribution. Nanometre-scale structural features were investigated using scanning electron microscopy (SEM). Surface chemistry and functionalization efficiency were validated by Fourier-transform infrared spectroscopy (FTIR) spectroscopy and thermogravimetric analysis (TGA).
The results reveal that surface functionalization alters the transport regime by disrupting pore connectivity beyond a certain threshold. Although moderate amine binding largely preserves the pore accessibility, it was observed that tortuosity increases and effective pore accessibility decreases at higher functionalisation levels. This nonlinear behaviour demonstrates that surface modification can limit transport without a significant change in total porosity. This study aims not to develop a new material or adsorbent but rather to position monolithic silica aerogels as reference porous media to elucidate the effects of surface functionalization on transport at the pore scale. The findings highlight the importance of the balance between chemical properties and pore accessibility in the design of functional porous materials.
Keywords: silica aerogels, surface functionalization, pore-scale transport.