A Brief Evaluation of Pore Structure Determination for Bioaerogels

Abstract

This review discusses the most commonly employed methods for determining pore size and pore size distribution in bioaerogels. Aerogels are materials with high porosity and large surface areas. Most of their pores are in the range of mesopores, between 2 and 50 nm. They often have smaller or larger pores, which presents a significant challenge in determining the exact mean pore size and pore size distribution in such materials. The precision and actual value of the pore size are of considerable importance since pore size and pore size distribution are among the main properties of aerogels and are often directly connected with the final application of those materials. However, many recently published papers discuss or present pore size as one of the essential achievements despite the misinterpretation or the wrong assignments of pore size determination. This review will help future research and publications evaluate the pore size of aerogels more precisely and discuss it correctly. The study covers methods such as gas adsorption, from which BJH and DFT models are often used, SEM, mercury porosimetry, and thermoporometry. The methods are described, and the results obtained are discussed. The following paper shows that there is still no precise method for determining pore size distribution or mean pore size in aerogels until now. Knowing that, it is expected that this field will evolve in the future.

Impact of Crosslinking on the Characteristics of Pectin Monolith Cryogels

“…Mercury porosimetry is a generally used method to characterize the texture of materials with large macropores. The pressure of mercury causes the contraction of biobased cryogels, which can cause the destruction of pores, so valuable information can be obtained sometimes only at smaller applied pressures [ 25 ]. However, during the measurement, not only the compression of samples occurs but also the partial crushing of cryogels, so the pore size distribution can not be determined by this technique.…”

Novel Core/Shell Nylon 6,6/La-TMA MOF Electrospun Nanocomposite Membrane and CO2 Capture Assessments of the Membrane and Pure La-TMA MOF

“…According to the IUPAC classification, a type IV isotherm was obtained for the Nylon 6,6/La-TMA MOF nanocomposite, and the adsorption/desorption isotherm exhibited an H3 hysteresis loop (Figure ). Thus, mesopores exist in this nanocomposite, and thus, Nylon 6,6/La-TMA MOF is classified as a mesoporous material. , The surface area of the composite was determined through the nitrogen uptake and applying BET calculations. BET, Longmuir, BJH, t plots, and other data were computed through different approaches (Table ).…”

Biological Thermal Performance of Organic and Inorganic Aerogels as Patches for Photothermal Therapy

“…In fact, the A BET observed was even slightly higher, and the pore diameter slightly smaller than what was previously published by others [ 21 ]. The volume and diameter of the pores herein reported were assessed by BJH approach, an analytical method widely used yet presenting some limitations that require a certain caution in the analysis of the results [ 41 ]. BJH-method typically underestimates the actual pore diameter from the aerogel samples, as it only considers pores within the range of 1.7–300 nm and neglects macropores visible in SEM analysis [ 20 , 41 ].…”

“…The volume and diameter of the pores herein reported were assessed by BJH approach, an analytical method widely used yet presenting some limitations that require a certain caution in the analysis of the results [ 41 ]. BJH-method typically underestimates the actual pore diameter from the aerogel samples, as it only considers pores within the range of 1.7–300 nm and neglects macropores visible in SEM analysis [ 20 , 41 ]. Accordingly, dp ,BJH values may be smaller than the actual mean pore size values for these aerogels.…”