How smaller pores atop larger pores affect a material’s ability to dry and drain
DOI: 10.1063/10.0042698
How smaller pores atop larger pores affect a material’s ability to dry and drain lead image
Picture a sponge saturated with a fluid. You squeeze it, and the fluid is flushed out. But a sponge with a coating along its pores creates a network of micropores that retains the fluid, and any interactions with the sponge would be completely altered.
Porous materials are used in a wide range of real-world applications, from carbon capture to soil drainage to filtration. Any coating on such a material changes its surface — often intentionally, to increase the available surface area for a chemical reaction, or to add a layer of filtration — but this process also creates additional micropores.
Hamed Haddadi and David Heine modeled how the structure of a material with smaller micropores embedded within larger ones affects how the material dries and drains. Using a pore network — an abstraction of the complex geometry of interconnected pores atop pores — the researchers simplified the system into a set of balls, spheres, and sticks, allowing them to more easily study how a liquid flows through.
“We wanted to see which pore hierarchy is the primary reservoir of the fluid, because it guides our understanding of chemical reactions,” said Haddadi.
They found the smaller pores act as a reservoir, changing the way liquid generally spreads through a porous material. Therefore, the micropores created by coating processes can lead to drastic changes in the material’s functionality that must be considered.
“We need to strike a balance between the strength of the overall material and the available surface area, so we can’t just do a completely fine pore structure throughout,” said Heine. “We need to have a mixture of coarse pore structure to give it sufficient strength and fine pore structure to provide the necessary surface area.”
Source: “Pore-scale simulation of liquid retention in stratified porous microstructures,” by Hamed Haddadi and David R. Heine, Physics of Fluids (2026). The article can be accessed at https://doi.org/10.1063/5.0311550 .
