For example there are carbon foams and carbon aerogels, what is the difference when the author mentions "foam" or "Aerogel". Both are porous solids with large surface area. Please help
A distinction could be made in terms of pore size and shape. A foam is understood as a porous solid with micropores, while an aerogel as a solid with nanopores (below 100nm). The shape of the porous solid in a foam tends to resemble a wall-like network (such as a honeycomb). On the other side, the porous solid in the aerogels often forms a fiber-like interconnected network.
Foams are generally made using a foaming agent within a solution, forcing the structure to be formed around the gas which become the pores. Aerogels are self assembled structures that create a three dimensional architecture as the chain bonding occurs within the liquid medium. This creates a gel that spans the volume of its container, the liquid that is occupying the void spaces is then removed leaving the aerogel structure. Aerogel pore size is on the nanoscale ranging from micropores (< 2nm), mesopores (2-50nm), and macropores (>50nm)
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