Pore size of gradient aerogels

Using NaOH as catalyzer, gradient aerogels were prepared via sol-gel polymerization with resorcinol and furfural. The sol-gel process and aerogel structure were investigated by optical microscopy, scanning electron microscope (SEM), transmission electron microscope (TEM) and surface area and pore size analyzer. The impacts of temperature, solvent, mass content of reactants on pore structure of gradient aerogel were discussed particularly. The results showed that sedimentation equilibrium make sol forming concentration gradient, and the aerogels will have gradient structure. Pore size gradient of aerogel has been changed from 0.01 nm to 8.9 nm by controlling parameters to change sedimentation time and velocity of colloid particles.