Acid-based resorcinol-formaldehyde xerogels synthesized by microwave heating

Abstract

The polymerization reaction that takes place between resorcinol and formaldehyde is spontaneous but slow. For this reason, compounds are often used to increase the reaction rate and reduce the synthesis time. These compounds can be basic or acidic and their nature and concentration can be used to modify the mechanisms of the reaction and the final properties of the materials. In this work, the differences in the final properties of the organic xerogels obtained with basic or acid boosters have been studied. It was found that, irrespective of the nature of the booster, none of the end-product materials showed any differences in their chemical properties. Moreover, the concentrations of the components of the precursor solution (i.e., monomers, water, and methanol) were observed to have the same effect on the porous properties of the materials regardless of whether an acidic or a basic booster was used. However, differences in the porous properties were observed. It was found that the methanol content was crucial to tailor the porosity over the entire nanoscale when an acidic booster is used. These results are of great importance as acidic boosters allows to decrease synthesis time and, hence, to produce more competitive materials.