Understanding the Kinetic Aspects Responsible for the Formation of 3‐Aminophenol‐Formaldehyde Resin Beads with Different Morphologies

This work investigates the kinetics and mechanistic details involved in the synthesis of phenolic resin beads when formaldehyde is added in one‐shot or dropwise to react with an excess amount of 3‐aminophenol. In one‐shot synthesis, the sharp rise in formaldehyde concentration, [F], to a high level leads to a rapid kinetics that triggers simultaneous substitution, condensation, and polymerization reactions for the formation of homogeneous, fully‐cross‐linked beads that cannot be etched by acetone. Conversely, dropwise synthesis, characterized by a significantly lower [F] in the early stage, results in the formation of low‐substitution monomers, which then polymerize into heterogeneous beads consisting of a cross‐linked shell and an etchable core. With dropwise addition, it can precisely control the level of [F] in the reaction mixture to obtain resin beads with tunable diameters. After etching away the lightly‐crosslinked core, the beads can be carbonized to obtain hollow carbon beads sought for applications in catalysis and energy storage.