Biomass polymeric microspheres containing aldehyde groups: Immobilizing and controlled-releasing amino acids as green metal corrosion inhibitor

This article reports a novel type of aldehyde-containing microspheres (ACMs) prepared by suspension polymerization using two biomass monomers, syringaldehyde methacrylate (SMA) and eugenol methacrylate (EMA), in which SMA provides aldehyde groups and EMA provides crosslinking structure. The ACMs with spherical morphology and adjustable pore sizes were observed by SEM images. Taking advantage of the reactive aldehyde groups, the ACMs can be used as a carrier for amino acids by forming Schiff-base, thereby leading to a novel type of metal corrosion inhibitor. The novel corrosion inhibitors demonstrate noticeable anticorrosion effects via controlled releasing amino acids. The releasing rate and amount can be tuned by varying pH and temperature. The ACMs can immobilize diverse amino acids (glycine, alanine, leucine), which all perform anticorrosion effects for the examined metals (aluminum, iron, zinc). The ACMs can be reused for at least ten times with little change in immobilizing and releasing amino acids. The present study establishes a facile, powerful strategy for immobilizing amino acids and even other compounds containing amino and hydrazine groups; it also provides a novel class of green corrosion inhibitors for metals with promising practical applications.