Acrylate monomer polymerization triggered by iron oxide magnetic nanoparticles and catechol containing microgels

Phenol and its derivatives are the most used polymerization inhibitors for vinyl-based monomers. Here, we reported a novel catalytic system composed of mussel inspired adhesive moiety, catechol, in combination with iron oxide nanoparticles (IONPs) to generate hydroxyl radical ((OH)-O-center dot) at pH 7.4. Catechol-containing microgel (DHM) was prepared by copolymerizing dopamine methacrylamide (DMA) and N-hydroxyethyl acrylamide (HEAA), which generated superoxide (O-center dot(2)) and hydrogen peroxide (H2O2) as a result of catechol oxidation. In the presence of IONPs, the generated reactive oxygen species were further converted to (OH)-O-center dot, which initiated free radical polymerization of various water-soluble acrylate-based monomers including neutral (acrylamide, methyl acrylamide, etc.), anionic (2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt), cationic ([2-(methacryloyloxy) ethyl]trimethylammonium chloride), and zwitterionic (2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide) monomers. Compared with the typical free radical initiating systems, the reported system does not require the addition of extra initiators for polymerization. During the process of polymerization, a bilayer hydrogel was formed in situ and exhibited the ability to bend during the process of swelling. The incorporation of IONPs significantly enhanced magnetic property of the hydrogel and the combination of DHM and IONPs also improved the mechanical properties of these hydrogels.

Automated summary

In this study, a novel catalytic system composed of mussel inspired adhesive moiety, catechol, and iron oxide nanoparticles (IONPs) was developed to generate hydroxyl radical at pH 7.4 for free radical polymerization of various water-soluble acrylate-based monomers. The system does not require additional initiators and the formed bilayer hydrogel exhibits magnetic and improved mechanical properties.