Water activated catechol adhesive allows dip coated antimicrobial coatings

Bioadhesives comprising of catechol crosslinkers have displayed broad utility against both soft and hard substrates. However, catechol's two-part adhesion chemistry requires oxidative chemicals that are detrimental to organic substrates. Herein, a water-activated adhesive with inherent antibacterial properties is prepared by grafting catechol groups onto branched polyethylenimine (PEI-DBA₂₀). The resultant PEI-DBA₂₀ is stable in organic solvents but undergoes curing in the presence of water. The in-built oxidation method relies on the close proximity of catechol/Schiff base functional groups that form tautomers in the presence of aqueous solvents. The curing mechanism is demonstrated by dip coating hydrated substrates, where the grafted dendrimers subsequently crosslink and form thin films. Coated PET films and polyester textiles exhibit an antimicrobial surface with 4–6 log reduction against model Gram-negative bacteria.