Bioinspired adhesive polymer coatings for efficient and versatile corrosion resistance

The anticorrosion ability of ultrathin coatings with bio-inspired organic polymers is demonstrated. We prepared a series of catechol-containing poly(alkyl methacrylate)s by free radical polymerization. These copolymers were spin-coated on various corrosion susceptible metal/alloy substrates of magnesium, aluminum, copper and iron without any harsh pretreatment. Several key factors like molecular structure, composition ratio and processing conditions were wisely tailored to afford a transparent, firm and sub- micron polymer coating on those substrates. Corrosion resistance of the polymer-coated substrates was thoroughly investigated by immersion tests in salt-water and acidic solutions, polarization tests, and visual inspection. Formation of an anomalous dense layer of ca. 5 nm thickness adjacent to the metal surface and a remarkable effect of thermal treatment were clearly observed by neutron reflectivity measurements, leading to a highly protective ability against foreign molecules e.g. water or corrosive ions. A key molecular design for anticorrosive polymer coating was revealed to be a combination of strong and versatile binding ability of catechol units and defect free polymer layers formed on the metal substrates in the presence of hydrophobic alkyl chains.