A simplified approach to achieve gecko-mimic nano-structural adhesives by a simple polymer

In this work, we graft polyacrylate with 3,4-dihydroxyphenylalanine, a functionality alike adhesive protein in mussels, to obtain a mussel-mimic polyacrylate with good adhesive property and interesting nano-patterns during adhesion. The chemical structure of the product is confirmed by 1H NMR that dopamine is grafted onto the polymer. The analysis of the tensile strength test reveals that the adhesive is improved more than 2 times, from 53 to 124 KPa, when polyacrylate grafted by dopamine. The analysis of the static water contact angle suggests that the hydrophilic of the as-synthesized final polymer is enhanced. It is very interesting to observe that such an adhesive material can form nano-patterns on the adhesion interface during bonding, at about 100 nm in diameter each contact point, which something look like the gecko foot structure. This structural feature maybe related to the increasing adhesive properties of such materials.