Mussel-mimetic, bioadhesive polymers from plant-derived materials

Mussel-mimetic, bioadhesive polymers are synthesized from plant-derived sources. The strong adhesive action is caused by interactions between the catechol groups at the end of the polymer terminal chains and the substrate surface. Here, we present a preliminary study of the adhesion properties and a discussion of the adhesion mechanism.

Two bioadhesive polymers were synthesized from natural plant-derived monomers by the transesterification of: (a) caffeic acid (3,4-dihydroxycinnamic acid; DHCA) and p-coumaric acid (4-hydroxycinnamic acid; 4HCA) to produce poly(DHCA-co-4HCA); and (b) 4-dihydroxyhydrocinnamic acid (DHHCA) and 3-(3-hydroxyphenyl) propionic acid (3HPPA) to produce poly(DHHCA-co-3HPPA). Thermoplastic poly(DHCA-co-4HCA) or poly(DHHCA-co-3HPPA) was placed between glass, carbon, steel, or bovine dentin substrates, and a lap shear adhesion test was conducted to compare them using conventional cyanoacrylate glue and epoxy resin.

The greatest adhesion for all tested substrates was exhibited by poly(DHHCA-co-3HPPA), followed by epoxy resin adhesive, poly(DHCA-co-4HCA), and cyanoacrylate adhesive. The adhesive strength of poly(DHHCA-co-3HPPA) was greater than 25.6 MPa for glass, 29.6 MPa for carbon, 15.7 MPa for steel, and 16.3 MPA for bovine dentin.

The adhesion of poly(DHHCA-co-3HPPA) might be the strongest reported for a mussel-mimic adhesive system, and could be a feasible alternative to petroleum adhesives.