Enhanced Adhesion of Mussel-inspired Adhesive through Manipulating Contents of Dopamine Methacrylamide and Molecular Weight of Polymer

The aim of this study is to investigate the effect of the contents of modified 3, 4-dihydroxyphenyl-L-alanine (DOPA), named as dopamine methacrylamide (DMA), on the adhesion of mussel-inspired adhesives in air and water. A series of adhesives, p(DMA-co-MEA), were synthesized by copolymerized DMA and methoxy ethylacrylate (MEA) with the content of DMA from 2 mol.% to 10 mol.%. Results of 1 H NMR show that the contents of DMA in all adhesives are near to the theory ratios of DMA in the staring reagents. Adhesives with more than 5 mol.% of DMA appear adhesion, while adhesives with 2 mol. % and 3 mol. % of DMA show almost no adhesion in air and water. Adhesive with 7 mol.% of DMA has the highest molecular weight and adhesion either in air or in water in all adhesives. Adhesion of adhesive is synergistically influenced by the content of DMA, molecular weight and elastic modulus of adhesive. It is because that higher content of DMA would provide more DOPA, which leads to the coordination bond between DOPA and metal ions. It is feasible to develop the mussel-inspired adhesive through incorporating DMA into polymers, which will have potential application in the clinic.