Revisiting the adhesion mechanism of mussel-inspired chemistry

• Published in: Chemical science (Cambridge) Vol. 13; no. 6; pp. 1698 - 175
• Main Authors: Zhang, Chao, Xiang, Li, Zhang, Jiawen, Liu, Chang, Wang, Zuankai, Zeng, Hongbo, Xu, Zhi-Kang
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 09-02-2022; The Royal Society of Chemistry
• Subjects: Adhesion; Catechol; Chemistry; Functional materials; Oxidation; Polymerization
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d1sc05512g

Mussel-inspired chemistry has become an ideal platform to engineer a myriad of functional materials, but fully understanding the underlying adhesion mechanism is still missing. Particularly, one of the most pivotal questions is whether catechol still plays a dominant role in molecular-scale adhesion like that in mussel adhesive proteins. Herein, for the first time, we reveal an unexplored adhesion mechanism of mussel-inspired chemistry that is strongly dictated by 5,6-dihydroxyindole (DHI) moieties, amending the conventional viewpoint of catechol-dominated adhesion. We demonstrate that polydopamine (PDA) delivers an unprecedented adhesion of 71.62 mN m
−1
, which surpasses that of many mussel-inspired derivatives and is even 121-fold higher than that of polycatechol. Such a robust adhesion mainly stems from a high yield of DHI moieties through a delicate synergy of leading oxidation and subsidiary cyclization within self-polymerization, allowing for governing mussel-inspired adhesion by the substituent chemistry and self-polymerization manner. The adhesion mechanisms revealed in this work offer a useful paradigm for the exploitation of functional mussel-inspired materials.
A 5,6-dihydroxyindole (DHI)-dominated mechanism in the interfacial adhesion of mussel-inspired chemistry is first proposed and demonstrated by the fusion of
in situ
force measurements with molecular-scale simulations.