Modular Synthesis and Facile Network Formation in Catechol Functionalized Block Copolymers

Mussel foot proteins contain large amounts of catecholic amino acids, such as 3,4-dihydroxy-L-phenylalanine (DOPA), which impart remarkable adhesion and curing properties. Their cohesive strengths, crucial for preventing mechanical failure, originates from controlled oxidation of catechol into quinone and their subsequent catechol-quinone crosslinking. Inspired by this mechanism, numerous studies have investigated catechol oxidation as a strategy to form wet-curing hydrogels from synthetic and bio-derived polymers. However, current catechol-functionalized macromolecules suffer from slow curing (hours to days) and poor mechanical strengths due to poor control over the content and placement of catechol groups in polymer backbones. In this work, we overcome these limitations by synthesizing block polycatechols with high content and controlled placement of catechol groups. Tunable oxidation of the catechol groups into quinones resulted in rapid three-dimensional crosslinking and hydrogel formation within seconds. The resulting hydrogels achieve shear strengths up to 50 kPa – significantly exceeding those of existing bio-inspired hydrogels. Furthermore, by systematically modulating the oxidation state across a library of block polycatechols, we establish catechol oxidation as a powerful handle to control both gelation kinetics and mechanical strength. These findings provide fundamental insights into the role of oxidation-driven crosslinking in the material formation of both synthetic and natural adhesive systems.