Synthesis and Hydrogelation of Bioinspired Block Copolymers

Marine organisms such as mussels and sandcastle worms secrete glue proteins that enables robust wet adhesion and curing properties. The adhesive attributes of these proteins have been ascribed to the presence of catecholic 3,4-dihydroxy-l-phenylalanine (DOPA) moieties. We draw inspiration from these marine adhesives to create block polymers with catechol functionalities to seek strong, tunable adhesion in wet environments. Here, we report the preparation of symmetric polyethylene glycol (PEG) block copolymers containing well-defined number and location of unprotected catechol groups. Tunable oxidation of the catechol end blocks into quinones and subsequent catechol-quinone crosslinking resulted in three-dimensional polymer network formation. Using dynamic oscillatory shear rheometry and small angle X-ray scattering we monitor and study the hydrogelation as a function of oxidation strength and time. This approach allows for investigating the effects of molar concentrations of adhesive groups, polymer molecular weight, and concentration and aid in enhancing the adhesive capabilities of PEG-based hydrogels.