(30a) Polyelectrolyte Complex Hydrogels: A Platform for Wet Adhesives and 3D Bioprinting Inks

Significant advances in emulating natural glues have led to a diversity of wet adhesive chemistries. However, most current adhesives cure slowly in unprotected aqueous environments, leading to precursor deactivation, dilution, and weak adhesion. In this talk, I will discuss our progress in developing robust wet adhesives based on polyelectrolyte complex-interpenetrating network (PEC-IPN) hydrogels. These hydrogels are fabricated by curing polymeric adhesive precursors in protected environments provided by self-assembled polyelectrolyte complex (PEC) hydrogels, thus mitigating precursor dilution. In the resulting PEC-IPN hydrogels, the PEC network also features a mesoscale hierarchical structure, contributing to the adhesives' superior mechanical and adhesive performance. Model PEC-IPN hydrogels comprising a PEC network composed of oppositely charged block polyelectrolytes and a covalently crosslinked tetra-PEG network will be demonstrated to serve as a material platform for robust and tough wet adhesives. X-ray scattering investigations will establish the persistence of the PEC network upon the inclusion of tetra- PEG chains in it and their subsequent photocrosslinking. Simultaneously, marked improvements in shear and tensile strengths of PEC-IPN hydrogels upon incorporating the covalent tetra-PEG network, even as a minor component, will be demonstrated. We will conclude by demonstrating proof-of-concept demonstrations of the utility of PEC-IPN hydrogels as bioadhesives and as inks for 3D bioprinting applications.