(122g) Hybrid Hydrogels Comprising Interpenetrating Electrostatic and Covalent Networks

Polyelectrolyte complex (PEC) hydrogels form upon spontaneous association and self-assembly of oppositely charged block polyelectrolytes in aqueous media. Their swift electrostatic self-assembly, responsiveness to changes in ionic strength of their surroundings, and self-healing attributes have led to promising avenues for their use in diverse applications ranging from drug delivery to wet adhesion to 3-D bioprinting. However, their application-specific development requires a precise tuning of their microstructure and bulk properties, as well as strategies to overcome the interdependence between their microstructures and shear response and improve their poor tensile strength.

In this presentation, we will demonstrate a materials design platform for fabricating hybrid hydrogels comprising interpenetrating PEC and covalent networks. Mesoscale structure and bulk properties of a model hybrid hydrogel system comprising oppositely charged ABA triblock polyelectrolytes and UV-crosslinkable 4-arm polymers will be discussed. Minimal influence of covalent network's inclusion on PEC networks' equilibrium mesoscale structure will be demonstrated, conserving the hybrid gel's ability to encapsulate biomolecules and other charged cargo. At the same time, the hybrid hydrogels will be shown to possess superior mechanical properties, which are not achievable by either the PEC network or the covalent network. We will highlight marked improvements in the shear and the tensile strengths of the PEC hydrogels upon the incorporation of the covalent network, even as a minor component. Moreover, hybrid hydrogels will be demonstrated to exhibit enhanced resistance to salt addition and controllable swelling characteristics. The versatility of our hydrogel design platform will be established by demonstrating its compatibility with diverse covalent network formers, establishing a pathway for further broadening of the utility of the PEC hydrogels in diverse biomedical applications.