2022 Annual Meeting
Mechanical and Rheological Properties of Inorganic:Organic Hybrid Hydrogels
Hydrogels are soft, water-swollen polymer networks of interest for applications in tissue- engineering, drug delivery, and increasingly, bioelectronics. Recent efforts to alter the relevant mechanical properties of gels (e.g., shear modulus, strain at break, and toughness) have centered on crosslinking water-soluble polymers via metal ions. Here, we demonstrate that inorganic:organic hybrid hydrogels based on poly(vinyl alcohol) (PVAl) and titanium oxide hydrates as a crosslinker can be designed in a controlled fashion to form environmentally responsive polymer networks with biomimetic mechanical properties. By altering the titanium oxide hydrates content, as well as varying the PVAl molecular weight and solution concentration, we show based on oscillatory rheometry data how gel stiffness is controlled by both the metal- ligand coordination to the polymer, which leads to chemical crosslinking, as well as the density of PVAl entanglements per chain (i.e., âphysical crosslinkingâ). Unexpectedly, our results also suggest that the formation of a PVAl-titanium-oxide hydrates network is sensitive to the pH of its aqueous environment, even at constant titanium oxide hydrate content. Careful manipulation of both titanium oxide hydrate content and environmental pH can, thus, be used to produce homogeneously crosslinked gels with desired elastic and storage moduli on par with a range of soft tissues.