Deciphering the Rheological Properties of 3D Printed Semi-interpenetrated Hydrogels

Hydrogels have gained considerable scientific interest due to their unique properties and wide range of applications. Among the different types of hydrogels, semi-interpenetrating hydrogels (semi-IPNs), consisting of two independent but interacting physical and chemical networks, stand out for their combination of desirable properties, being especially in demand for biomedical applications. In this study, the physical network is generated by high molecular weight hyaluronic acid (HA), providing biocompatibility and bioactivity, whereas the chemical network of the hydrogel is formed by polyacrylamide (PAM), which provides mechanical strength and versatility. The objective of this research is to investigate the intricate interplay between PAM and HA through their rheological behaviour. For this purpose, the viscoelastic properties of these systems have been examined under linear and non-linear conditions. For a better understanding of these interactions, the effect of acrylamide concentration on the crosslink density as well as the HA concentration on the rheological response of the hydrogels has been explored. Additionally, VAT photopolymerization have been used to synthetize the PAM chemical network, allowing a high level of detail of the printed hydrogels.