Investigating the relationships between composition, processing, and mechanics in PEGDA-PEGMEA hydrogels*

Poly(ethylene glycol) diacrylate (PEGDA) hydrogels have been widely used in biomedical applications because they are biocompatible and can be easily fabricated via photocrosslinking. To meet various application needs, it is crucial to precisely control the mechanical properties of PEGDA hydrogels. However, this is a challenging task due to the structural heterogeneity of PEGDA hydrogel networks, as classical theories developed for different polymer network types are not suited to provide accurate predictions. In this work, we systematically study a series of hydrogels based on PEGDA and monofunctional poly(ethylene) methyl ether acrylate (PEGMEA) with different molecular weights and precursor weight fractions, while maintaining a constant mole ratio between the two monomers. Based on uniaxial compression and swelling data, in combination with our understanding of network topology from analysis of polymerization kinetics, we develop a model that relates molecular characteristics of network components and processing parameters to the mechanical properties of PEGDA-based hydrogels. The potential of the new model for tailoring the hydrogel's mechanical properties will be discussed.