Characterizing mechanical and structural properties of degrading tetra-PEG hydrogels

Controlling degradation of polymer networks is critical for a broad range of applications. Photo-controlled degradation permits spatially-resolved dynamic control of materials properties, in particular mechanical properties of hydrogel-based materials. We use our recently developed dissipative particle dynamics (DPD) framework that captures degradation of hydrogels at the mesoscale to characterize variations in network elasticity as degradation proceeds. Breaking elastically active network strands during degradation leads to a decrease in elastic modulus. We quantify the elastic modulus of degrading gels as a function of the proximity to the reverse gel point. Further, degrading hydrogels are highly heterogeneous systems; hence we quantify the structural and dynamic heterogeneities upon approaching the reverse gel point. Our results allow one to quantify mechanical properties of degrading hydrogel material and could provide guidelines for future design of degrading materials with dynamically controlled mechanical properties.