(197p) Modeling Elastic Properties of Polyacrylamide Hydrogel Depending on Effective Structures

Hydrogels have attracted significant interest in a range of applications due to their complex physical and chemical structures, which enable multiscale interactions. Polyacrylamide hydrogels, in particular, offer a wide range of mechanical properties and exhibit biocompatibility and versatile customization. However, simulating the macroscale properties of hydrogels is challenging due to the intricate multiscale interactions that occur within them. To optimize the effect of each scale while considering the trade-off relationship among them for numerical methods, it is crucial to understand how multiscale structures influence the mechanical properties of hydrogels. In this study, we present a coarse-grained molecular dynamics approach for predicting the elastic modulus of hydrogels based on effective chain lengths of defect-less network structures. We utilized a mixed force-field that accounted for both bonded and non-bonded interactions, with the bonded potentials being extracted from atomistic simulation results and the MARTINI coarse-grained force field used to simulate the non-bonded parts of the hydrogel. Our model utilized coarse-grained potentials to depict the initial deformation of uniaxial tensile, indicating Young’s modulus, while also reflecting the effects of strain rates and swelling ratio on the modulus. Especially, strain rates should be treated with a caution due to rate differences of about 10 to the power of 6 to 10 per second, which could even be related to bond relaxation level inducing an exponential increase in modulus. Plus, the model was constructed with isotropic structures referencing experimental pre-gel conditions, being able to follow elastic properties’ propensity depending on cross linker density.Our findings demonstrate the potential of using coarse-grained molecular dynamics methods to model and predict the elastic properties of hydrogels, despite the inherent randomness in their physical and chemical structures. Moreover, this approach could serve as a foundation for the development of various applications through versatile additives.