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Nano-Scale mechanics of Hydrogels: from all-atoms to coarse-grained molecular dynamics

Nima Rahbar (Worcester Polytechnic Institute), Hossein Salahshoor (WPI)

Advances in Nanocomposites for Thermal and Structural Applications

Tue 4:20 - 5:40

Barus-Holley 165

Recently, hydrogel have found to be promising biomaterials since their porous structure and hydrophilicity enables them to absorb a large amount of water. In this study the role of water and crosslinking density on the mechanical properties of hydrogel are studied using ab-initio molecular dynamics (MD) and coarse-grained simulations. Condensed-Phased Optimized Molecular Potential (COMPASS) and MARTINI force fields are used in the all-atom atomistic models and coarse-grained simulations, respectively. The crosslinking process is modeled using a novel approach by cyclic NPT and NVT simulations starting from a high temperature, cooling down to a lower temperature to model the curing process. Radial distribution functions for different water contents (20%, 40%, 60% and 80%) have shown the crosslinks atoms are more hydrophilic than the other atoms. Diffusion coefficients are quantified in different water contents and the effect of crosslinking density on the water diffusion is studied. Elasticity parameters are finally computed by constant strain energy minimization in mechanical deformation simulations. It is shown that an increase in the water content results in a decrease in the elastic.