Mesoscale Modeling of Swelling Kinetics of Hydrogels

Swelling kinetics of hydrogels critically determines whether gels can reach the thermodynamically favored states, thus plays a vital role in synthesis and processing as well as the materials properties of gel systems. To provide a microscopic understanding of the dynamics of gel swelling, we combine the many-body dissipative particle dynamics (MDPD) with Monte Carlo (MC) method to capture solvent exchange and dynamic motion of networks under a constant solvent chemical potential, constant pressure, constant temperature ( ensemble. To achieve pressure control, we apply a “Langevin piston” method to an extensive system. The chemical potentials equilibrium is reached by MC insertions and deletions of solvent. Our result shows the gel swelling as a result of the balance between the osmotic pressure and elastic force originated from the deformation of the network. We explore the effects of density of crosslinks, network topology, and bond styles on the equilibrium states of the hydrogels. Our model reveals the swelling kinetics of gels under experimentally relevant conditions in great detail. Moreover, this simulation tool is not limited to hydrogels but can be extended to simulate a wide range of complex fluid systems in chemical equilibrium under isothermal-isobaric condition.