(209o) Modeling Responsive Hydrogels Using Dissipative Particle Dynamics (DPD)

A responsive hydrogel is composed of a large network of polymer chains that can expand (swell) and contract (de-swell) when an external stimulus, such as from changes in temperature, concentration, pH, light intensity, is applied. Responsive hydrogels find an increasing number of applications in engineering, ranging from drug delivery to soft robotics. We develop a model based on dissipative particle dynamics (DPD) to simulate responsive hydrogels submerged in a viscous solvent. In our model, the polymer chains are represented by randomly interconnected elastic filaments. The elastic filaments themselves are composed of DPD particles connected by stretching and bending potentials and interact with the solvent via DPD potentials. To model the swelling and de-swelling of the gel network, we dynamically alter the equilibrium length of the filaments. We validate this model by comparing gel swelling kinetics with theoretical predictions and use it to study a variety of systems including swelling of differently shaped particles and capsules and dynamics of hydrogel micro-swimmers.