Finite Element Modelling of Active Gels with non-Gaussian Compressible Polymeric Networks*

Metamorphosis in living systems has inspired the formation of complex 3D geometries from compact 2D domains, which can be replicated in soft materials through origami. Self-oscillating active polymer gels that exhibit chemo-mechanical transduction, can be enabling materials for designing self-folding structures. Here, we develop a generic theoretical framework, based on finite element method, to simulate mechanical response of both active and inactive polymer gels. Our approach combines the Flory Huggins theory to include polymer-solvent interactions and non-Gaussian statistical mechanics with limited polymer compressibility, to account for large elastic deformations in polymer gels. Through our 3D simulations, we capture chemo-mechanical oscillations in active polymer gels, which transform to neutrally swollen gel in the limiting case. Also, we investigate the role of friction between polymer and solvent on the dynamic behavior of polymer gels. Moreover, as a special case, we can simulate gels with incompressible polymer matrix and Gaussian chain statistics. Our findings can be useful for designing self-folding polymeric shapes to be used as smart miniaturized devices.