Finite element modelling of polymer gels that exhibit temperature induced volume phase transitions*

Temperature-induced volume phase transitions are one of the mechanisms by which large-scale deformations are manifested in biological systems. Polymer hydrogels that undergo spontaneous volume change upon variations in temperature are, therefore, perfect candidates for designing bioinspired self-oscillating materials that can reversibly sustain large deformations. Here, we present a computational framework to design the dynamical system based on chemical reactions, that undergoes large mechanical oscillations via external loading and thermally induced volume phase transitions, simultaneously. Specifically, our model is based on a nonlinear finite element framework that essentially combines reaction-diffusion phenomena with nonlinear elastic deformations of the gel under nonisothermal conditions. Through modelling and simulation, we capture large deformations and volume changes represented by swelling/shrinkage of the gels at varied temperatures. Our major findings not only complement the existing features of polymer gels and facilitates the design of a variety of complex biomimetic systems like thermo-sensitive actuators but also provides a mechanism to predict their complex nonlinear phenomena.