Mechanical actuators, like muscles, are materials that can change their own macroscopic shape to perform mechanical work when submitted to an external stimulus, such as light irradiation. The resulting photoactuators (PA) are based on a variety of photoactive materials including gels, crystals, liquid crystal elastomers (LCE) or polymer films forming polymeric PA (PPA). This project focuses on PPAs, usually made of elastomers in which photoactive molecules are inserted. To optimize the PPA properties, a precise understanding of the behavior of these materials at all scales is necessary. PPAs are viscoelastic by nature and therefore the continuous scale modeling of their behavior requires the knowledge of some specific mechanical properties, like the time-dependent relaxation moduli G(t) and K(t). At the supramolecular scale, these relaxation moduli can be obtained by Molecular Dynamics (MD) simulations using the Green-Kubo relation [3]. However, for these materials, the G(t) and K(t) timescales far exceed the accessible timescales of MD (on the order of thousands of seconds vs. microseconds). This PhD work has thus two main objectives to reduce this gap :(i) temperature-accelerated dynamics, (ii) anisotropic coarse-grained (CG) simulations.