Shape memory actuation in liquid-crystalline epoxies and their nanocomposites

Thermally triggered shape-memory polymers are materials based on exploiting one or more phase transitions, such as glass, melting, or clearing transition, to give shape-memory effect. Among shape-memory polymers, liquid crystalline elastomers (LCEs) are good candidates due to the synergistic effect of the ordered liquid crystalline phase and the lightly cross-linked polymeric structure, responsible for their programming and recovering behavior. Herein, the synthesis and characterization of shape-memory epoxy-based LCEs incorporating compatibilized carbon nanoparticles is presented. The general thermal, morphological and viscoelastic properties of the realized nanocomposite films are reported and discussed, with a particular concern on the thermo-mechanical actuation. Results demonstrate that the soft-elastic response, and consequently, the thermal actuation of the LCE-based nanocomposites is improved by the presence of nanofillers, and strictly related to the microstructure generated. Tunable thermomechanical properties of these systems make them potentially suitable for a variety of applications ranging to robotics, sensing and actuation, and artificial muscles.