Green and sustainable cellulose-based shape memory composites with excellent conductivity for temperature warning

Green and sustainable cellulose-based composites containing poly(ε-caprolactone) (PCL) with temperature-induced shape memory properties and conductivity performance are presented. The composites are fabricated by in situ polymerization of ε-caprolactone (ε-CL) monomer in three-dimensional porous cellulose gels, and then silver-porous cellulose gel/poly(ε-caprolactone) (Ag-Cell/PCL) composites are fabricated by depositing Ag onto the surface of porous cellulose gel/poly(ε-caprolactone) (Cell/PCL) composites. The addition of PCL not only improves the mechanical properties of the Cell/PCL composites but also endows them with excellent shape memory properties. The Cell/PCL composites exhibit a high shape-fixing rate (98.9%) and can recover to their original shape within 8 s without external force. In addition, the Ag-Cell/PCL composites show superior and stable conductivity under different bending angles. Finally, a temperature warning sensor with fast performance is successfully designed using Ag-Cell/PCL composites. This work provides a means to develop temperature warning systems based on shape memory polymers.