Optimization of photomobile polymer films' production by ZnO nanoparticles and silver nanocuboids doping.

Among smart materials, photo-mobile polymers (PMPs) based on liquid crystals are the most promising in the field of photo-responsive actuators. Indeed, they are realized with a mixture of liquid crystals containing azobenzene moieties able to photo-isomerize from $trans$ to $cis$ under UV light. Photoisomerization leads to a macroscopic bending of PMPs transforming light into mechanical energy. To enhance the PMPs actuation, a novel liquid crystal nanocomposite is proposed in the frame of the UE FET PULSE-COM and Eureka investor funded POC ALICE projects. In our work, we used a facile and effective approach to enhance the quantum yield of azobenzene and to extend its wavelength sensitivity by doping the PMP matrix with either ZnO NPs or Ag NPs. These doped PMP films showed faster and more significant bending under both UV as well as visible and NIR light regardless of whether it was coherent, incoherent, polarized and unpolarized irradiation. This demonstrates the potential of these doped PMP films for producing sunlight-sensitive devices such as photomechanical actuators and a new generation of harvesting systems.