Polylactic-Acid Having MoS2 Particles for Reversible Bilayer Actuators

Polylactic acid (PLA) composites having 1 wt% of MoS₂ particles are prepared by solvent (SM) and melt mixing (MM) methods and their main thermal and mechanical properties are characterized. Coated films from SM samples and 3D-printed filaments from MM samples are tested as active layers in reversible bilayer actuators using a paper sheet as a passive layer. The thermal properties depend on the method used to prepare the composites with MM samples presenting a cold crystallization and a glass transition during the first and second heating and SM samples displaying a standard melt process during the first heating and a small cold crystallization and a glass transition during second heating. Regarding the stiffness, MoS₂ increases this property confirming its reinforcement effect. Both kinds of bilayers show reversible actuation under heating either by putting the actuator on a hot plate or by remotely irradiating the sample with near-infrared light (NIR). Under NIR, the 3D printed composites present a much higher actuation. The higher remote actuation in composited bilayers is explained by the NIR light absorption of the MoS₂ photoactive particles. This actuator can be used for the design of a smart façade or blind that closes under NIR stimulus.