Solar Light Responsive Polymer Composites with Three Shape-Memory Effects

Solar light responsive polymer composites which can deform their shape according to the variation in sunlight power density are prepared by incorporating the solar light photothermal filler of Sm_0.5Sr_0.5CoO₃ (SSC) into crosslinked poly[ethylene-ran-(vinyl acetate)] (EVA). Dual shape-memory effect, temperature-memory effect, and reversible bidirectional shape-memory effect are all achieved in such EVA-SSC composites. Dual shape-memory effect with fixation ratio over 99% and recovery ratio over 95% is presented, while the responsive power density is adjusted from 0.4 to 0.1 w cm^-2 by simply decreasing the programming temperature from 140 to 50 °C. Furthermore, during a cyclic variation in power density from 0 to 0.3 w cm^-2 and back to 0 w cm^-2 in 6 min, the composite specimens show a reversible angle deformation. Finally, a sunlight-adaptive circuit switch is demonstrated using such composites, automatically turning off the LED lamp and turning on the motor fan according to the sunlight power density. Solar light responsive polymer composites which can change their shape according to the variation in sunlight power density are achieved. The incorporation of Sm_0.5Sr_0.5CoO₃ into crosslinked poly[ethylene-ran-(vinyl acetate)] generates good photothermal property, dual shape-memory, temperature-memory, and reversible shape-memory effects. The prepared materials have potential applications in sunlight-adaptive instruments, such as the demonstrated circuit switch.