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 Sm0.5Sr0.5CoO3 (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 degrees 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.