Figure 5. The photothermal performance of double-sided heterochromatic nano wrinkled photothermal membranes. (a) The original PLLA membranes before sunlight irradiation. (b) The original PLLA membranes after sunlight irradiation. (c) The treated PLLA membranes without CS and MWCNTs before sunlight irradiation. (d) The treated PLLA membranes without CS and MWCNTs after sunlight irradiation. (e) The photothermal comparisons of membranes in different CS/MWCNTs concentrations. (f) The photothermal comparisons of dark side and light side. (g) The photothermal comparisons of membranes in different sunlight irradiation. (h) The photothermal performance of membranes on low-temperature glass substrates (-20 ˚C) (Top left, original concentration light side; top right, original concentration dark side; bottom left, C/2 concentration dark side; bottom right, C/4 concentration dark side). (i, j) The photothermal comparisons of membranes before (i) and after (j) sunlight irradiation, the blue triangle represents the location of the lowest temperature on the line, the red triangle represents the location of the highest temperature on the line. (k) The temperature distribution on the line of (i and j).