Fig. 2. Effect of the adhesive layer and peeling parameters on shape morphing of plastic films.

a Films peeled with higher peeling forces exhibited larger curvatures. Inset: optical photograph of a peeled PTFE film (37 μm thick, peeling angle of 90° and peeling speed of 10 mm/s). Curvature is defined as 1/r, where r is the radius of the circle. b Graph showing films that were peeled faster (measured as speed in mm/s) required larger peeling forces (green curve) and they resulted in more curly films (black dots and red curve). The theoretical results are quantitatively consistent with the experimental ones. c Graph of curvature and peeling force versus thickness of the adhesive layer (30–200 μm examined) showing films on thicker adhesives required slightly higher peeling forces to detach but they formed less curly shapes (lower curvature). d Graph showing plastic film thickness did not affect peeling forces (green curve) but thicker films displayed lower curvatures after peeling (black dots and red curve). e Curvature of the peeled film (black dots and red curve) increased as peeling angle increased from 30° to 180° and the peeling force (green curve) has a minimum at about 130°. f Graph of the pitch (black curve and red curve) and diameter (blue curve) of peeled films versus the deviation angle showing a positive deviation angle leads to right-handed helices, while a negative deviation angle results in left-handed helices. Larger deviation angles lead to helices with larger pitches. Insets: representative photographs of left- and right-handed helices. The pitch, P, is calculated by P = πd tan δ. The data in a-f are presented as mean ± s.d. of n ≧ 3 independent measurements. Source data are provided as a Source Data file.