Figure 4: Controlling of superstructure in hydrogels by using different masks.

(a) Images of the as-prepared gels taken by digital camera to show the gel appearances and patterns. The masks used for photolithography are shown in the top of each column, where the masked regions are black and unmasked regions are white. Scale bar, 5 mm. (b) Images of swollen gels observed under circular polarized light. The oriented domains show strong birefringence. Scale bar, 1 cm. (d) The yellow rectangle regions shown in row (b) were observed by crossed polarizers with 530-nm tint plate to determine the molecular orientation. Scale bar, 1 mm. c,e Schematic illustrations of the orientation of PBDT molecules within the swollen gel, where the orange, blue and green bars represent highly ordered orientation. The grey regions in e correspond to the regions of masks, where the central parts of gels have high swelling. Size of mask patterns: (I) width of masked stripes and distance between stripes are 1.5 and 0.5 mm, respectively. (II) Width of masked stripes and distance between stripes are 2.0 and 0.6 mm, respectively. (III,IV) Diameter of dots and distance between dots are 2.0 and 0.6 mm, respectively. (V) Width and length of branch line are 1.5 and 4.0 mm, respectively.