The density distributions of the head part, ϕ_h, of the (20/80) amphiphiles with fixed volume fraction f = 0.3, corresponding to different side lengths L ((a) L = 28, (b) L = 40, (c) L = 48, and (d) L = 56) in Fig. 1(a). The white squares schematically denote the square-shaped particles with different sizes.