Fig. 3: Nanometer precision in size and shape of patches from asymmetric grafting.

a Representative TEM images of patchy prisms. The patches are color-coded to their local thickness t. b Representative simulated patchy prisms obtained at the conditions corresponding to (a). c Plots showing patch area A (in 2D projected TEM view) decreases with increasing α (left, at fixed T = 90 °C) and T (right, at fixed α = 50 nM) in log‒log scale with power law fitting. Mean values are shown and error bars represent the standard deviation. d Plots of l and \({t}_{{{{{{\rm{m}}}}}}}\) as a function of (left) α and (right) T from experiments (symbols: mean values and standard deviation) overlaid with predictions from simulation (solid lines). e The contour of the topmost patch in (a), color-coded by local surface curvature. Local patch width \(w(x)\) is defined as a function of x, an axis vector connecting from the center to each tip of a prism. The position of the tip refers to x = 0. Note that \(w(x)\) at x < 0 region was measured by subtracting the prism width \(p(x)\) from the width of patch contour at x. f Plot of \(w(x)\) (the standard deviation of 10 representative \(w(x)\) as colored shadow for the prisms synthesized at the reaction conditions listed in (a) overlaid with the corresponding predictions from theory (dotted lines). Note that condition iv in (a) has a coexisting range of flattened and bulky patch shapes categorized into thin, (iv_thin), medium (iv_medium), and thick (iv_thick). g Schematic showing the pendant-like shape of large patches governed by the balance of three interactions: interaction between polymer and 2-NAT-coated prism tip (\({E}_{{{{{{\rm{int}}}}}}}\)), attraction between all monomers presented within the layer (\({E}_{{{{{{\rm{att}}}}}}}\)), and surface tension cost from contact with the surrounding solvent (\({E}_{{{{{{\rm{surf}}}}}}}\)). Scale bars: 10 nm (a), 5 nm (e).