Fig. 2: Quantitative control of the asymmetric grafting.

a Schematic of the theoretical model of polymer chain grafting. Green dotted arrows (left) denote adsorption sites (tip area with the light blue shadows) on prisms for incoming polymer chains, either sites already occupied by other polymer chains or unoccupied. Zoomed-in view (middle) shows the theoretical model of grafted polymer chains (end-to-end distance R) on the tip of prisms, as a function of surface position Ω. b, c Schematics showing the effect of increasing (b) temperature T and (c) ligand concentration α, the ratio of 2-NAT molar concentration to the optical density of the prism suspension at its maximum extinction wavelength. d, f TEM images of patchy prisms at (d) increasing T (α = 50 nM, fixed) and (f) increasing α (T = 90 °C, fixed). e, g Histograms of NPs with the patch count n synthesized from the corresponding conditions presented in (d) and (f), respectively. Counted from 150‒220 NPs per condition. Shading colored to n as noted in the legend. ‘Ot.’ in legend refers to the prisms with at least one prism edge coated with polymer patch. h Maps of 3D grafting probability \({p}_{{{{{{\rm{graft}}}}}}}\) at varied χ values. i Plots of patch profile \({p}_{{{{{{\rm{\theta }}}}}}}\) during the grafting simulation time \({t}_{{{{{{\rm{graft}}}}}}}\). The \({p}_{{{{{{\rm{\theta }}}}}}}\) is obtained by projecting \({p}_{{{{{{\rm{graft}}}}}}}\) over 2D projected prism contour and integrating it as a function of angle θ (defined in (a)). We define the grafting “time” \({t}_{{{{{{\rm{graft}}}}}}}\) as the ratio of current grafting density to the targeted grafting density of the simulation. j Phase diagram of patch count n (shading colored to n as noted in the legend) across the parameter space: grafting temperature T, chain length N, and ligand concentration α. The phase diagram is partitioned to different colored regions following simulation results. The black lines are phase boundaries predicted by theory. The cyan-colored open symbols in the phase diagram correspond to the experimental results labeled in (d) and (f). Scale bars: 100 nm.