Ridge formation of charged end group ligands grafted on faceted nanoparticle

We have investigated the conformations of charged end group ligands grafted on icosahedral nanoparticles, using a coarse-grained molecular dynamics approach. Due to a competition between the electrostatic repulsion and the hydrophobic ligand-ligand attraction, the ligand coatings form a variety of different conformations. These conformations have been compared with the case of non-charged grafted ligands. We have found that the electrostatic interaction between the charged ends drives the formation of a ridge-like structure of the ligands, which makes the nanoparticle surface highly anisotropic. We argue that the ridge-like ligand structure induces controllable directional interaction between the nanoparticles, and can drive the self-assembly of the nanoparticles into crystalline structures.