Dendrimer Ligand Directed Nanoplate Assembly

Abstract

Many studies on nanocrystal (NC) self-assembly into ordered superlattices have focused mainly on attractive forces between the NCs, whereas the role of organic ligands on anisotropic NCs is only in its infancy. Herein, we report the use of a series of dendrimer ligands to direct the assembly of nanoplates into 2D and 3D geometries. It was found that the dendrimer-nanoplates consistently form a directionally offset architecture in 3D films. We present a theory to predict ligand surface distribution and Monte Carlo simulation results that characterize the ligand shell around the nanoplates. Bulky dendrimer ligands create a nontrivial corona around the plates that changes with ligand architecture. When this organic–inorganic effective shape is used in conjunction with thermodynamic perturbation theory to predict both lattice morphology and equilibrium relative orientations between NCs, a lock-and-key type of mechanism is found for the 3D assembly. We observe excellent agreement between our experimental results and theoretical model for 2D and 3D geometries, including the percent of offset between the layers of NCs. Such level of theoretical understanding and modeling will help guide future design frameworks to achieve targeted assemblies of NCs.

Hard superellipse phases: particle shape anisotropy & curvature

“…The crystal has long-range 4-fold orientational order ( κ 4 ) and stretched 4-fold bond orientational order ( ψ s 4 ). Experiments on 2D assembly of rhombus micro- and nano-particles with rounded corners, 25 and possibly concave sidewalls, 28 have rhombic crystal structures matching the configuration described by the stretched four-fold symmetry ( ψ s 4 ). Such experiments involve different interactions due to spherical depletants and surface ligands, but show correspondence to our results for similar shapes.…”

“…23 Unintended curvature is often present in experiments due to particle fabrication limitations, which can produce significant effects in experimentally observed phase behavior. 24–28 In addition, realistic colloidal potentials generally include short-range soft repulsion and/or attraction, which can often be considered as effective hard particles with perturbation theories. 29 However, such realistic interactions can vary at particle corners and edges ( e.g.…”

Gaussian processes for autonomous data acquisition at large-scale synchrotron and neutron facilities

“…As an example experiment benefiting from these methods, we studied the self-assembly of nanoscale platelets [14]. Self-assembled superlattices inevitably exhibit a variety of domains of differing ordering, size and orientation.…”

Recent Notable Approaches to Study Self‐Assembly of Nanoparticles with X‐Ray Scattering and Electron Microscopy

“…DNA-based-small molecules-polymers are just a rough classification. Dendritic ligands [69][70][71] and surfactants like cetyltrimethylammonium bromide or chloride (CTAB and CTAC) are examples that do not perfectly match these categories. For instance, CTAC and CTAB are very important and commonly used ligands in the synthesis of spherical and anisotropic gold NPs in water and can stabilize even large nanostructures (> 100 nm) by forming a surfactant bilayer and providing electrostatic stabilization via their polar trimethylammonium termini.…”