MIT Researchers Demonstrate Flexible Ligands for Nanoparticle Assembly
Researchers show that flexible ligands can enable programmable material structures, challenging traditional assumptions in nanotechnology.
Researchers from MIT have demonstrated that flexible, electrostatically active isotropic nanoparticles can be assembled into programmable material structures. This work, published in Nature Materials, reveals that valency does not need to be dictated by particle geometry but can emerge spontaneously during assembly. By using deformable ligand coronas, the ligands can reconfigure to align along interparticle interfaces, effectively generating valency.
Ligand Flexibility in Nanoparticle Assembly
The study shows that increasing the deformability of ligands lowers lattice coordination numbers. This finding challenges the long-held belief that rigid ligands are necessary for stable nanoparticle assembly. Instead, the researchers found that flexible ligands allow for the creation of less densely packed lattices with lower symmetry than previously predicted from hard-sphere packing models. This approach opens new avenues for designing nanostructures with tailored properties.
Implications for Material Design
By utilizing gold nanoparticles functionalized with flexible polyethylene glycol (PEG) chains, the researchers were able to control the number and orientation of bonds formed between particles. The flexibility of the PEG ligands allowed for localized clustering at points of direct contact, which naturally limited excessive networking. This innovative method enables the creation of highly ordered crystalline superlattices with unique geometries and reduced coordination numbers. Future work will explore other combinations of elements and ligand types to further enhance control over nanoscale architectures and their macroscopic properties.
