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Updated: Mar 29, 2026

Liquid-cell Transmission Electron Microscopy for Tracking Self-assembly of Nanoparticles
Published on: October 16, 2017
Self-assembly of like-charged nanoparticles into microscopic crystals
Pramod P Pillai1, Bartlomiej Kowalczyk2, Bartosz A Grzybowski3
1Department of Chemistry and Department of Chemical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois, USA and Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.
Abstract:
Like-charged nanoparticles, NPs, can assemble in water into large, faceted crystals, each made of several million particles. These NPs are functionalized with mixed monolayers comprising ligands terminating in carboxylic acid group ligands as well as positively charged quaternary ammonium ligands. The latter groups give rise to electrostatic interparticle repulsions which partly offset the hydrogen bonding between the carboxylic acids. It is the balance between these two interactions that ultimately enables self-assembly. Depending on the pH, the particles can crystallize, form aggregates, remain unaggregated or even - in mixtures of two particle types - can "choose" whether to crystallize with like-charged or oppositely charged particles.
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