title: Self-assembly of like-charged nanoparticles into microscopic crystals.
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.
authors.affiliation: Department 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.
authors.forename: Pramod P
authors.initials: PP
authors.lastname: Pillai
authors.affiliation: Department of Chemistry and Department of Chemical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois, USA and 3M Purification Inc., 400 Research Parkway, Meriden, CT 064503, USA. bkowalczyk@mmm.com.
authors.forename: Bartlomiej
authors.initials: B
authors.lastname: Kowalczyk
authors.affiliation: IBS Center for Soft and Living Matter and the Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea. grzybor72@unist.ac.kr.
authors.forename: Bartosz A
authors.initials: BA
authors.lastname: Grzybowski