title: Charge regulation as a stabilization mechanism for shell-like assemblies of polyoxometalates.
abstract: We show that the equilibrium size of single-layer shells composed of polyoxometalate macroions is inversely proportional to the dielectric constant of the medium in which they are dispersed. This behavior is consistent with a stabilization mechanism based on Coulomb repulsion combined with charge regulation. We estimate the cohesive energy per bond between macroions on the shells to be approximately -6kT. This number is extracted from analysis based on a charge regulation model in combination with a model for defects on a sphere. The value of the cohesive bond energy is in agreement with the model-independent critical aggregate concentration. This observation points to a new class of thermodynamically stable shell-like objects. We point out the possible relevance our findings have for certain surfactant systems.
authors.affiliation: Van 't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Aletta A
authors.initials: AA
authors.lastname: Verhoeff
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Kistler
authors.forename: Anish
authors.initials: A
authors.lastname: Bhatt
authors.forename: Joe
authors.initials: J
authors.lastname: Pigga
authors.forename: Jan
authors.initials: J
authors.lastname: Groenewold
authors.forename: Mark
authors.initials: M
authors.lastname: Klokkenburg
authors.forename: Sandra
authors.initials: S
authors.lastname: Veen
authors.forename: Soumyajit
authors.initials: S
authors.lastname: Roy
authors.forename: Tianbo
authors.initials: T
authors.lastname: Liu
authors.forename: Willem K
authors.initials: WK
authors.lastname: Kegel