Hydrodynamic and frictional modulation of deformations in switchable colloidal crystallites

Abstract

Displacive transformations in colloidal crystals may offer a pathway for increasing the diversity of accessible configurations without the need to engineer particle shape or interaction complexity. To date, binary crystals composed of spherically symmetric particles at specific size ratios have been formed that exhibit floppiness and facile routes for transformation into more rigid structures that are otherwise not accessible by direct nucleation and growth. There is evidence that such transformations, at least at the micrometer scale, are kinetically influenced by concomitant solvent motion that effectively induces hydrodynamic correlations between particles. Here, we study quantitatively the impact of such interactions on the transformation of binary bcc-CsCl analog crystals into close-packed configurations. We first employ principal-component analysis to stratify the explorations of a bcc-CsCl crystallite into orthogonal directions according to displacement. We then compute diffusion coefficients along the different directions using several dynamical models and find that hydrodynamic correlations, depending on their range, can either enhance or dampen collective particle motions. These two distinct effects work synergistically to bias crystallite deformations toward a subset of the available outcomes.

In situ observation of coalescence of nuclei in colloidal crystal-crystal transitions

“…This is because the micron-sized particles can be directly visualized and their motions tracked inside the bulk using optical microscopy [9]. C-c transitions in colloidal systems can be induced by applying electric or magnetic fields [10,11], or by tuning particle size and interaction [12][13][14][15][16][17][18]. To date these studies have revealed a rich variety of kinetic processes such as martensitic transformations within small crystallites [15] and under external stress [13,19], two-step diffusive nucleation with intermediate liquid states [12], forward-martensitic-and-reverse-diffusive transitions [11], and softness-dependent transition pathways [14,20].…”

“…Notably, however, the previous studies on the nucleation and growth focus on the evolution of an individual nucleus (stages I and II) [10][11][12][13][14][15][16][17][18]. The coalescence of nuclei (in stage III) has not been elucidated.…”

Temperature-Controlled Reconfigurable Nanoparticle Binary Superlattices

“…In particular, the so-called diffusionless or Martensitic transformations, where particles only undergo local structural rearrangements, are an important category of solid–solid transitions. While the diffusionless transformations between BCC and FCC are well recognized and important in atomic materials, their existence in self-assembled colloidal systems are less explored. , Recently, it has been suggested that diffusionless transformations, from BCC-CsCl to FCC-CuAu in 3D ,− and square to hexagonal in 2D, , also exist in DNA-functionalized particles (DFPs), , generating considerable intrigue about the underlying phenomena. The emergence of this behavior in DFPs may result from a unique advantage in the ability to tune interparticle interactions between DFPs by choosing appropriate DNA sequences. − However, mechanistic details of how crystals transform and critical controlling parameters for these transformations in DFP systems are poorly understood.…”

“…Computer simulations can provide essential information about the role of thermodynamics versus kinetics in such transformations that cannot be revealed by experiments alone. For example, Sinno and co-workers provided important insights regarding the influence of hydrodynamic interactions on structural selection. , Herein, we study the solid–solid transformation from the thermodynamic perspective by performing molecular dynamics (MD) simulations and theoretical calculations. We find that the BCC-CsCl to FCC-CuAu transformation in our MD simulations is governed by thermodynamic rules and can be controlled reversibly as a function of temperature.…”

Metallization of colloidal crystals

“…The small particle is represented by a central sphere (purple) and explicitly modeled grafted chains (white), each of which has an interactive terminus (orange) that is radially attractive only to large particles. The generality of the model implies that we can represent a variety of experimental systems [5,6,[20][21][22][23], and the tunability of NPs enables us to find a rich variety of lattices and multiple types of delocalization transitions.…”