Hydrodynamics selects the pathway for displacive transformations in DNA-linked colloidal crystallites

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 13; pp. 4803 - 4808
• Main Authors: Jenkins, Ian C., Casey, Marie T., McGinley, James T., Crocker, John C., Sinno, Talid
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01-04-2014; National Acad Sciences
• Subjects: Anisotropy; Annealing; Cesium - chemistry; Chlorides - chemistry; Colloids - chemistry; Computer Simulation; Crystallites; Crystallization; Crystals; Deoxyribonucleic acid; Diffusion; DNA; DNA - chemistry; Eigenvectors; Fluid mechanics; Hydrodynamics; Kinetics; Mobility; Order disorder transformations; Particle diffusion; Particle energy; Particle interactions; Physical Sciences; Superlattices; Vibration; diffusionless transformations; DNA-mediated assembly; vibrational mode analysis
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1318012111

The degree to which DNA-linked particle crystals, particularly those composed of micrometer-scale colloids, are able to dynamically evolve or whether they are kinetically arrested after formation remains poorly understood. Here, we study a recently observed displacive transformation in colloidal binary superlattice crystals, whereby a body-centered cubic to face-centered cubic transformation is found to proceed spontaneously under some annealing conditions. Using a comprehensive suite of computer simulation tools, we develop a framework for analyzing the many displacive transformation pathways corresponding to distinct, but energetically degenerate, random hexagonal close-packed end states. Due to the short-ranged, spherically symmetric nature of the particle interactions the pathways are all barrierless, suggesting that all end states should be equally likely. Instead, we find that hydrodynamic correlations between particles result in anisotropic mobility along the various possible displacive pathways, strongly selecting for pathways that lead to the fcc-CuAu-I configuration, explaining recent experimental observations. This finding may provide clues for discovering new approaches for controlling structure in this emerging class of materials.