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Title: Spontaneous phase separation during self-assembly in bi-dispersed spherical iron oxide nanoparticle monolayers

Recent developments in the synthesis of iron oxide nanoparticles have resulted in the ability to fabricate roughly spherical particles with extremely high size uniformity (low polydispersity). These particles can form self-assembled monolayer films at an air-water interface. When the polydispersity of the particles is low, these monolayers can be well-ordered over a length scale dozens of times the particle size. The van der Waals force between the particles is what drives this self-assembly. Through the use of Grazing Incidence X-Ray Diffraction we demonstrate that, when these films are formed at the liquid surface from bi-dispersed solutions containing 10 and 20 nm spherical particles suspended in chloroform, the particles phase separate into well-ordered patches during the self-assembly process. Furthermore, the domain sizes of these phase separated regions are at most 2–3 times smaller than that of a film comprising only mono-dispersed particles and their degree of disorder is comparable. This is shown for multiple solutions with differing ratios of 10 and 20 nm particles.
Authors:
; ;  [1] ; ;  [2]
  1. Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)
  2. Center for Advanced Radiation Sources (CARS), University of Chicago, Chicago, Illinois 60637 (United States)
Publication Date:
OSTI Identifier:
22398920
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHLOROFORM; COMPARATIVE EVALUATIONS; FILMS; INTERFACES; IRON OXIDES; LIQUIDS; MATHEMATICAL SOLUTIONS; NANOPARTICLES; PARTICLE SIZE; SPHERICAL CONFIGURATION; SURFACES; SYNTHESIS; VAN DER WAALS FORCES; X-RAY DIFFRACTION