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Liquid-cell Transmission Electron Microscopy for Tracking Self-assembly of Nanoparticles
Published on: October 16, 2017
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Reversible Diffusionless Phase Transitions in 3D Nanoparticle Superlattices
Daryl W Yee1, Margaret S Lee1, Joyce An1
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
Journal of the American Chemical Society
|March 10, 2023
Summary
Polymer brush-grafted nanoparticles form ordered superlattices. Researchers discovered a reversible phase transition between face-centered-cubic and body-centered-cubic structures, enabling control over microstructure.
Area of Science:
- Materials Science
- Nanotechnology
- Crystallography
Background:
- Nanocomposite tectons (NCTs) are polymer brush-grafted nanoparticles that self-assemble into ordered nanoparticle superlattices (NPSLs) via supramolecular interactions.
- Thermal annealing typically leads to well-defined unit cell symmetries in NPSLs.
Purpose of the Study:
- To demonstrate control over NCT lattice microstructure by balancing enthalpic and entropic factors during crystallization.
- To investigate the phase transition behavior of NCTs in response to solvent-induced changes in polymer brush conformation.
Main Methods:
- Assembly of unary NCT systems using small molecules to mediate supramolecular bonding.
- Induction of phase transitions by transferring FCC lattices to solvents that cause polymer brush collapse.
- Characterization of microstructural features, including transformation twinning.
Main Results:
- NCTs initially form face-centered-cubic (FCC) lattices in favorable solvents.
- A reversible, diffusionless phase transition from FCC to body-centered-cubic (BCC) lattices occurs upon transfer to a collapsing solvent.
- BCC superlattices exhibit transformation twinning, similar to martensitic alloys, while retaining the FCC crystal habit.
Conclusions:
- Control over NPSL microstructure is achievable by manipulating assembly and processing conditions.
- The observed diffusionless phase transformation offers a novel mechanism for creating unique microstructures in nanoparticle assemblies.
- NPSLs can serve as model systems for studying microstructural evolution and as analogues for atomic crystalline materials.
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