Due to the size- and shape-dependent properties, nanoparticles have been successfully used as functional building blocks to fabricate 1-3D ordered assemblies for the development of artificial metamaterials. At ambient pressure, entropy driven self-assembly of monosized or binary nanoparticles generally results in polycrystalline 2- or 3D close-packed arrangements, and extensive efforts have been made to develop structural perfection of nanoparticle arrays or ‘single crystal-like’ domain structures with precise long range order for their definite advantages for electron transport. To date, fabrications of ordered nanoparticle assemblies have been relied on specific interparticle chemical or physical interactions such as van der Waals interactions, dipole-dipole interaction, chemical reactions, etc. Recentlywe have discovered a pressure-induced assembly method to engineer nanoparticle stability and to fabricate new nanoparticle architectures without relying on specific nanoparticle interactions.We show that under a hydrostatic pressure field, the unit cell dimension of a 3D ordered nanoparticle arrays can be manipulated to reversibly shrink, allowing fine-tuning of interparticle separation distance. Under a uniaxial pressure field, nanoparticles are forced to contact and coalesce, forming hierarchical nanostructures. Depending on the orientation of the initial nanoparticle arrays, 1-3D ordered nanostructures including nanorod, nanowire, and nanoporous network can be fabricated through the pressure-induced self-assembly method. Guided by computational simulations, we were able to rationalize the pressure-induced self-assembly of nanoparticle arrays for predictable nanostructures. Moreover, we discovered for the first time a transition from an ordered polycrystalline nanoparticle mesophase to quasi-single crystalline nanoparticle lattices induced by PDA process. Exerting pressure-dependent control over the structure of nanoparticle arrays provides a unique and robust system to understand collective chemical and physical characteristics and to develop novel electronic and photonic behavior for energy transduction related applications.<br/><br/><br/>

Nanoparticles under high pressure: Stability and formation of active nanostructures

2019 Spring National Meeting

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