Structural diversity in binary superlattices self-assembled from polymer-grafted nanocrystals

Ye, Xingchen; Zhu, Chenhui; Ercius, Peter; Raja, Shilpa N.; He, Bo; Jones, Matthew R.; Hauwiller, Matthew R.; Liu, Yi; Xu, Ting; Alivisatos, A. Paul

doi:10.1038/ncomms10052

Cited by 222 publications

(290 citation statements)

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“…Polystyrene-grafted Au (PS-Au) nanocrystals were synthesized following a previously published procedure (18). Thiol-terminated atactic polystyrene was introduced postsynthetically to replace the native oleylamine ligands on as-synthesized Au nanocrystals.…”

Section: Resultsmentioning

confidence: 99%

“…Recent advances in the synthesis of exceedingly monodisperse polymer-grafted nanocrystals have enabled the fabrication of one-component and binary nanocrystal superlattices with wellcontrolled long-range order (18). The nanocrystals used in these superlattices are grafted to short strands of polymer (∼10-200 monomers), and combine the structural versatility of polymers with the architectural control of superlattices.…”

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Tolerance to structural disorder and tunable mechanical behavior in self-assembled superlattices of polymer-grafted nanocrystals

Koshy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Large, freestanding membranes with remarkably high elastic modulus (>10 GPa) have been fabricated through the self-assembly of ligand-stabilized inorganic nanocrystals, even though these nanocrystals are connected only by soft organic ligands (e.g., dodecanethiol or DNA) that are not cross-linked or entangled. Recent developments in the synthesis of polymer-grafted nanocrystals have greatly expanded the library of accessible superlattice architectures, which allows superlattice mechanical behavior to be linked to specific structural features. Here, colloidal self-assembly is used to organize polystyrene-grafted Au nanocrystals at a fluid interface to form ordered solids with sub-10-nm periodic features. Thin-film buckling and nanoindentation are used to evaluate the mechanical behavior of polymer-grafted nanocrystal superlattices while exploring the role of polymer structural conformation, nanocrystal packing, and superlattice dimensions. Superlattices containing 3-20 vol % Au are found to have an elastic modulus of ∼6-19 GPa, and hardness of ∼120-170 MPa. We find that rapidly self-assembled superlattices have the highest elastic modulus, despite containing significant structural defects. Polymer extension, interdigitation, and grafting density are determined to be critical parameters that govern superlattice elastic and plastic deformation.elasticity | buckling | nanocomposite | thin film | nanoindentation N anocrystal superlattices are ordered arrays of ligand-stabilized colloidal nanocrystals with unique thermal (1, 2), optical (3, 4), and electronic (5, 6) properties due to the nanoscale dimensions and periodic spacing of the inorganic crystals. Nanocrystal superlattices also exhibit superior mechanical performance: superlattice elastic modulus has been shown to rival that of lightweight structural composites (>10 GPa), and superlattice membranes are capable of withstanding repeated indents to large displacements (7)(8)(9). This is all the more remarkable because mechanical cohesion in the superlattices is attributed to van der Waals interactions between ligands on neighboring nanocrystals (10, 11), which are weak enough that the ligands are liquid at room temperature when not attached to nanocrystals. Superlattice strength and stiffness can be further elevated to values that are unprecedented for polymer nanocomposites by cross-linking the organic ligands that coat the nanocrystals (12). The unusual combination of physical properties in nanocrystal superlattices presents intriguing opportunities to use these materials as mechanically actuated optoelectronic sensors (13,14), lightweight solar sails (15), and ultrathin barriers and coatings (16,17), but warrants the development of a thorough understanding of the mechanical behavior of nanocrystal superlattices. In particular, the roles of nanocrystal packing geometry, ligand structural conformation, and ligand-ligand and ligand-nanocrystal interactions must be clarified to design multifunctional, self-assembled polymer nanocomposites with improved mechanical ...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Tolerance to structural disorder and tunable mechanical behavior in self-assembled superlattices of polymer-grafted nanocrystals

Koshy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Especially when the binary sub-components are in the interplay distance, intimate coupling between these components becomes dominant and endows the macroscopic materials with unique physical and/or chemical phenomena with superior functionalities that cannot be achieved by either of the individual sub-components. Therefore, many strategies, including 'bottom-up' wet-chemicals and 'top-down' physical-approaches, have been intensively explored to synthesize different binary materials [3][4][5][6][7]. However, the resultant binary materials are usually facing limited option of compositions and morphologies, as well as poor controlling of distributions and distances.…”

Section: A Reviving Templating Methods For Multiple Nanostructuresmentioning

confidence: 99%

A reviving templating method for multiple nanostructures

2017

Sci. China Mater.

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Binary materials, comprised by two dissimilar components in one matrix, already exist in nature from the subatomic to the universal scale with different kinds of forms (e.g., nuclei and electrons, matter and antimatter) [1]. With the progress of nanotechnology, binary materials assembled in nanoscale become an important principle to pursuit innovative functions [2]. Especially when the binary sub-components are in the interplay distance, intimate coupling between these components becomes dominant and endows the macroscopic materials with unique physical and/or chemical phenomena with superior functionalities that cannot be achieved by either of the individual sub-components. Therefore, many strategies, including 'bottom-up' wet-chemicals and 'top-down' physical-approaches, have been intensively explored to synthesize different binary materials [3][4][5][6][7]. However, the resultant binary materials are usually facing limited option of compositions and morphologies, as well as poor controlling of distributions and distances. Therefore, exploiting an effective solution to address these issues and realize the practical implementation is a significant request.Recently, Lei and colleagues at the Ilmenau University of Technology in Germany reported a concept of binary nanostructuring to tackle this long-standing challenge [8]. They ingeniously employed a unique binary-pore anodized aluminium oxide (AAO) template to successfully realize diverse binary materials on large scale. The most important key of their technique is using a selective etching process to generate the binary-pore template, which possesses not only two sets of pores (e.g., square-shaped and round-shaped pores) but also two barriers located on the opposite side of the template (Fig. 1a). These features enable the researchers to modulate each set of pore size and shape in a high degree of freedom, as well as to deposit different materials in each set of pores separately (Fig. 1b and e).From the in-situ scanning electron microscope (SEM) investigation and electric field simulation on the as-prepared template, the authors concluded that a combination of electric-field assisted dissolution and plastic oxide flow gives rise to the growth of the unique binary-pore structures (Fig. 1c). Based on this purposed mechanism, they successfully developed ternary-and quadruple-pore templates with the same selective etching process. More interestingly, the morphology of the new etched pores, like C-pores in the ternary-pore template, can be adjusted not only by the selective etching time but also by the size difference of A-pore and B-pore. Therefore, with the size difference of A-pore and B-pore decreasing, the shape of C-pores can gradually change from oval to round (Fig. 1d). Considering that their binary-pore templates are also realizable in a wide range of interpore distance from 142 ± 13 to 573 ± 27 nm, the capability of the binary-pore template is far more beyond than those of the state-of-art hard and soft templates [9].Combining with well-established approa...

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“…The forces involved in these interactions can occur at the whole-nanoparticle level (e.g., entropic forces that drive the packing of hard spheres into a dense lattice) (8,62) or in localized regions (e.g., the hybridization of complementary DNA molecules attached to particles) (52), and often these levels function cooperatively (63,64). Whereas most interactions are relatively short ranged at the nanoscale and rarely influence next-nearest neighbor interactions, many-body effects and population-level interactions become important in crystalline assemblies, given the large number of particles, and thus we focus on these effects here.…”

Section: From Nanoparticles To Colloidal Crystalsmentioning

confidence: 99%

The nature and implications of uniformity in the hierarchical organization of nanomaterials

O’Brien

Jones

Mirkin

2016

Proc. Natl. Acad. Sci. U.S.A.

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In this Perspective, we present a framework that defines how to understand and control material structure across length scales with inorganic nanoparticles. Three length scales, frequently discussed separately, are unified under the topic of hierarchical organization: atoms arranged into crystalline nanoparticles, ligands arranged on nanoparticle surfaces, and nanoparticles arranged into crystalline superlattices. Through this lens, we outline one potential pathway toward perfect colloidal matter that emphasizes the concept of uniformity. Uniformity is of both practical and functional importance, necessary to increase structural sophistication and realize the promise of nanostructured materials. Thus, we define the nature of nonuniformity at each length scale as a means to guide ongoing research efforts and highlight potential problems in the field.nanomaterial | uniformity | colloidal crystal | dispersity | hierarchy

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Structural diversity in binary superlattices self-assembled from polymer-grafted nanocrystals

Cited by 222 publications

References 71 publications

Tolerance to structural disorder and tunable mechanical behavior in self-assembled superlattices of polymer-grafted nanocrystals

Tolerance to structural disorder and tunable mechanical behavior in self-assembled superlattices of polymer-grafted nanocrystals

A reviving templating method for multiple nanostructures

The nature and implications of uniformity in the hierarchical organization of nanomaterials

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