Fabrication and Mechanical Properties of Large‐Scale Freestanding Nanoparticle Membranes

He, Jinbo; Kanjanaboos, Pongsakorn; Frazer, Laszlo; Weis, Adam; Xiao, Lin; Jaeger, Heinrich M.

doi:10.1002/smll.201000114

Cited by 144 publications

(250 citation statements)

References 29 publications

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“…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.…”

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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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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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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“…[3][4][5] Briefly, the substrate is placed on a hydrophobic surface (Teflon tape) and covered with a water droplet (see Fig. S1).…”

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confidence: 99%

Self-Assembled Nanoparticle Drumhead Resonators

Kanjanaboos¹,

Lin

Sader

et al. 2013

Nano Lett.

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Sample Preparation: Au nanoparticles were synthesized and size-selected through a digestive ripening process.1 Fe 3 O 4 nanoparticles were prepared using the synthetic procedure described by Park et al. 2 Nanoparticle monolayers were formed and deposited onto hole-containing substrates (silicon-nitride-covered silicon chips or TEM grids) using drying-mediated self-assembly, as described elsewhere. [3][4][5] Briefly, the substrate is placed on a hydrophobic surface (Teflon tape) and covered with a water droplet (see Fig. S1). Next, a droplet of nanocrystals suspended in toluene is deposited on the side of the water droplet. A compact monolayer quickly forms at the water-toluene interface. After the toluene evaporates, the substrate is placed on a mesh to aid drying. As the remaining water evaporates, the monolayer eventually touches the substrate and freestanding membranes drape themselves across the holes, slightly receding below the substrate

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“…1a-d. NP films were prepared by sequentially depositing monolayers of AuNPs using a slightly modified procedure from what we have used previously to form free-standing NP monolayers of various core materials and encapsulating ligands [20][21][22][23] (see Methods). Briefly, NP monolayers were draped one monolayer at a time onto the PC substrate, and the process repeated until a desired number of transfers were obtained.…”

Section: Resultsmentioning

confidence: 99%

“…Subsequently, B40 ml of a toluene solution containing dDT-AuNPs was added to the three-phase contact line of the water droplet. Under these conditions, the insolubility of water and the dDT-AuNP toluene solution drives the formation of NP monolayers at the air-water interface, which can then be subsequently transferred to different substrates [20][21][22][23] . Here immediately after the toluene evaporated (B10 min), the monolayer was gently draped on the PC membrane by simultaneously tilting the Petri dish and removing the water via a pipette.…”

Section: Methodsmentioning

confidence: 99%

“…Owing to the flexibility by which ligated NPs can be synthesized, including both the core materials themselves and the encapsulating ligands 43,44 , we believe the approach outlined here can be generalized to a similar set of functionalities as their SAM counterparts for different core materials. Previous work has already demonstrated that strong ligand-ligand interactions required for NP film stability are attainable not only for alkanethiol-AuNPs [20][21][22]45,46 , but other core materials such as cobalt oxide and iron oxide with oleylamine and oleic acid ligands 21 , as well as DNA-coated NPs 47 . The end result is a potentially powerful route towards engineering a set of desired interactions in which colloidal NPs are functionalized a priori with the desired functionality 48,49 .…”

Section: Article Nature Communications | Doi: 101038/ncomms6847mentioning

confidence: 99%

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Ion transport controlled by nanoparticle-functionalized membranes

et al. 2014

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From proton exchange membranes in fuel cells to ion channels in biological membranes, the well-specified control of ionic interactions in confined geometries profoundly influences the transport and selectivity of porous materials. Here we outline a versatile new approach to control a membrane's electrostatic interactions with ions by depositing ligand-coated nanoparticles around the pore entrances. Leveraging the flexibility and control by which ligated nanoparticles can be synthesized, we demonstrate how ligand terminal groups such as methyl, carboxyl and amine can be used to tune the membrane charge density and control ion transport. Further functionality, exploiting the ligands as binding sites, is demonstrated for sulfonate groups resulting in an enhancement of the membrane charge density. We then extend these results to smaller dimensions by systematically varying the underlying pore diameter. As a whole, these results outline a previously unexplored method for the nanoparticle functionalization of membranes using ligated nanoparticles to control ion transport.

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Fabrication and Mechanical Properties of Large‐Scale Freestanding Nanoparticle Membranes

Cited by 144 publications

References 29 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

Self-Assembled Nanoparticle Drumhead Resonators

Ion transport controlled by nanoparticle-functionalized membranes

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