title: Nanoparticle layer deposition for highly controlled multilayer formation based on high- coverage monolayers of nanoparticles.
abstract: This paper establishes a strategy for chemical deposition of functionalized nanoparticles onto solid substrates in a layer-by-layer process based on self-limiting surface chemical reactions leading tocompletemonolayer formation within the multilayer system without any additional intermediate layers - nanoparticle layer deposition (NPLD). This approach is fundamentally different from previously established traditional layer-by-layer deposition techniques and is conceptually more similar to well-known atomic and molecular - layer deposition processes. The NPLD approach uses efficient chemical functionalization of the solid substrate material and complementary functionalization of nanoparticles to produce a nearly100% coverageof these nanoparticles with the use of "click chemistry". Following this initial deposition, a secondcomplete monolayerof nanoparticles is deposited using a copper-catalyzed "click reaction" with the azide-terminated silica nanoparticles of a different size. This layer-by-layer growth is demonstrated to produce stable covalently-bound multilayers of nearly perfect structure over macroscopic solid substrates. The formation of stable covalent bonds is confirmed spectroscopically and the stability of the multilayers produced is tested by sonication in a variety of common solvents. The 1-, 2- and 3-layer structures are interrogated by electron microscopy and atomic force microscopy and the thickness of the multilayers formed is fully consistent with that expected for highly efficient monolayer formation with each cycle of growth. This approach can be extended to include a variety of materials deposited in a predesigned sequence on different substrates with a highly conformal filling.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
authors.forename: Mackenzie G
authors.initials: MG
authors.lastname: Williams
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Miller
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
authors.forename: Andrew V
authors.initials: AV
authors.lastname: Teplyakov
keywords: SEM; monolayer formation; nanoparticle surface functionalization; “click chemistry”