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Controlling Gold Nanoparticle Assembly through Particle-Particle and Particle-Surface Interactions

Kelley, John Joseph
http://orcid.org/0000-0003-4323-7676
http://rave.ohiolink.edu/etdc/view?acc_num=dayton1533083850424849

Abstract Details

2018, Doctor of Philosophy (Ph.D.), University of Dayton, Materials Engineering.
Two-dimensional assemblies of colloidal gold nanoparticles were deposited via electrostatic self-assembly onto silicon substrates modified with aminopropyltriethoxysilane. Assemblies were tuned by systematically adjusting the pH and ionic strength of the nanoparticle solutions and the fraction of adsorbed aminosilane molecules on the silicon surfaces. The nanoparticles were characterized by their size distribution, solution stability and electrokinetic properties. The resulting two-dimensional assemblies varied in particle surface coverage, interparticle separation and lateral organization. Increasing solution pH intensified interparticle repulsions and reduced the charge density of the aminosilane substrate, thus decreasing the fractional monolayer coverage of particles. Additionally, increasing ionic strength reduced interparticle separations, which were described by radial distribution functions, and consequently produced denser particle assemblies. At long adsorption times, surface coverage approaches a maximum which was constrained by the extent of interparticle repulsion and particle-surface interactions. With strong surface attraction of the pure aminosilane surface, the particles were incapable of lateral rearrangement during the adsorption process and, at best, organized into liquid-like structures, in agreement with the random sequential adsorption model for colloidal monolayers. In an effort to circumvent this issue, non-binding alkylsilanes were incorporated into the modified surfaces, thereby reducing the aminosilane surface density and weakening the attractive potential of the surface. These mixed silane surfaces were characterized to reveal their chemical and interfacial energetic properties. At a particular threshold of reduced aminosilane density, nanoparticle coverage fell considerably and two-dimensional order degraded. The local geometries of particle assemblies were evaluated by Voronoi tessellation which provided indication of structural transformations with changing solution and surface conditions. As a result, optimal processing parameters were described for obtaining monolayers of gold nanoparticles with varying degrees of surface coverage and two-dimensional arrangement. The results from this study expands the understanding of the underlying chemical and physical mechanisms behind colloidal stability and particle adsorption. This progresses towards the realization of arrays of highly-ordered and densely packed nanoparticles of diverse chemistries largely assembled in parallel onto assorted surfaces using minimal processing.
Erick Vasquez, PhD (Committee Chair)
Richard Vaia, PhD (Advisor)
Andrey Voevodin, PhD (Committee Member)
Paul Murray, PhD (Committee Member)
Donald Klosterman, PhD (Committee Member)
199 p.
Materials Science
gold nanoparticle; electrostatic self-assembly; self-assembled monolayer; amino silane; mixed silane; random sequential adsorption; radial distribution function; Voronoi tessellation

Recommended Citations

Citations

  • Kelley, J. J. (2018). Controlling Gold Nanoparticle Assembly through Particle-Particle and Particle-Surface Interactions [Doctoral dissertation, University of Dayton]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1533083850424849

    APA Style (7th edition)

  • Kelley, John. Controlling Gold Nanoparticle Assembly through Particle-Particle and Particle-Surface Interactions. 2018. University of Dayton, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=dayton1533083850424849.

    MLA Style (8th edition)

  • Kelley, John. "Controlling Gold Nanoparticle Assembly through Particle-Particle and Particle-Surface Interactions." Doctoral dissertation, University of Dayton, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1533083850424849

    Chicago Manual of Style (17th edition)

dayton1533083850424849
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This open access ETD is published by University of Dayton and OhioLINK.