Keywords

Silicon nanoparticles, Hydrosilylation, Gold nanoparticles, Catalysis, Plasmonics, Self-assembly

Abstract

Surface modification of colloidal nanoparticles is essential for broadening the scope of nanotechnology. In this dissertation, we discuss novel approaches to functionalize the surface of nanoparticles to tailor their properties for applications including radical polymerization inhibitors, supported heterogeneous catalysts, and building blocks for plasmonic devices. First, we investigate the interaction of hydrogen-terminated silicon nanoparticles (H-SiNPs) with Karstedt's catalyst and report a room‑temperature synthesis of Pt-coated SiNPs with highly tunable Pt loading. Analysis of the Pt on-Si ensemble reveals surface-bound Pt(II) on SiNPs which can undergo ligand exchange. Upon calcination, Pt-loaded SiNPs catalyze the hydrogenation of phenyl acetylene, and the SiNP scaffold enables efficient recovery and reuse of the catalyst. Conditions that favor the reductive elimination of the catalyst and efficient hydrosilylation of olefins are also discussed. Next, we report H-SiNPs as inhibitors for anerobic thermal autopolymerization of methacrylates. Prior to use, these solid-state inhibitors can be easily removed from the methacrylic monomers by low-speed centrifugation, offering great advantage to the traditionally used phenols and quinones. Analysis of SiNPs isolated after heating in methacrylates reveals the grafting of ester groups. As such, thermal hydrosilylation is presented as a powerful yet facile route to attach ester and allyl ester groups onto the surface of SiNPs. Finally, we report a method to rapidly and uniformly assemble gold nanoparticles (AuNPs) and their clusters on cm‑scale unmodified substrates. Cetyltrimethylammonium (CTAC) capped AuNPs were conjugated to a sparse coating of poly(ethylene glycol) and extracted into dichloromethane. The clustered patterns were deposited on hydroxyl terminated surfaces from stable dispersions using centrifugal force. The degree of clustering on substrates was tuned by varying a single parameter, the concentration of CTAC in the deposition dispersion. This approach bridges the gap between methods for depositing isolated AuNPs (typically using electrostatic interactions) and AuNP clusters (using covalent or electrostatic binders) and enables large-scale uniform deposition of isolated AuNPs, as well as clusters with tunable size. The non‑covalent assembly onto the substrate provided a means for depositing AuNPs into nanowells in topographically patterned substrates: after uniform deposition onto these substrates, the AuNPs on the surface were selectively removed using mechanical rubbing. This facile approach enabled large-scale selective deposition of AuNPs into patterned substrates that are attractive as SERS substrates and refractive index sensors.

Completion Date

2023

Semester

Fall

Committee Chair

Kuebler, Stephen

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Chemistry

Degree Program

Chemistry

Format

application/pdf

Identifier

DP0028451

Language

English

Release Date

June 2024

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

Campus Location

Orlando (Main) Campus

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