Date of Award

8-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Committee Member

Dr. George Chumanov, Committee Chair

Committee Member

Dr. R Kenneth Marcus

Committee Member

Dr. Carlos D. Garcia

Abstract

Silver nanoparticles (AgNP) are used for many analytical and imaging techniques because they represent the most efficient mechanism by which light interacts with matter. The stability of AgNPs remains an important factor for their application. Due to their tendency to aggregate, methods for stabilizing AgNPs, mainly the addition of surfactants, have been developed. Surfactants can prevent agglomeration of AgNPs, however they can inhibit further surface modification of the particles. To overcome this problem, AgNPs were synthesized in the presence of Na2SiO3, yielding a silica shell that substantially improved the particles' stability without compromising their surface chemistry. Potential benefits are described in chapter 1. Details of this method allowing controlled thickness of a silica shell via ethanol precipitation are presented in chapter 2. These silica shells can act as a scaffold for further surface modification as well as allow the synthesis of asymmetric structures. To prove the concept of the asymmetric structure synthesis, silver dimers were synthesized by impregnating the silica shell with silver ions. Uniform dimers were made via a homogeneous solution reaction. The method is expected to find general applicability for synthesizing various oligomeric nanostructures. In chapter 4, shape change via partial dissolution of crystalline AgNPs in aqueous suspension are discussed. The dissolution of particles yielded more rounded crystals contain many small facets which are more reactivity than the large facets of the initial crystalline state. This finding opened the possibility for producing more reactive nanoparticles. That can find applications such as Surface Enhanced Raman Scattering as well as catalysis are expected to be improved upon using this more reactive crystalline form of AgNP.

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