Date of Award

2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering

Department

Chemical Engineering

First Advisor

Arijit Bose

Abstract

Nanoscale materials often exhibit fascinating physical, chemical, and biological properties which are considerably different from those of their macro-and/or microscale counterparts. These unique characteristics have led to considerable growth over the last decade in nanomaterial-enabled applications in areas such as biomedicine, environmental sensing and remediation, and energy production and storage. In this dissertation, techniques are presented to create new nanomaterials relevant to these areas.

Gold nanostructures are an example of a nanomaterial with great interest in biomedical therapy and sensing applications due to their high chemical and physical stability, ease of synthesis and surface functionalization and their unique optical properties. High photothermal heat generation efficiency and their biocompatibility have made them an effective tool for thermal destruction of cancer cells. Magnified electromagnetic field on their surfaces allows gold nanostructures to be used as ultrasensitive nano-sensors for analyte detection using surface-enhanced Raman scattering (SERS). There remains significant interest in further improving the synthesis and design of gold nanostructures to maximize their potential applications. In biomedicine, for instance, the absorbance spectra of gold nanostructures need to be stable and tuned to the near-infrared (NIR) window (650–1350 nm) where biological tissues have minimal light absorption, while yet it is also desirable for the nanostructures to degrade to avoid accumulation in the body after treatment. Likewise in SERS applications, it is important that the nanostructures are stable and resist surface fouling, while yet analytes with low affinity for the metal surface must be enriched at the surface to overcome poor detection limits.

A versatile templating strategy was developed to create gold nanoshells on different dielectric cores for photothermal heating and sensing applications. The strategy allows for tunable NIR absorbance and high degradation capabilities upon laser irradiation using soft templates. When carbon nanomaterials are used as the template, the carbon improves the affinity of different analytes to the surface of the hybrid nanostructures, yielding sensitive SERS-active materials for monitoring aqueous pollutants.

In the area of environmental remediation, nanoparticles with mixed wettability properties have been recently explored as alternative oil spill dispersants to help avoid the negative effects of surfactants on marine species. Adequate dispersing qualities and low toxicity are generally considered as the criteria for a good oil dispersant. However, their impact on the oil biodegradation process is still poorly understood. The attachment of bacteria to the oil/water interface, as the first step in oil biodegradation, was investigated to study the potential inhibitory effect of two commercially available dispersants, Corexit-9500 and Tween 20, and also carboxyl-terminated carbon black nanoparticles on biodegradation process.

Finally, conductive nanoparticles were used to enhance the electrical conductivity of polymer nanocomposites. While graphene, with a high aspect ratio and excellent conductivity, seems a promising filler to induce conductivity into a polymer, dispersing it uniformly within a polymer network remains a challenge due to their strong attractive forces. To assist dispersion, carbon black nanoparticles were used as a secondary filler to prevent restacking the graphene sheets within the polymer matrix. As a result, the electrical conductivity of the composite was significantly increased and sustained even at high nanoparticle loading.

Available for download on Sunday, April 19, 2020

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