Directed Motion of Metallic Active Colloids: Design and Applications

open_access
Open Access
Author:
Unruh, Angus
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
August 03, 2023
Committee Members:
Igor Aronson, Major Field Member
Lauren Zarzar, Major Field Member
Darrell Velegol, Outside Unit & Field Member
Ayusman Sen, Chair & Dissertation Advisor
Philip Bevilacqua, Program Head/Chair
Keywords:
colloids
nanoscience
micromotors
active matter
Abstract:
The potential applications of micro-scale active colloids, such as targeted drug delivery, small molecule sensing, environmental remediation, and directed microscale assembly typically require, or are at least would be benefitted by, precise control over the direction of particle motion. This dissertation focuses on methods for developing and implementing systems in active colloidal particles, the motion of which can be directed to a degree of accuracy. Chapter 1 introduces general applications made possible through micro-scale active particles, as well as a summary of some of the difficulties posed by micro-scale fluid dynamics and methods that are used to overcome them to produce motion. Chapter 2 deals with a system of metallic microparticles, the motion of which is dictated by their shape. This chapter discusses the process of designing and implementing the shape-directed particles, as well as modeling their behavior to predict direction of motion based on shape. Chapter 3 concerns tri-metallic microparticle disks whose motion is driven by electrophoresis, but the direction of which can be controlled via magnetic fields. These particles can be made to display a variety of complex trajectories, limited only by the complexity of the magnetic field being applied. Chapter 4 moves on slightly from directed motion and instead explores a specific application possible through active colloid particles: the catalytic degradation of nerve agent pollutants by metal-organic frameworks (MOF) enhanced by the motion of active Janus particles. This chapter discusses the design and synthesis of hybrid Janus particles consisting of a micro-sphere coated half by UiO-66 MOF and half by platinum metal, creating a motile particle capable of catalytic hydrolysis of nerve agents. Finally, Chapter 5 concludes the dissertation and briefly suggests future directions in which the previous projects could move.

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