Degree

Doctor of Philosophy (PhD)

Department

Cain Department of Chemical Engineering

Document Type

Dissertation

Abstract

Colloids are suspensions of microscopic insoluble particles dispersed in a continuum phase such as liquid or gas. Colloids are found in our everyday life from food and cosmetic industries to pharmaceutical and biomedical applications. Depending on a global minimum of the free-energy landscape, colloidal suspensions can be classified as two major classes: equilibrium or active colloidal system. This Ph.D dissertation presents strategies to engineer equilibrium self-assembled structures and out-of-equilibrium active matter using various interparticle forces.

First, we introduce the means to promote the equilibrium self-assembled structures driven by adsorption of colloids at interface. Typically, adsorption of colloids at interface is governed by a complex interplay of particle-particle and particle-interface interactions. Using ecofriendly lignin nanoparticles as a model colloid, we show that adsorption of particles at liquid-liquid interface is driven by electrostatic, van der Waals, and hydrophobic interaction. Irreversibly adsorbed lignin particles at the interface can be applied as an “green” alternative to current non-biodegradable oil herders. We also present adsorption process of proteins on solid surface and mechanism of protein corona formation around a nanoparticle by studying various interparticle interactions.

For out-of-equilibrium active matter, colloidal particles in a suspension continuously consume the energy from the environment, thus they only assemble/self-propel in the presence of the energy. We use magnetic and electric fields as a tool to control the injection of the force into colloidal systems and transport the particles within medium. We show that application of magnetic field on a magnetic fluid drive the transport of particles from edge to center of a droplet which can direct surface patterning of colloids on solid surface. Lastly, we introduce that the transport and trajectory of polymeric microparticles carrying metal patches in electric field can be directed by designing patch symmetry. We show that transport ability of particles through a complex environment hinges on their trajectory. The principles and strategies presented in this dissertation offer better understandings on various colloidal interactions thus guide us to design next-generation nanomaterials.

Committee Chair

Bharti, Bhuvnesh

Available for download on Monday, March 14, 2022

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