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superhydrophobic, contact angle, photolithography, superoleophobic

Koch, Brendan M

Supervisor and department: Elliott, Janet Chemical Engineering Amirfazli, Alidad Mechanical Engineering

Examining committee member and department: Chung, Hyun-Joong Chemical Engineering

Department: Department of Mechanical Engineering

Specialization:

Date accepted: 2014-09-29T13:28:30Z

Graduation date: 2014-11

Degree: Master of Science

Degree level: Master's

Abstract: This thesis features experimental work done to fabricate and characterize silicon surfaces patterned using photolithographic techniques, both standard and novel, to produce a variety of surfaces with roughness of controlled geometric properties. In specific, one set of the surfaces fabricated had pillars with vertical sidewalls to explore the effects of feature size on contact angle, and another set of surfaces had pillars with undercut geometry to test for superoleophobicity. Contact angles were measured on these surfaces using three different test fluids: water, ethylene glycol, and hexadecane. This allowed for a broad range of surface tensions to be examined and thus for a variety of behaviors to be observed during characterization. In analyzing the data new complexities already seen in the literature but not fully explored became apparent. In order to understand these complexities a new framework was developed to empirically describe how liquids behave on rough surfaces such as the ones that were fabricated. This new framework has provided considerable insight and has greatly improved understanding of the behavior of contact angles on the fabricated surfaces and other surfaces in the literature. The framework has allowed us to better understand how drops on textured surfaces behave and how measurements relate to various methods of understanding contact angles, such as the Cassie and Wenzel equations. This is particularly important when assessing surfaces with novel texturing features such as the overhanging cap structure and comparing their behaviors with that of surfaces better characterized in the literature such as surfaces with vertical sidewall pillars, and being able to more accurately and precisely determine what the strengths and weaknesses of these new surfaces really are.

Language: English

DOI: doi:10.7939-R3VT1GZ2K

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Autor: Koch, Brendan M

Fuente: https://era.library.ualberta.ca/


Introducción



Fabrication and Characterization of Photolithographically Patterned Rough Surfaces Demonstrating Extreme Contact Angle Behavior by Brendan Koch A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Mechanical Engineering University of Alberta © Brendan Koch, 2014 Abstract This thesis features experimental work done to fabricate and characterize silicon surfaces patterned using photolithographic techniques, both standard and novel, to produce a variety of surfaces with roughness of controlled geometric properties.
In specific, one set of the surfaces fabricated had pillars with vertical sidewalls to explore the effects of feature size on contact angle, and another set of surfaces had pillars with undercut geometry to test for superoleophobicity.
Contact angles were measured on these surfaces using three different test fluids: water, ethylene glycol, and hexadecane.
This allowed for a broad range of surface tensions to be examined and thus for a variety of behaviors to be observed during characterization.
In analyzing the data new complexities already seen in the literature but not fully explored became apparent.
In order to understand these complexities a new framework was developed to empirically describe how liquids behave on rough surfaces such as the ones that were fabricated. This new framework has provided considerable insight and has greatly improved understanding of the behavior of contact angles on the fabricated surfaces and other surfaces in the literature.
The framework has allowed us to better understand how drops on textured surfaces behave and how measurements relate to various methods of understanding contact angles, such as the Cassie and Wenzel equations.
This is particularly important when assessing surfaces with novel texturing features such as the overhanging cap structure and comparing their behaviors with that of surfaces better characterized in the literature such as surfaces wit...





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