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Permanent link (DOI): https://doi.org/10.7939/R3VT1GZ2K

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Fabrication and Characterization of Photolithographically Patterned Rough Surfaces Demonstrating Extreme Contact Angle Behavior Open Access

Descriptions

Other title
Subject/Keyword
superhydrophobic
contact angle
photolithography
superoleophobic
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
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.
Citation for previous publication
Chapter 2 of this thesis, with minor modifications has been accepted for publication in the Journal of Physical Chemistry C, as B. M. L. Koch, A. Amirfazli, J.A.W. Elliott, “Modeling and Measurement of Contact Angle Hysteresis on Textured High-Contact-Angle Surfaces” In Press 2014Chapter 3 of this thesis, with minor modifications, has been accepted for publication to the Journal of Physical Chemistry C, as B. M. L. Koch, A. Amirfazli, J.A.W. Elliott, “Wetting of Rough Surfaces by a Low Surface Tension Liquid”Chapter 4 of this thesis, with minor modifications, has been submitted for publication to Langmuir as B. M. L. Koch, A. Amirfazli, J.A.W. Elliott, “Study of Model Superoleophobic Surfaces Fabricated with a Modified Bosch Etch Method”.

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