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Facile Fabrication of Functional Membranes through Oxidant-Triggered Plant-Inspired Surface Modification
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- Author / Creator
- Chen, Yulan
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Surface functionalization methods are critically important for materials research community in endowing surfaces with multiple novel and unique properties. Plant-derived polyphenolic compounds exhibit material-independent adhesive affinity and form versatile coatings via synchronous oxidation and self-polymerization in weak alkaline solutions. However, several drawbacks like low homogeneity and time-consuming chemical reactions hinder their practical implementations. A simple and effective surface modification approach based on catechol (CA) by using sodium periodate (SP) as a trigger has been studied in this work to address these concerns. With our strategy, SP-mediated CA films with good uniformity were successfully deposited on various dense and porous substrates in a relatively short time. The polymerization and deposition kinetics of CA under chemical oxidation were identified by UV–vis spectroscopy, atomic force microscopy (AFM), and ellipsometry. The systematic investigation of membrane chemical, wetting, and permeation properties under different coating times demonstrated that the optimal coating time was 2 h.
In water purification, the optimally modified PVDF membranes, showing superhydrophilicity and underwater superoleophobicity, possess outstanding pure water permeability, high adsorption capacity for copper ions, and excellent rejection to oil.
In part II, our modification method was employed to fabricate a hydrophilic-hydrophobic Janus membrane that can be applied in the generation of hollow polymeric capsules. The asymmetric structure of Janus membrane was verified through characterization techniques including X-ray spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and contact angle measurements. To provide proof-of-concept of Janus membrane emulsification, a homemade apparatus was used to make double emulsions (i.e., gas-in-oil-in-water emulsions). The experimental parameters (e.g., gas flow rate, pH of continuous phase, and surfactant concentration) controlling the drop size and size distribution were studied comprehensively. The generated double emulsions underwent polymerization upon exposure to UV light, thus producing UV-cured hollow polymeric microspheres.
In addition to reporting a simple and versatile strategy for surface modification and its applications in membrane technology, this dissertation paves a way to illuminate the process of plant phenolic deposition and also provides a feasible method to produce massive double emulsions through membrane emulsification. -
- Graduation date
- Fall 2019
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- 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.