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Tao, Li

University of British Columbia

The outbreak of COVID-19 has led to significant demand for Personal Protective Equipment (PPE), such as masks and face shields. While these PPEs can protect people from many infectious agents, they usually are one-time use and non-degradable after disposal, causing a shortage of supply and environmental issues. While many reusable substitutes, such as reusable cloth masks, were developed, their prevention capability might be compromised after prolonged usage. As such, self-disinfecting coatings have been applied to PPEs to improve antibacterial and antiviral properties. However, commercial coating methods, such as spraying and physical vapor deposition, have several limitations for PPE applications, including poor coverage, loose adhesion, and high coating temperature. This thesis work adopted an advanced atomic layer deposition (ALD) technique to fabricate nanoscale self-disinfecting coatings that overcome the above mentioned coating approaches limitations. This work investigated the ALD fabrication, material characterizations, and antimicrobial performance of titanium oxide (TiO₂) and zinc oxide (ZnO), two typical UV-activated self-disinfecting materials. The ALD-deposited TiO₂ and ZnO thin films on the glass substrate had thickness of 81.6 ± 6.6 nm and 312.8 ± 41.3 nm, respectively. Structural analysis by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron microscopy confirmed the successful deposition of TiO₂ and ZnO, most of which were amorphous. The antimicrobial properties of the ALD-TiO₂ and ZnO were evaluated against E. coli, under modified AATCC-100 standard, with commercial TiO₂ and ZnO powders as references. Data indicated that ALD-ZnO could eliminate E. coli during a 12-hour test. All the data were verified through P value test with alpha set to 0.05, and statistically proved the antimicrobial performance of the ALD-ZnO. Moreover, the nanoscale ALD-ZnO exhibited antimicrobial properties similar to commercial ZnO. On the other hand, P-value tests indicated ALD-TiO₂ coating and commercial TiO₂ powders did not generate statistically significant data that suggests antimicrobial activity toward E. coli. The different antimicrobial properties of ALD-ZnO and TiO₂ could be caused by more substantial UV absorption capability of the former than the latter, as revealed by the UV absorption test. It is expected that this work could stimulate the application of the ALD technique for applying self-disinfecting ZnO coatings for PPE.

Text

2023-01-10

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83620

Mechanical Engineering

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/