Novel Antimicrobial Coatings

Antimicrobial coatings play an important role in stopping the spread of pathogens and diseases. This thesis is about the synthesis of novel antimicrobial coatings via wet chemical methods and plasmachemical deposition methods. Chapter 1 provides an overview of the threat posed by bacteria, and the various methods used to stop the spread of pathogens. It also briefly reviews the different types of coating systems used throughout this thesis. Chapter 2 provides a brief synopsis of the analytical and experimental techniques used in this thesis. Chapter 3 details the synthesis of a coating that combines polydopamine and cinnamaldehyde. The coating is characterised, including its antibacterial activities. The coating method is extended to tannic acid and polyethyleneimine, both of which also produce antibacterial coatings. The use of porous substrates to absorb cinnamaldehyde to produce long-lasting antibacterial surfaces is also described. Chapter 4 describes coatings that are produced by combining tea, cinnamaldehyde, and a metal salt. Both copper and silver salts are utilised. The coatings are found to have strong antibacterial efficacies, and are also found to be antiviral against murine coronavirus (mouse hepatitis virus A59), a potential surrogate for SARS-CoV-2. Chapter 5 describes how pulsed plasma polymer coatings can be combined with liquid lubricants to produce slippery surfaces. A range of different monomers and lubricants are tested, with many forming slippery surfaces that exhibit excellent water repellency. Fluorinated systems are used to produce omniphobic slippery surfaces. Use of cinnamaldehyde as a lubricant endows the slippery surfaces with strong antibacterial efficacy. Chapter 6 details how pulsed plasma coatings may be used to prevent (or encourage) fouling of microalgae on surfaces. Hydrophilic coatings produce the best anti-biofouling results, and are non-toxic towards the microalgae species tested.