Functional Nanocomposite Surfaces for Antibacterial, Oil–Water Separation, and Optical Applications

Abstract

Surface functionalisation can be used to modify the interaction between liquids and solid surfaces which is of importance in many applications such as self-cleaning, anti-fouling, and anti-fogging. The use of nanocomposite materials also provides a way of improving particular properties of the film even when small amounts of nano-material is used. The use of nanocomposite coatings to tailor the wettability, as well as to incorporate additional properties into surface coatings has been studied in this thesis for antibacterial, oil–water separation, and optical applications.
Chapter 1 provides an introduction to nanocomposite coatings including a brief review of how they are prepared and for what applications they are used. Chapter 2 provides information on how surface wettability is measured as well as summarising the other experimental techniques used throughout this thesis.
Chapter 3 describes the application of polymer–nanoparticle–fluorosurfactant complex nanocomposite coatings for antibacterial oil–water separation applications. Porous substrates coated with these polymer–nanoparticle–fluorosurfactant complex nanocomposite coatings are found to readily separate oil–water mixtures under both static and continuous flow as well as displaying antibacterial surface properties against Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria). A key advantage of this approach for coating substrates is its single-step simplicity. Potential applications include provision of safe drinking water, environmental pollution clean-up, and anti-fogging.
Chapter 4 utilises a single-step, low temperature, solventless atomised spray plasma deposition technique for the preparation of antibacterial polymer–metallosurfactant nanocomposite coatings which are highly active against both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria).
Chapter 5 extends the use of the atomised spray plasma deposition technique into optical applications with the preparation of high refractive index hybrid polymer and polymer–inorganic nanocomposite coatings. Refractive indices as high as 1.936 at 635 nm wavelength have been obtained for 4-bromostyrene / toluene + TiO2 layers using very low titania loadings (8% w/v). Thin films with any desired refractive index up to 1.936 can be easily deposited by varying the precursor mixture composition.