Atomised Spray Plasma Deposition of Functional Polymer Coatings

Atomised spray plasma deposition (ASPD) is a technique used to functionalise surfaces. The atomisation of precursor into electrical discharges allows the deposition of: (i) non-polymerisable precursors, which cannot be deposited through conventional surface functionalisation methods; (ii) viscous or lowvapour-pressure precursors, which cannot be deposited in conventional gasphase plasma polymerisation; (iii) precursor–nanoparticle slurry. In this thesis, atomised spray plasma deposition was employed to fabricate functional polymer coatings for diverse applications such as liquid repellent, wet electrical, and antibacterial coatings. Liquid-repellent surfaces were fabricated by the deposition of a mixture of nanoparticles and a perfluorinated precursor forming a highly crosslinked polymer matrix containing the nanoparticles. The wettability of the ASPD nanocomposite coatings resulted in water contact angle values of ~170°; the nanoparticles, acting as nanofillers, enhanced the mechanical properties of the ASPD polymer coatings. Fluorine-free and low-vapour-pressure precursor was used to fabricate hydrophobic ASPD polymer coatings and the effect of the in situ plasma posttreatment of ASPD poly (isodecyl acrylate) coatings was tested. The effect of the plasma post-treatment enhanced the crosslinking degree, mechanical and adhesion properties as well as the enhancement of the wet electrical barrier of the ASPD poly (isodecyl acrylate) coatings preventing the electrical breakdown of microcircuit boards in contact with water for an applied electric field of 10 V mm−1. Further enhanced liquid repellency, mechanical properties, and wet electrical barrier to at higher applied electric field (75 V mm−1) were found for plasma post-treated ASPD 20% w/v (1H,1H,2H,2H-perfluorododecyl acrylate–perfluorotributylamine) coatings. Finally, bis-dodecylamine copper dichloride (CuDDA) metallosurfactant was employed to fabricate antibacterial-agent-release 2% w/v ASPD (CuDDA–isodecyl acrylate) coatings. It is likely that the metallosurfactant remained trapped within the plasma polymer coating through electrostatic interactions because there was a reduction of the antibacterial activity of the antibacterial polymer coating as it leached out. These antibacterial polymer coating displayed highly antibacterial activity efficiency against Gram negative E. coli and Gram-positive S. aureus bacteria. The maximum antibacterial efficiency (>99.999%) was found at 10 min of interaction time tested on both bacteria individually on the antibacterial ASPD polymer coating, which is attributed to the synergetic effect of the long hydrophobic alkyl chain and the complexation of the surfactant with Cu2+ ions.