UNIFORM AND NANOPATTERNED FILMS FROM Cr8F8PIV16 AS A ROUTE TO MODIFY SURFACES

Abstract

The thesis aims to elucidate the potential of uniform and nanopatterned films derived from a novel metal-organic molecule Cr8F8Piv16 [Cr8F8(O2CtBu)16] as a route to modify surfaces. The outcomes of this investigation are arranged into two segments. The first segment focuses on the identification and optimisation of more scalable techniques to produce uniform and nanopatterned films (single or multi-layer) as well as their characterisation. The second segment elucidates the wetting and corrosion performance of these films. In terms of the film production techniques, thermal sublimation and UVC curing (Ultraviolet radiation, wavelength: 254 nm) have been established and optimised as reliable methodologies for uniform and patterned films of up to 750 nm thick on silicon and polished carbon and stainless steel. The characterisation of the films indicates that the films are extremely smooth and non-porous. In addition, a multi-layer approach of thinner (e.g. 300 nm) films exhibit an overall better quality than single-layer thick films (e.g. 1 um). A wetting study of the patterned films was performed using static contact angles. A simple/crude patterning technique with only multi-micron pitch patterns (365, 165, 65 um) was selected with the hope that it will facilitate the scalability of this technology. We demonstrate that patterned films can substantially increase the hydrophobicity of both silicon and steel substrates and of uniform films of the same material. The double-layer films with parallel-line patterns approach super-hydrophobicity in the direction parallel to the lines. Finally, we demonstrate that it is possible to repeat the double-layer patterned films on polished SS304 and they exhibit similarly increased hydrophobicity. The use of about 500 nm thin films as primary coating corrosion protection of polished CS1010 and SS304 was investigated. The films exhibit an impedance of two to three magnitudes greater than bare steel in NaCl and CO2 solutions at 20 deg. C. However, the impedance gradually decreases with time, a fact which was attributed primarily to the insufficient thickness and improper coverage of the polished steel. In addition, films prepared under the experimental conditions of this study are prone to fracture in heated solutions at 45-60 deg. C irrespective of corrosion, likely due to thermal effects. The latter may be potentially mitigated with further optimisation of UV curing as it was observed to affect the film hardness and elasticity.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Richard Winpenny (Supervisor) & Scott Lewis (Supervisor)