Chemical and physical properties of organic coatings as barriers against the transport of moisture and ions

Corrosion in organic-coated metals presents a complex and costly
challenge to manage due to the intricate interplay of subsystems within a
coated metal exposed to a corrosive environment. In response, organic
coatings have evolved in such a way that they can provide protection for
several decades. However, the performance gain is at the cost of
increasing innovation times and challenging analytical characterisations
since the time scales of failure dynamics have become very slow. To
shorten the innovation cycles, mechanistic models to predict the failure
of organic coatings are a necessity and in-line with increasing demands
for sustainability and environmentally friendly approaches in the chemical
industry.
As part of a large-scale project known as PredictCor, this thesis aimed
to establish a knowledge platform for water and ion transport through
model organic layers, the availability of which could lay the groundwork
towards synthesising a predictive model. First, a series of
methodologies were developed for in-house quantification of crucial
transport properties of polymer films, which are solubility,
diffusivity, and permeability, to differentiate a large number of
model systems. Next, the impact of the formulation components of
UV-cured model systems was studied with a large set of analytical
characterisation tools to provide a holistic view of the performance of the
polymer layer as a barrier in coating applications. The complexity of the
formulations was increased towards the end of the thesis. Finally, the
well-characterized model systems were benchmarked against standard
anti-corrosion coatings systems prepared by the industry.
The results obtained in this thesis contributed to developing
new methodologies for measuring transport properties, critical evaluation
of water diffusivity calculations, and establishing UV-cured acrylates as
potential model coatings for the creation and validation of an
industrially relevant predictive model for the onset of corrosion. The
outcome of the work also offers insights into some future research
directions, including chemical analysis of nanoscale non-uniformities
in UV-cured acrylates and engineering interstitial zones in these
layers for improved barrier properties. The comprehensive approach of the
work provides a broader understanding of transport phenomena in UV-
cured layers, making it a contribution to other applications as well as
corrosion in coated metals.