'Thin films & coatings' Roadmap - Nano Mahidol

2.5.3 Final conclusions and recommendations
Main technical barriers
Thin films and coatings have been applied in many industries over the last decades;
however, nanotechnology is now providing the tools for much more precise
characterisation and, for some types of coating, production. Most coating processes
are intrinsically difficult to control (spray coating, PVD, spin coating etc.) and if really
precise control is needed there are probably limits to what can be obtained with
these techniques. The most precise control achievable will be through self-assembly,
which intrinsically starts at the molecular level. Expanding the range of materials that
can be brought in to self-assembled layers may allow the replacement of less-precise
processes in some applications.
An important challenge is to better understand the adhesion mechanisms between
the substrate and the coating as well as between multi-layers. This has a crucial
impact on all thin films’ properties and is especially relevant for new materials being
explored. Improved computer modelling is, in the long-term, the most powerful tool
for achieving this, along with the basic theoretical understanding that would feed it.
Many of the experts have highlighted this as critical.
The possibility of coating complex 3D geometries would also broaden the range of
thin films applications. It is difficult to see how to overcome this barrier with certain
processes but, again, self-assembly techniques are much better adapted to coating
3D structures and extending the capabilities of this approach might allow the
replacement of the more problematic processes. Many of the technologies included
in this roadmap do also have serious limitations with regard to the size of the part to
be coated.
Other barriers
The broad possibilities for thin films applications could also have a counterproductive
effect. Experts in specific processes are not experts in all the markets this process
could be applied to. The lack of understanding of industrial requirements is
considered a bottleneck for all materials being researched. This is especially relevant
because thin films are part of material systems and should be integrated into other
(most of the times existent) production processes. For capital-intensive industries,
this may block new technologies deployment within the next 5 to 10 years.
Price and barriers related to production volumes have been highlighted by many
experts for many production processes and are a crucial issue to be addressed.
Experts also highlighted the lack of young researchers, the limited interest from
industry (especially in the case of silicates) or dissemination of state-of-the-art
functional nanocoatings to end-users (e.g. for polymers). Also, some environmental
issues (as found in other nanomaterial areas) have yet to be overcome in order to
allow industrial scale application in a sustainable way.
An area that has not been highlighted by the experts is metrology. If thin films are to
be massively applied, there’s the need for quick characterisation and online quality
control; otherwise, suppliers and customers won’t be able to guarantee the quality
(i.e. performance) of their nanotechnology-based products.
41 Roadmap report on
Thin films and coatings