Abstract
Composites and hybrid materials are new material
combinations which can provide added value for existing
products or create novel multifunctional properties. This
thesis aimed at fabricating and modifying thin-film
composites (TFC) by using various coating technologies.
Moreover, the target was to tailor the permeability or to
create anti-fouling performance. Inorganic,
inorganic-organic and organic coating layers were made by
atmospheric plasma deposition (APD), sol-gel (SG),
atomic-layer-deposition (ALD) or polyvinyl alcohol (PVA)
dispersion coating methods. Coatings were deposited using
either roll-to-roll or batch process. APD method was used
to create an inorganic silicon oxide (SiOx) coating layer
on a low-density polyethylene (LDPE) coated board. In
addition, atmospheric plasma was used for pre-treatment
of LPDE surface prior SG coatings. The SiOx coatings did
not show a significant improvement in barrier performance
using the specific roll-to-roll process. Therefore, SG
coating method was studied instead in order to form a
barrier layer on LDPE-board by using the roll-to-roll
process. SG coatings reduced the surface roughness and
made the polymer surfaces either hydrophilic or
hydrophobic. In addition, the coating chemistry had an
effect on the oxygen and grease barrier performances. The
highly cross-linked SG coating gave a better oxygen
barrier performance, while the other SG coating revealed
an enhancement in the grease barrier. Plasma activation
of the LDPE surface enhanced the wettability and adhesion
of both SG coatings. In addition, SG coating was applied
on a polylactic acid (PLA) coated board. The SG coating
created favourable, smooth and hydrophilic primer layer
on PLA-board, which was further coated with an inorganic
aluminium oxide (Al2O3) skin layer by using ALD. The
particular TFC structure based on ALD and SG coatings
gave a slightly better barrier performance compared to a
plain ALD coating. PVA and ALD based antifouling coatings
increased the hydrophilicity and surface polarity of the
polyamide (PA) TFC membranes. All the coated membranes
indicated an enhancement in bacteria-repellence. Indeed,
the improvement in the bacterial anti-adhesion
performance of coated membranes was due to an increase in
surface polarity. The biocide-modified PVA coatings
enhanced further the anti-fouling performance due to
their antimicrobial activity. As expected, in comparison
to the uncoated membrane, the PVA-coated membranes tend
to increase the salt rejection and to reduce the water
and salt permeability. However, the biocide-modified PVA
coatings decreased the water permeability and showed also
a minor decline on the salt rejection. The ALD coatings
increased the water and salt permeability and
furthermore, reduced the salt rejection.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 31 Oct 2014 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 978-951-38-8163-4 |
Electronic ISBNs | 978-951-38-8164-1 |
Publication status | Published - 2014 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- Thin-film composite
- hybrid
- permeability
- anti-fouling