SBO project NAPROM
Challenges for self-healing
coatings on metals
VUB – UGent – UA – Flamac
Herman Terryn
Research Group Electrochemical and Surface Engineering
Departement Materials and Chemistry
Vrije Universiteit Brussel
Introduction – NAPROM Multiple action corrosion protection
1. Self-healing coating
2. Encapsulated corrosion inhibitors
3. Leaching out of corrosion inhibitors
4. Defect closure by self-healing of polymer
Metal
Metal
Coating
Metal
Metal
Metal
Inhibitor expertise support at SURF
(support TU-Delft )
Self-healing polymer and supramolecular design and synthesis by PCR, UGent (F. Du Prez) and SC, UGent (R. Hoogenboom)
Coating morphology, chemical and interface analysis by SURF, VUB (H. Terryn, I. De Graeve)
Bulk and coating thermomechanical analysis by FYSC, VUB (B. Van Mele, G. Van Assche)
Electron microscopy support for coating analysis by EMAT, UA (S. Van Tendeloo, A. Abakumov)
Inhibitor mechanism by SURF, VUB
Polymer self-healing mechanism by SURF, VUB and FYSC, VUB }
Co-operative active
protection property
analysis by SURF and
FYSC
50 nm -5 µm
1 µm ?
metal
Consortium in NAPROM
Accelerated screening method for active corrosion
protection by SURF, VUB (A. Hubin) and Flamac (J. Paul)
Self-healing Coating
Polyester- urethane acrylate coating
=
“Shape Recovery” Polymer
Nano phase separated high Tg polymer (dark zones)
and polyester segments (light zones)
combining extreme toughness with the ability to
recover from mechanical damage by heating
Semi-crystalline PCL=Polycaprolactone soft phases, Tg 50-60 °C
Self-healing polymer
Fresh coating 2 scratches Healed coating
Stepwise healing Closed defect Major defect
Self-Healing - SEM
>50°C
<1min
Metal
Impedance Spectroscopy
Coating with Flexible Spacers
Virgin coating
Coating healed for the
second time
Healed coating
Coating scratched again
after healing
Scratched coating
SVET Analysis of Self-Healing
In 0,05M NaCl Before healing After healing
Metal
Spectroscopic techniques such as EDX and EELS provide elemental information, making the localization of elements available, furthering the understanding of the sample. The steel polymer interface. EELS elemental mapping reveals the location of the various components: the polymer (indicated by the carbon signal) fills up a indentation in the oxidized zinc surface.
Interface SH coating-galvanised steel
Inhibitor MERCAPTO-BENZOTHIAZOL
Encapsulation
Layered Double Hydroxides (LDH) Porous nanocapsules
10µm
SEM EDX
SEM
TEM
+MBT
40 nm
Leaching out
Surface Enhanced Raman Spectroscopy
LDH+MBT on AgProbe
SiNC+MBT on AgProbe
Blank AgProbe
H. Verbruggen,
K. Baerts
Metal
NSH-coating without inhibitors
High currents after 4 hr of immersion
In-situ SVET mapping above two micro-drill defects
NSH-coating with LDH + MBT
In-situ SVET mapping above two micro-drill defects
No corrosion detectable after 4 hr of immersion
Metal
Scale bar: 10 µm
Very Thin Shells
< 5µm
Scale bar 100 µm
Robust microcapsules
Protective
barrier
1st generation of Melamine
Formaldehyde (MF) capsules
plasticizer ~ 90% plasticizer content
MF
outer
shell
Accelerated screening of aging
phenomena of coatings (Flamac)
• Methods for determining aging properties and associated methods for
accelerated testing of aging phenomena in the field of the high throughput
development of coatings (Flamac)
• Early stage detection of coating defects
• Current status: o High-throughput accelerated ageing platform evaluated
Application of micro- and macro-
scratches Methodology developed for applying controlled
micro-scratch (cfr. ICON project SHREC WP 5)
– Micro-scratches1:
– order of magnitude:
– 10 μm wide, 5 μm deep
1Visualised with microscope of nano-indentor
Methodology to investigate the corrosion protection
given by a coating
Metals
Coating for
additional
protection
Developing new coatings:
Different formulations
Many conditions
FAST AND
RELIABLE
EVALUATION
METHOD
Corrosion rate
monitor device for
ranking
+
Impedance to
understand damage
mechanism
ZENSOR
+
ORP-EIS
ORP-EIS ZENSOR
• Corrosion ranking
• 2 electrode based device:
evaluate corrosion activity
• Possibility of in-situ
monitoring
• User friendly
• Simplified setup but
robust!
• Save time
• Trough
modelling
able to
understand
damage
mechanism
Signal:
Sum of all single
sines
Bode plot with info over noise levels
Supramolecular self-healing materials –
concept and design
Design:
Poster: A new class of supramolecular
thermoplastic elastomers for self-healing coatings
Lenny Voorhaar & Maria Mercedes Diaz
+ +
+ +
+ +
+ +
- -
- -
- -
- - mixing
Association of
charged end
blocks
Network crosslinked by
supramolecular interactions
Phase separated structure
Charged phase
high Tg
Uncharged
phase low Tg
Charged ABA-type triblock copolymers
Charged CBC-type triblock copolymers
Synthesis performed in UGent SC
+ +
+ +
+ +
+ +
- -
- -
- -
- -
Supramolecular self-healing materials –
thermal characterization
0.4
0.6
0.8
1
1.2
1.4
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1.8
-90 -60 -30 0 30 60 90
He
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-1
T / C
0.4
0.6
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T / C
0.4
0.6
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1
1.2
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T / C
Tg generated by the
association of
charged end blocks!
Tg 28°C
Supramolecular self-healing materials –
thermal characterization
The two Tg’s indicate phase separated
structure
DMA heating ramp shows the mechanical
properties of the supramolecular network.
Transitions the material undergoes are seen
by the drop in E’.
The supramolecular interactions keep the
material from flowing even at 80°C.
Poster: A new class of supramolecular
thermoplastic elastomers for self-healing coatings
Lenny Voorhaar & Maria Mercedes Diaz
0.4
0.6
0.8
1
1.2
1.4
1.6
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-80 -60 -40 -20 0 20 40 60 80
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T / C
Tg 28°C
Tg -41°C
0
30
60
90
0.1
1
10
100
1000
10000
-80 -60 -40 -20 0 20 40 60 80
los
s a
ng
le /
°
E', E
" / M
Pa
T / °C
E'
E"
Delta
Supramolecular self-healing materials -
morphology
OsO4 stains preferentially the charged
domains
The different domains can be differentiated
in the morphology of the material
The diffractogram gives evidence of
repeating structure and indicates distances d
(6-10nm)
Poster: A new class of supramolecular
thermoplastic elastomers for self-healing coatings
Lenny Voorhaar & Maria Mercedes Diaz
TEM micrograph
Performed in EMAT-UA
Supramolecular self-healing materials -
morphology
max
2
qd
Repeating structure confirmed by SANS
Repeat distances d of 8-9nm are
observed.
Small Angle Neutron Scattering
(SANS)
Performed in ISIS by Dr. Rogers
0.1
1.0
10.0
0.01 0.1 1
I /
cm
-1
q / Å-1
Concept:
Rupture
Tamb
Healing
T> 2nd
Tg
↓scratch ~50μm wide Healing at 43°C
after 20min.
Supramolecular self-healing materials –
self-healing
Healing
T> 2nd
Tg
Supramolecular self-healing materials –
tuning network properties
0.1
1
10
100
1000
10000
-80 -60 -40 -20 0 20 40 60 80
E' /
MP
a
T / °C
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-80 -60 -40 -20 0 20 40 60 80
He
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-1
T / C
• Changing the length of the end blocks allows
tuning network properties
+ +
+ +
+ +
+ +
- - - -
- - - -
0.1
1
10
100
1000
10000
-80 -60 -40 -20 0 20 40 60 80
E' /
MP
a
T / °C
0.1
1
10
100
1000
10000
-80 -60 -40 -20 0 20 40 60 80
E' /
MP
a
T / °C
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-80 -60 -40 -20 0 20 40 60 80
He
at
ca
pa
cit
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-1C
-1
T / C
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-80 -60 -40 -20 0 20 40 60 80
He
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ca
pa
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-1
T / C- - - -
- - - -
+ +
+ +
+ +
+ +
The length of the
charged blocks -> Tg
change and
mechanical properties