Poster apme 2017 bewi

1. Spontaneous moisture-driven healing of urea-based polyurethanes
Bertrand Willocq1*, Farid Khelifa1, Vincent Lemaur2, Philippe Leclère2, Jérôme Cornil2,
Philippe Dubois1,3 and Jean-Marie Raquez1
1. Center of Innovation and Research in Materials and Polymers CIRMAP, Laboratory of Polymeric and Composite Materials, UMONS University of Mons, Place du Parc 23, Mons, Belgium
2. Center of Research in Molecular Electronics and Photonics, Laboratory for Chemistry of Novel Materials, UMONS, University of Mons, Place du Parc 23, Mons, Belgium
3. Department of Materials Research and Technology, National Composite Center-Luxembourg, Luxembourg Institute of Science and Technology, 41 rue du Brill, Belvaux, Luxembourg
*Contact email : bertrand.willocq@umons.ac.be
REFERENCES
[1] S. Billiet et al., Macromolecular Rapid Communications 2013, 34, 290-309; B. J. Adzima et al. Advanced
Materials 2010, 22, 2784-2787; L. Huang et al., Advanced Materials 2013, 25, 2224-2228; L. He et al.
Chemical Communications 2011, 47, 7497-7499; B. Willocq et al., Journal of Materials Chemistry A 2016, 4,
4089-4097.
ACKNOWLEDGMENTS
LPCM thanks the Belgian Federal Government Office of Science Policy (SSTC – PAI 6/27) for general support and
is much indebted to both « Région Wallonne » and the European Commission « FSE and FEDER » for financial
support in the frame of Phasing-out Hainaut. B. Willocq is FRS-FNRS PhD student and J.-M. Raquez is FRS-FNRS
research associate.
INTRODUCTION
SPONTANEOUS HEALING MECHANISM BASED ON UREA
QUANTITATIVE SCRATCH RECOVERYQUALITATIVE SCRATCH RECOVERY WITH HUMIDITY
Up to now, the majority of the proposed self-healing principles for polymers relies on energy-demanding activations to promote the self-healing mechanisms.[1] Here, we report on the
efficient, spontaneous, and repetitive healing of an urea-based polyurethane film when scratched and exposed to atmospheric humidity. Repairs rely on the separation of
hydrogen-bonded urea moieties by a cut and a subsequent spontaneous formation of supramolecularly-driven water-urea clusters that bridge the crack and induce the complete gap
closure when water gets evaporated. We illustrate this approach with a non-hygroscopic urea-based polyurethane by repetitive scratch-healing tests at different degrees of humidity.
As a simple, rapid, and spontaneous way to heal a polymer, the new route presented herein is of high interest for anti-corrosive coatings, under-water sealants or technologies requiring
soft hydrophobic and healable materials.
Freshly cut material Water intake
and local increase of mobility
Healed material
Free-urea Water-urea clusters Associated urea
SYNTHESIS OF UREA-BASED POLYURETHANES
+
(45%wt)
Polypropylene glycol
2000g/mol
(30%wt)
(25%wt)
+
N2, DMF, DBTDL (cata.)
65°C, 6h
 Non-hygroscopic
 Insoluble in H2O
 Mobility (Tg = 12°C)Urea-based PU
40%HR
18h
0%HR
18h
40%HR
18h
Optical microscopy
• Moisture and urea as part of the healing
Urea-based PU
Reference PU
t = 0h
25%HR
Scan size : 3.5µm
t = 18h
t = 0h t = 18h
15nN
0.1nN
Adhesion
25%HR
Topography
• Peak-force AFM on coatings (1µm)
 Quantitative scratch recovery
 Recovery of mechanical properties
 Similar trend for bulk materials
Free-urea Re-associated urea
• Adhesion recovery of coatings
• Free-urea increase adhesion within scratches
INVESTIGATION OF HEALING MECHANISM
2
1 Water-urea interactions?
Urea release on damaged surfaces?
1 Infrared spectroscopy in solution with increasing water content
Urea band shift when interacting favorably with water
(in line with DFT calculations)
2
PRISTINE
water
IR spot
CUT
water
water
IR spot
1560 1550 1540 1530
1546.02
1543.41
cut
pristine
2000 4000 6000 8000 10000
0
20
40
60
80
100
Humidity ratio
Virgin sample (smoothed)
Scratched sample (smoothed)
Time (second)
Humidityratio(%)
0
2
4
6
8
Waterintake(%weight)
Damaged
film
Undamaged
film 0% 50% 100%
+3%
Quartz-microbalanceInteraction of released urea
with water
Wavenumber (cm-1)
Urea-water interaction on damage-released urea
Different water uptake
1750 1700 1650 1600 1550 1500
Wavenumber (cm-1)
Solution THF
Solution THF + 10µl H2O
Solution THF + 100µl H2O
Urethane Water
Urea