16 March2021, remotely © F. Ganachaud 1
Thermoplastic silicone elastomers:
an endless story
F. GANACHAUDUniversité de Lyon, Ingénierie des Matériaux Polymères, CNRS UMR 5223,
IMP@INSA, Villeurbanne, France
Elasto-Plast final meeting, remotely, 16 March 2021
Dedicated to the memory of Jean-Pierre PASCAULT
16 March2021, remotely © F. Ganachaud 2
Silicone TPEs are hardly commercialized at the moment
so this speech mainly cover academic works
• F. Ganachaud, Thermoplastic silicone elastomers: an endless story,
L’actualité Chimique, n°456-458, 74-81 (2020/2021) (in French)
Submitted to JAST (2021) (in English)
• B. Yi et al, Dynamic siloxane materials: from molecular engineering to emerging applications,
Chemical engineering Journal, 405, 127023 (2021).
• Z. Wang et al, Preparation, characterization and properties of intrinsic self-healing elastomers,
Journal of Materials Chemistry B, 7, 4876-4926 (2019).
Focus mainly on mechanical properties
16 March2021, remotely © F. Ganachaud 3
✓ Context
Supramolecular chemistry and silicone TPEs
Speech overview
✓ Applications
Electronics, antifouling, shape memory….
✓ Silicone urea (co)polymers
Functional silicones, multiblock copolymers, self-healing
✓ New chemistries
Ionic pairing, metal-ligand,(covalently-reversible) vitrimers
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Context
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✓ : High flexibility, Tg < -120°C
✓ Rubber-like, semi-organic materials, filled with silica
✓ Chemically inert, biocompatible, high gas permeability
✓ Low modulus (few MPa), hyperelasticity, large strain at break (>1000%)
Silicone elastomers
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50 nmSi
O
H
O
SiSiO2
O
SiO
O
H
H
B
Réticulation
ROOR, ∆Groupements D
Groupements Dvi
A
D units
DVi units
Crosslinking
ROOR,
Conventional silicone elastomers vs TPE
C
0 200 400 600 8000
2
4
6
8
10
12
Co
ntr
ain
te (
MP
a)
Elongation (%)
A
A+B
Ten
sile
stre
ngt
h(M
Pa)
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Supramolecular chemistry
ion - ion 100 - 350 kJ/mol
ion - dipole 50 - 200 kJ/mol
dipole - dipole 5 - 50 kJ/mol
Physical interactions
Covalent bond 200 - 400 kJ/mol
H bonding
(alcohol – acid)
5 - 120 kJ/mol
(15 – 60kJ/mol)
0 - 50 kJ/mol - stacking
0 - 5 kJ/molVan der Waals
A large range of available reversible links
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Block copolymer nanostructuration OR association through weak interactions
Supramolecular materials
Various possibilities
H bond growing in two directions
(Pseudo)-ionic pairs very stable
Others (A/D, - stacking…) + combinations
Flexibility and robustness
Functional group location
Multiple interactions in polymers
Phase demixion helps the structuration
Reversibility
8
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Self-assembly of silicones: « Silly putty » (1943)
Si-OH B
OH
OHHO
Rapid stress behaves like an elastic gel
Slow stress behaves like a viscous liquid
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Self healing systems: living polymer network
P. S. Chang, M. A. Buese, US patent 5,347,028 /JACS, 1993, 115, 11475-11484.
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Silicone ureas
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Brief survey
✓ Two main categories
Modified silicone backbone vs multiblock copolymers
✓ Versatile chemistry
Amine + various diisocyanates…
✓ Inspired from polyurethane TPEs
Seminal work of Yilgor and Yilgor
Soft segment Urea content
(%)
Tensile strength
(MPa)
Strain at break
(%)
PSU-DY-20 PDMS 20 7.9 205
PSU-HM-20 PDMS 205 8.1 195
PSU-ED-19 PDMS 19 8.3 180
PEU-DY-20 PEO 20 25.4 1320
PEU-HM-20 PEO 20 25.8 1325
PEU-ED-19 PEO 19 26.5 1450
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Functional silicones
O. Colombani et al Macromolecules 2005, 38, 1752
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T decrease
T increase
Free
Free
Bonded
Bonded
1800 1750 1700 1650 1600 1550 1500 1450
0,0
0,1
0,2
Absorb
ance
30°C
50°C
70°C
90°C
110°C
130°C
160°C
Wavenumber (cm-1)
1800 1750 1700 1650 1600 1550 1500 1450
0,0
0,1
0,2
Ab
so
rban
ce
Wavenumber (cm-1)
160°C
130°C
90°C
62°C
32°C
Functional silicones (bis)
Degradation of the material above 180°C
=> Chemical cross-linking
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Silicone ureas’ copolymers
GENIOMER (Wacker)
O. Schäfer, J. Weis, S. Delica, F. Csellich, A. Kneissl Polym. Prep. 2004, 45(1), 714
Synthesis in solution (IPA) or in reactive extrusion
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0 200 400 600 800 1000 1200 14000
2
4
0.01 s-1
0.08 s-1
No
min
al S
tre
ss,
N,
[MP
a]
Nominal Strain, N,[%]
0.1 s-1
0 10 20 30 40 500,00
0,05
0,10
0,15
0,20
0,25
Stre
ss [
MPa]
Strain [%]
Real life properties
0 200 400 600 800 1000 1200 1400
0
1
2
3
4
5
6
Str
ess (
MP
a)
Strain (%)
G200
G145
G80
G345
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Isocyanate-free silicone urea
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0
0,.1
0,.2
0,.3
0 300 600 900
+
92 %
8 %
Stre
ss (
MPa
)
Strain (%)
Implementing self-healing
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Other chemistries
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Brief survey
✓ Pairing with metals
Direct ion pairing or metal-ligand specific interactions
✓ Reversible covalent bonds
Following the trend of vitrimers
✓ Ionic interactions put on success
As strong bonds as covalent ones
✓ Possibility to add fillers!
Little interactions with associating groups
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Zwiterionic polymers
Δ
1. Acid-base reaction
2. Aza-Michael reaction
K = 2.105 – 6.107
0 1000 2000 30000.0
0.1
0.2
0.3
0.4 0.008 s-1
0.08 s-1
0.25 s-1
0.42 s-1
No
min
al S
tress,
N, (M
Pa)
Nominal Strain, N, (%)
Press
UnloadFeed
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Metal ligand interactions
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Thermoreversible covalent link (old version)
Diels-Alder Esters
O
+
R
O O
OHHO
nHOOC O
OR
OO COOH
CH2 X + R2N X CH2 NR2n m
NR+
NR+
NR2+
X-
X-
X-
Ionene Azlactone
Hydrazone
R1 NH NH2 + C
O
H
R2 R1 N N
H
C
O
R2
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Thermoreversible covalent link (new version)
Vinylogous Imine
Disulfide
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High performance applications
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Brief survey
✓ High-tech applications
Batteries, dielectric actuators, electronic sensors…
✓ Coatings and bulk materials
From anti-icing to shape-memory materials
✓ Playing with specific properties
Processability, self-healing, high stretch
✓ Challenge: 3D printing
Fused deposition modeling
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Coatings
Anti-icing
Anti-fouling
+Self-healing avoidsunwanted adhesion
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Materials
Shape memory
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Conclusion and prospects
➢ Silicone is ideal to generate TPEs
Very low polarity efficient demixing and self-assembly
➢ Versatility of chemical modifications
From weak forces to disruptable covalent links
➢ Still need improvement to compete with silicone elastomers
Weak mechanical properties fillers
Thermal resistance new chemistry?
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At IMP (if you are interested)
J. Mater. Chem., 2010, 20, 10269-10276.
Chem. Commun., 2016, 52, 6681-6684
In progress
WO 2016102498 A1J Colloid Interface Sci. 2013, 408, 87-93
+ Patent pending
In Silicon Based Polymers, 2008, pp 85-98
FR2912410 (A1)
H-Bonding Others
Ionic pairing
III III
16 March2021, remotely © F. Ganachaud 31
Thermoplastic silicone elastomers:
an endless story
F. GANACHAUDUniversité de Lyon, Ingénierie des Matériaux Polymères, CNRS UMR 5223,
IMP@INSA, Villeurbanne, France