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NMR Investigations of Self-healing Processes in Supramolecular Elastomers Kay Saalwächter PowerPoint Presentation
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Observables/Methods. motion of/within supramolecular links (high-res. MAS NMR) phase composition, domains (low-resolution 1 H NMR) monomer-scale detection of chain motion ( 1 H MQ-NMR) macroscopic mechanical and self-healing behavior (rheology).

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slide1

Observables/Methods

  • motion of/within supramolecular links (high-res. MAS NMR)
  • phase composition, domains (low-resolution 1H NMR)
  • monomer-scale detection of chain motion (1H MQ-NMR)
  • macroscopic mechanical and self-healing behavior (rheology)

NMR Investigations of Self-healing Processes in Supramolecular Elastomers

Kay Saalwächter

Structures relevant for self-healing elastomers

[entangled melt]

[permanent network]

supramolecular network

(homogeneous)

supramolecular network

(nanophase-separated)

hybrid network

SPP 1568: “Design and Generic Principles of Self-healing Materials”

new proposal

slide2

1H high-resolution

MAS NMR

7

10

permanent

elastic plateau

6

10

H-bonds

5

10

cool

G’, G'' at 1 rad/s (Pa)

heat

4

10

G’

self-healing

rubber

3

10

G’’

2

10

0

20

40

60

80

100

120

140

160 °C

NMR experiments on stretched rubbers

28mm

local stretching by MQ NMR

8mm

2.0

unstretched

R

1.5

a

stretched l=2

1.0

probabilty

classical

affine model

0.5

phantom model

0.0

stretching/com-pression device

0

1

2

3

4

5

Dres/Dres,l=1

R. Pérez-Aparicio et al., Macromolecules46, 5549 (2013)

Relevant previous work

ageing in Leibler’s self-healing rubber

R. Zhang et al., Macromolecules46, 1841 (2013)

slide3

reference

direction

time-dependent orientation

autocorrelation function

Ca(t) = < P2(cos a0)P2(cos at)>t,n,N

fast segmental

motions (ns-ms)

a(t)

log Ca

reptation, cooperative

processes (ms-s)

~1%

network:

S2 plateau

log time

  • residual average orientation
  • ~ semilocal backbone order parameter
  • dependent on N-1 (~ ne/c ~ 1/Me/c )
  • NMR-observable dipolar coupling Dres

~ line width ~ 1/T2

!

Orientation correlations in polymers

polymer melt far above Tg:

n entangled/x-linked chains,

Nsegments each

slide4

7

10

permanent

elastic plateau

6

10

5

10

cool

  • implement analytical theory
  • use in fits to various materials
  • determine bond life-time tb

G’, G'' at 1 rad/s (Pa)

heat

4

10

G’

C(t) for supramolecular rubber:

self-healing

rubber

3

10

G’’

tb(T)

elastic plateau

2

10

0

20

40

60

80

100

120

140

160 °C

Sb2 ~ 1/Nb2

permanent

crosslinks

vs. flow

correlate

tR(M)

td(M)

Segmental orientation correlation function

MQ NMR probes fast and slow chain dynamics

10 0

0

10-1

10-2

I

10-3

C(t/te)

experimental (linear PB):

10-4

FFC NMR (3 kDa, 11 kDa)

MQ NMR (87 kDa)

constructed (linear PB):

10-5

2000 kDa

II

III-IV

87 kDa

10-6

35 kDa

ts

te

10-7

10-5

10-4

10-3

10-2

10-1

100

101

102

103

104

105

106

107

108

109

t/te

F. Vaca-Chavez, KS, Phys. Rev. Lett. 104, 198305 (2010); Macromolecules44, 1549 & 1560 (2011)

slide5

Collaborations within the SPP 1568

Samples from other projects

  • W. Binder: H-bonded supramolecular thermoplastic elastomers and ionomers based upon PIB
  • F. Böhme/G. Heinrich:self-healing ionic liquidsbased upon PIB)
  • A. M. Schmidt: ionomeric elastomers based upon PBA and hydrogenated NBR

Complementary methods

  • W. Pyckhout-Hinten: neutron scattering, rheology
  • W. Paul (new): theory support
  • C. M. Papadakis/B. Rieger (new): X-ray scattering, rheology