Molecular Mobility in Polyelectrolyte Multi-Layers and ...graf/talks/PEM03.pdf · Molecular Mobility in Polyelectrolyte Multi-Layers and Heterogeneous Polymers Robert Graf MPI for

Molecular Mobility in

Polyelectrolyte Multi-Layers

and Heterogeneous Polymers

Robert GrafMPI for Polymer Research, Mainz, Germany

I. Polyelectrolyte multi-layers• Introduction• Local structure of layered systems• Polymer mobility in PEMs• Water mobility in PEMs• PEM Summary

II. Heterogeneous Polymers• Poly-phenylenes with PEO sidechains• Information from separate local field experiments• Recoupled polarization transfer experiments• Order-parameters from 1H double quantum NMR• Conclusions

Polyelectrolyte Multi-Layers

Structure of Polyelectrolyte Layers

DQ NMR Investigation of Structure: PEM vs. PEC

N+

SO O

O-

HH

HH

H

H

H

H

H3C CH3

Polyelectrolyte MultilayerPolycationSolution

PolyanionSolution

Anionic Substrate

Aqueous Rinse

After 3 cycles

Polyelectrolyte Complex

PolyanionSolution

Polyelectrolyte Complex Formation

9 8 7 6 5 4 3 2 1

2

4

6

8

10

12

14

16

18

Single Quantum Dimension [ppm]9 8 7 6 5 4 3 2 1

Single Quantum Dimension [ppm]

Double

Quantu

m D

imen

sion [

ppm

]

2

4

6

8

10

12

14

16

18

Double

Quantu

m D

imen

sion [

ppm

]

PolycationSolution

After Drying

Molecular Dynamics in Polyelectrolyte Multi Layers

N+

HH

HH

H 3C CH 3

SO O

O-

H

H

H

H

1 2 3 4 5 6 7 9 108 C

PSS 500 MHzPDADMAC 500MHzPSS 700 MHzPDADMAC 700MHz

200

400

600

800

1000

Number of Layers

T1

[mse

c]

Spin-LatticeRelaxation

10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5

0,01

0,1

1

10

500 MHz700 MHz

correlation time τ [s]

T 1[s

]

theoretical T1 relaxation behavior:

Water Mobility in Polyelectrolyte Multilayers

1 2 3 4 5 6 7 9 108 CNumber of Layers

T1

[mse

c]

200

300

250

350

400

550

600

Spin-Lattice Relaxation

Number of Layers

1 2 3 4 5 6 7 9 108 C

60

70

80

90

100

110

Linew

idth

at F

WH

H [

Hz]

Linewidth (apparent T2)

50

40

Localization of Water in Polyelectrolyte Multilayers

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Layer 7

Layer 8

Layer 9

Layer 10

ppm12 10 8 6 4 2 0

5.0

4.8

4.6

4.4

4.2

4.0

3.8

3.6W

ate

r Che

mi c

al S

hift

[ppm

]

1 2 3 4 5 6 7 8 9 10Layer Number

bulkPDADMAC

bulk PE C

bulk PS S

SO O

O-

H

H

H

H

N+

HH

HH

H3C CH3

8 7 6 5 4 3 ppm

1H MAS NMR Spectra 1H Chemical Shift

Polyelectrolyte Multi-Layer SummaryI. Complexation:

(i) Polycation-polyanion complexation of polyelectrolyte multi-layers (PEM) is similar to that in the bulk polyelectrolyte complex (PEC).

(ii) Water-polymer association in PEMs is much stronger than in PEC.

II. Polymer Dynamics:

(i) Addition of water increases the polymer mobility in PEMs but not in the PEC.

(ii) Enhanced polymer mobility is observed for hydrated PDADMAC-capped films relative to PSS capped films.

(iii) This oscillation in the polymer mobility dampens and is superimposed on a gradient of decreasing mobility with film thickness. No changes with layer number are observed for dry films.

II. Adsorbed Water:

(i) Mobility of adsorbed water is more restricted in PEMs than in the PEC.

(ii) Water mobility is lower and water content is higher in PSS capped films as compared to PDADMAC capped PEMs.

(iii) 1H NMR peak intensity increases monotonically and its chemical shift oscillates between the PEC bulk and the bulk PDADMAC value.

I. Polyelectrolyte multi-layers• Introduction• Local structure of layered systems• Polymer mobility in PEMs• Water mobility in PEMs• PEM Summary

II. Heterogeneous Polymers• Poly-phenylenes with PEO sidechains• Information from separate local field experiments• Recoupled polarization transfer experiments• Order-parameters from 1H double quantum NMR• PP-PEO Summary

NMR Investigation of Moelcular Dyamics in PPPEO4

406080100120140160 ppm

nO

O

O...

A

O

O...

A A AB

BC C

C C D

D

E

E

E

F

F

GA B C

D

E

F G

Molecular Dynmiacs via Separate Local Field NMR

CP

CP

t1

n·τR n·τRtm t2

dipolar decoupling1H

13C

kHz

4080120160 ppm

-30

-20

-10

40

30

20

10

0

carbon chemical shift

C D E F

1 H s

ideb

and

patte

rnnO

O

O...

A

O

O...

A A AB

BC C

C C D

D

E

E

E

F

F

G

1H sideband pattern from SLF NMR Experiments

low molecular mobilityhigh mobility high mobility

Local Dynamics via RePT-HDOR Sideband Pattern

-150 -100 -50 0 50 100 150

ω [kHz]

-150 -100 -50 0 50 100 150ω [kHz]

T = 230 K T = 270 K T = 300 K

Phenyl CH(bound to PEO)

-150 -100 -50 0 50 100 150

ω [kHz]-150 -100 -50 0 50 100 150

ω [kHz]

ω [kHz]-150 -100 -50 0 50 100 150

Phenyl CH

C

-150 -100 -50 0 50 100 150

ω [kHz]

D

Dij=21 KHz

Dij=21 KHz Dij=21 KHz

Dij=22 KHz Dij=12 KHz

Dij=18 KHz

rigid

rigid

rigid

rigid

180°-flips +fluctuations

fluctuations

Molecular Dynamics of PPPEO via 1H DQ NMR

260 300 340 380

0,1

1

PEOPP

orde

r par

amet

ertemperature [K]

220 260 300 340 3800,0

0,2

0,4

0,6

0,8

1,0

temperature [K]

orde

r par

amet

er

PEOPP

nO

O

O

...

A

O

O

...

A A AB

BC C

C C D

D

E

E

E

F

F

G

activation ofmain chain dynamics

Polyphenylene - Polyethylenoxide Summary

I. Qualitative information about dynamics via separate local field experiments :

(i) At room temperature, the Poly-(Ethylene oxide) (PEO) chains and unsubstituted phenyl rings of the polymer backbone are highly mobile.

(ii) The first CH2 group of the PEO side chains bound to phenyl rings of the Poly-Phenylene(PP) backbone and these phenyl rings are less mobile.

II. Identification of dynamic processes via recoupled polarization transfer NMR experiments :

(i) For temperatures below 300K, the PP backbone is rigid.

(ii) For T > 290K substituted phenyl groups, bound to PEO side chains, show substantial fluctuations.

(iii) Unsubstituted phenyl groups undergo additional phenyl flips around the chain axis.

II. Bending dynamics of the poly-phenylene main chain via 1H double quantum NMR:

(i) For T > 300 K bending fluctuations of the PP backbone are observed.

(ii) The loss of dynamic anisotropy with increasing temperature is more pronounced for the PEO side chains the for the PP backbone of the polymer.

Acknowledgements

Prof. Hans-Wolfgang SpiessDr. Robert Graf

Polyelectrolyte Multi-Layers :

Dr. Mark McCormickProf. Linda Reven, McGill University, Toronto, Canada.Rashida Smith, McGill University, Toronto, Canada.

PP-PEO Dynamics:

Michael NeidhöferProf. George Floudas, FORTH, Heraklion, Greece.Prof. Gerhard WegnerDr. Ulrich Lauter