Investigation of Structure and Dynamics in Polymeric Systems via Solid State NMR

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1 Investigation of Structure and Dynamics in Polymeric Systems via Solid State NMR Robert Graf Max-Planck-Institut für Polymerforschung Mainz March 2 nd, 2005

2 Max Planck Institute for Polymer Research founded 1983, 450 co-workers, on campus of the University of Mainz, interdisciplinary fundamental research of polymers

3 Max Planck Institute for Polymer Research Materials Science Theory Board of Directors MPI-P SynthesisOrganization Spectroscopy Solid State Chemistry Polymer Physics Knoll Kremer Müllen Spiess Wegner Butt igh Resolution NMR Optical Spectroscopy Thin Films Mass Spectrometry Polymer Synthesis Supramolecular Architecture Microscopy Polymer Analysis Surfaces and Interfaces Scientific Project Areas Structure and Dynamics Functional Materials Development of Methods X-Ray Structure Analysis Computer and Network Service Clean Room Mechanical and Dielectric Relaxation

4 Scientific Activities of the MPI-P Spectroscopy Group Structure and Dynamics Polymer Synthesis Polymer Chain Dynamics Local-Order Phenomena Polymerization: Radical, Anionic, Emulsion, Atom-Transfer Radical Isotopic Labelling Photoconductors Protonconductors Shape-Persistent Macromolecules Spectroscopy Group Development of Methods 2D Multiple Quantum MAS NMR Imaging of yperpolarized Gases DFT Calculations Pulsed and CW EPR Fourier-Transform Rheology Polyelectrolyte Multilayers Self Assembled Monolayers Surface Patterning Columnar π-π Stacking ydrogen-bonded Structures Coordination Polymers Surfaces & Interfaces Functional Materials Supramolecular Architectures

5 Investigation of Structure and Dynamics in Polymeric Systems via Solid State NMR Introduction Solid State NMR interactions in solid state NMR resolution enhancement in solid state NMR, magic angle spinning, recoupling methods, double quantum NMR spectroscopy Polymer dynamics Conclusions Polyelectrolyte layers, polybutadiene, PEMA Pro and Contra of Solid State NMR investigations

6 Molecular Structures and Dynamics via NMR Important NMR interactions: = Z + Q + CS + D + J Zeemann Interaction : Quadrupol Interaction : Electronic Shielding : Dipol-Dipol Interaction : Z Q CS = γ i = γ i i i B B 0 0 I eq = 2I(2I 1) h i i σi I i i VI i [ ] 3 i j i j ( I r)( I r I μ h γiγ j D = 4π 3 ) r r i j 0 I 2 Indirect Spin-Spin Interaction : J = i j I i J ij I j

7 Interactions in Solid State NMR Spectroscopy Zeemann interaction dominates all other NMR interactions Perturbation Theory Orientation dependence of local spin interaction on B 0 Q, D, CS, J Isotropic Contributions CS : chemical shift J : J-couplings Liquid state NMR B 0 B 0 θ θ Anisotropic Contributions Symmetric Asymmetric Q : quadrupol Q : quadrupol D : dipol-dipol CS : chemical shift CS : chemical shift i j 1 2 D = μ h γ γ 4π r 2(3cos θij 1) ij i j 0 T 3 Distance Orientation ij 2,0

8 1 NMR Spectra in Liquid and in Solid State static dipolar broadening kz 30 kz MAS kz rigid solid RMAS 4 3 kz soft matter Solution 5 0 kz isotropic molecular dynamics

9 Spectral Resolution Enhancement in Solid State NMR dipol-dipol coupling: i B 0 θ ij magic angle spinning: j space spin 1 $ 1 ( 3cos 2 θ 1) γ γ ( 3$ I $ I $ I $ I ) r 3 ij 2 $ = R$ T$ 20, 20, ij i j Z, i Z, j i j B 0 B 0 B 0 B 0 θ m θ θ m R$ 20, 0 ω R ω R ωr RF irradiation: -x y -y x -x y -y x -x y -y 0 T$ 20, (CRAMPS) τ τ 0 t C 2τ τ τ τ τ 2τ τ τ τ τ 2τ τ x -xy -y t C x -xy -y x -xy t D,eff. (Recoupling) τ τ τ τ τ t 0 t R t R

10 Double Quantum NMR Spectroscopy under MAS preparation evolution t 1 reconversion detection t 2 properties of double quantum coherences : C C 2 ω I DQ DQ ij = ω, i SQ i, = f( Dij t) dm dt 0 -C 2 C 2 -C C=C ppm ppm single quantum dimension (f 2 ) double quantum dimension (f 1 )

11 Molekulare Stuktur von Silikat-Schichten 29 Si double quantum spectrum: DQ intensity r -6 => coordination shells Double quantum dimension Q 4 Q 3 Single quantum dimension ppm Analysis of layered silicates via next nearest neighbor relations

12 Molecular Structure of Layered Silicates 29 Si double-quantum spectrum: DQ-Intensities => coordination spheres B C double quantum dimension A E D single quantum dimension structure of layered silicates from analysis of spatial proximities N. edin et al., J. Am. Chem. Soc. 126, 9425 (2004).

13 Polybenzoxazines Useful Properties igh T g Good mechanical properties Excellent UV and chemical resistance Unusual Properties Low water absorption Low volumetric expansion on curing igh modulus O R N Ring Opening O N O X R X X n-1 ydrogen-bonded network What is the nature of the network?

14 Benzoxazine Oligomers Studied by 1 DQ NMR Dimer Trimer Tetramer Changes in hydrogen bonding structure evident from changing 1 resonances and DQ contacts

15 ydrogen Bonds Assigned via DFT-Based Chemical Shift Calculations Dimer Trimer Tetramer Calculated and experimental 1 NMR spectra agree, particularly in hydrogen-bonding region. Isolated Dimer Pair - X-ray Structure Intra:Inter = 1:1 Trimer forms Planar Ring Intra:Inter = 2:1 Tetramer forms Overlapping Loop Intra:Inter = 3:1 1 chemical shifts influenced by proximity to oxygen. elical structure predicted for polymer. G. R. Goward et al., J. Am. Chem. Soc. 125, 5792 (2003).

16 Order Parameter in Liquid Crystalline Phases 2.54 Å F D 1.83 Å C B 2.49 Å chemical structur of nematic model compound A 2.48 Å order parameter S ij : S ij = ij 1 2 S = (3cos c D D 2 ij,eff ij,stat C θ 1) 1.83 Å E D F 2.56 Å G G-G F-F E-E D-E D-D C-D B-C A-C F D C E A B G ppm ppm double quantum dimension single quantum dimension

17 Order Parameters in Liquid Crystalline Systems DQ sidebands BC DQ coherence F D C B A orientation of nematic director C E D F G kz 0.6 DQ Intensity [a. u.] 0,5 0,4 0,3 0,2 0,1 DQ intensity BC DQ coherences order parameter S ,0 0,0 0,1 0,2 0,3 0,4 0,5 0,6 DQ-Preparation Time [ms] 0.0 A-C B-C D-D E-E F-F G-G

18 Investigation of Structure and Dynamics in Polymeric Systems via Solid State NMR Introduction Solid State NMR Polymer Dynamics Conclusions Interaction in solid state NMR MAS, recoupling, double-quantum NMR Polyelectrolyte multi layers,reptations-model, scaling laws in polymer dynamics, influence of rigid confinements, conformational stability in PEMA melts. Pro and Contra Solid State NMR investigations

19 Polyelectrolyte Multi-Layers

20 Structure of Polyelectrolyte Layers

21 DQ NMR Investigation of Structure: PEM vs. PEC Polyelectrolyte Complex After 3 cycles Anionic Substrate Polyelectrolyte Multilayer Polycation Solution Polycation Solution Polyanion Solution After Drying Aqueous Rinse Polyelectrolyte Complex Formation Polyanion Solution Double Quantum Dimension [ppm] N + 3 C O - C 3 O S O Double Quantum Dimension [ppm] Single Quantum Dimension [ppm] Single Quantum Dimension [ppm]

22 Molecular Dynamics in Polyelectrolyte Multi Layers T 1 [msec] PSS 500 Mz PDADMAC 500Mz PSS 700 Mz PDADMAC 700Mz T 1 [s] theoretical T 1 relaxation behavior: ,1 500 Mz 700 Mz Spin-Lattice Relaxation 0, C N + C 3 C 3 Number of Layers O O - S O correlation time τ [s]

23 Localization of Water in Polyelectrolyte Multilayers Layer 1 O O - S O N + 3 C C 3 Layer 2 Layer 3 Layer 4 Layer ppm Layer 6 Layer 7 Layer 8 Layer 9 Layer ppm Water Chemi cal Shift [ppm ] Layer Number bulk PDADMAC bulk PE C bulk PSS 1 MAS NMR Spectra 1 Chemical Shift M. McCormick et al., Macromolecules 36, 3616 (2003). S. Pawsey et al., J. Am Chem. Soc. 125, 4174 (2003).

24 Length- and Time Scales in Polymer Dynamics dynamic regimes of the Reptation model : I. II. III. IV. log [R n (t)-r n (0)] 2 t 1/4 t 1/2 t t 1/2 t < τ e fast, local dynamics τ e τ R log(t) τ d t > τ e slow, collective Reptation dynamics separation of time scales!

25 DQ Measurements of Dynamics on Different Time Scales ( 2) ( 2) I dt dt D d ( t ) d ( t ) DQ t 0 2t+ t t+ t ij, eff 2, m 2, m t = 0 t τ e t > τ e θ(t 1 ) θ(t 0 ) θ m + α(t) local order parameter : static systems : isotropic motion : S = ij Dij, eff / Dij S ij (t)=1 S ij (t)=0 polymer network theory : S N e Polybutadien : S M M 3 Kuhn e ( 2) ( 2) d ( t ) d ( t ) 2, m exc. 2, m rec. corresponds to return-to-origin probability C (t) t

26 Local Order Parameters in 1,4 Polybutadien Melts 1 double quantum NMR spectrum Dynamic order parameter via residual dipolar couplings C C 2 S -C 2 C 2 -C C=C ppm single quantum dimension (f 2 ) ppm doubel quantum dimension (f 1 ) S - = 0.13 T=T g +50K S = S = S C=C = 0.20 ± 0.05

27 Time Dependence of Local Order Parameter double-quantum filtered experiments on 1,4 poly-butadien t c ( ) t c ( ) 1,0 ~ t -1/4 C (t) 0,1 PB M W 76 M e PB M W 11 M e PB M W 4 M e ~ t -1/ t / t e (T) Reptation-model predicts two scaling laws: S~t -1/4 and S~t -1/2 R. Graf et al., Phys. Rev. Lett. 80, 5738 (1998).

28 Molecular Weight Dependent Dynamics of PB Melts in PS-PB 1 10 ~t 1/4 S(t/t e ) D C=C / kz 0.01 PS-b-PB 12k-10k PS-b-PB 22k-24k PS-b-PB 90k-120k t/ t e Tethering a PB chain end to a rigid PS block stabilizes the t -1/4 -regime

29 Influence of Rigid Confinements on Polymer Dynamics 1 10 S(t/t e ) C=C PB PS-b-PB PS-b-PB-b-PS ~ t 1/ PB PS-b-PB t / t e ~ t 1/ D C=C / kz PS-b-PB-b-PS T. Dollase et al., Macromolecules 34, 298 (2001).

30 Polymer Dynamics in heterogeneous Polymer Melts 1 10 S(t/t S(t/τ e e ) C=C ) PB ~t 1/2 PS-b-PB p 6 (12k-10k) 5 % PB p 6 in PS-b-PB d 6 PB p 6 (10k) ~t 1/ t / t / τ e e PS-b-PB D C=C / kz PB in PS-b-PB

31 Variation of Dynamic Order Along the Polymer Chain S(t/t e ) 10-2 ~ t -1/ chain end chain center whole chain ~ t -1/ t / t e PB(d 6 )-PB PB(d 6 )-PB-PB(d 6 ) PB

32 a-pema: Isotropisation of Chain Dynamics C 180 O 472 K 433 K Melt 411 K 50 ω 13 C O ω 405 K Melt K ω <10 13 C 180 ω 33 O ω 11 ω K 298 K ω 11 1D 13 C NMR: ω ω 22 ω experiment simulation T g Glass

33 a-pema: Isotropisation of Chain Dynamics <10 13 C ω ω 22 ω 11 O ω 11 ω 22 ω ω ω C O ω ω C 180 O [ppm] ω T = 300 K [ppm] ω T = 394 K [ppm] ω T = 416 K [ppm] ω t c = 3, s [ppm] ω t c = 2, s [ppm] ω 1

34 Dynamic Models: Random Jump vs. Rotational Diffusion rotational diffusion experimental results random jump [ppm] t c =8, s [ppm] T = 405 K [ppm] t c =8, s [ppm] [ppm] [ppm] [ppm] t c =3, s [ppm] T = 394 K [ppm] t c =3, s [ppm] [ppm] [ppm] M. Wind et al., Solid State NMR 27, (2005).

35 Time Sclaes of Molecular Dynamics PEMA Melts 10 2 T g = 338K 10 0 α-relaxation( t α ) correlation time [s] conformational isotropisation (t R/I ) β-relaxation( t β ) αβ-relaxation( t αβ ) / T [K -1 ] NMR PCS Dielectric Arrhenius-diagram of dynamic processes in PEMA

36 Length Scale of Isotropisation Process g T - T from radicalic polymerisation from anionic polymerisation M w = 600 kg mol -1 M w = 15,9 kg mol -1 M w = 7,6 kg mol -1 M w = 1,4 kg mol -1 M w = 0,46 kg mol -1 M w /M n = 1,53 M w /M n = 1,61 M w /M n = 1,48 M w /M n = 1,07 M w /M n = 1,14 * * * 95 K 449 K 434 K 426 K * 403 K 346 K 55 K 410 K 395 K 387 K * * 379 K 322 K * * 300 K 300 K 300 K 278 K 221 K δ [ppm] δ [ppm] δ [ppm] δ [ppm] δ [ppm] 100 M. Wind et al., Macromol. Chem. Phys. 206, 142 (2005).

37 Organisation in Poly(Methacrylats): WAXS Intensity [a.u.] (LVDW) III? (VDW) WAXS-Data II I PMA PBMA II/I d 0 syndiotactic poly(methacrylate) main chain extrapolated lokal structur: "Nano Layers" PEMA d III side chains d II PMMA q [nm -1 ] d I d III Bragg distance d [nm] Bragg distances III (LVDW) I (VDW) number of side chain C atoms II isotactic PEMA side chains main chains M. Wind et al., J. Chem. Phys. 122, (2005).

38 Investigation of Structure and Dynamics in Polymeric Systems via Solid State NMR Introduction Solid State NMR Polymer Dynamics Conclusions Interaction in solid state NMR MAS, recoupling, double-quantum NMR polyelectrolyte layers, polybutadiene, PEMA solid state NMR investigations

39 Pro and Contra of Solid State NMR Investigation double quantum dimension + elucidation local structures in partially disordered systems single quantum dimension + supra-molecular structures in hydrogen bonded systems θ(t 1 ) + local molecular dynamics ω ω θ(t 0 ) θ m + α(t) + correlation of dynamic processes and chemical structure [ppm] ω T = 394 K t c = 3, s [ppm] ω needs expertise expensive -...

40 Acknowledgements Prof. Dr.. W. Spiess ($,, ) Dr. I. Schnell, Dr. K. Saalwächter, Dr. M. Feike, Dr. S. afner, Prof. D. Demco. (NMR) Prof. B. Chmelka, Dr. N. edin (layered silicates) Prof. K. Ishida, Dr. D. Sebastiani (polybenzoxazines) Prof. L. Reven, Dr. M. McCormick (polyelectrolytes) Prof. A. euer (polymer theory, ) Dr. T. Dollase, Dr. M. Neidhöfer (polybutadiene) Dr. M. Wind, Dr. W. Steffen, Prof. Do Yoon (PEMA)