Rheology of complex macromolecules: Relating their composition to their viscoelastic properties

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1 Rheology of complex macromolecules: Relating their composition to their viscoelastic properties Evelyne van Ruymbeke Bio and Soft Matter Université catholique de Louvain, Belgium May 18, Gent

2 Structure - LVE relationship for complex polymers: Direct Inverse Tailored polymers Molecular structure Linear regime Modeling: Working on model polymers Flow properties polydisperse polymers Sample characterization Supramolecular polymers 2

3 Tube model At the mesoscopic scale Tube-based model for predicting the LVE of complex polymer melts de Gennes, Doi and Edwards 3

Equilibrium state t Equilibrium state: M e,0, τ e Doi

4 Relaxation modulus of a polymer Relaxation modulus: Rouse process: N G 0 G(t) Glassy region Rouse process Equilibrium state t Equilibrium state: M e,0, τ e Doi & Edwards (1967), de Gennes (1971) G N 0 = 4 ρrt 5 M e 4

5 Equilibrium state: Tube picture Tube picture M e,0 τ e Doi & Edwards (1967), de Gennes (1971) 5

6 Relaxation modulus of a polymer Reptation process Diffusion process along the curvilinear axis of the tube 6

7 Relaxation modulus of a polymer Contour length Fluctuations: 7

8 Relaxation modulus of a polymer Arm retraction: Process entropically unfavorable Long relaxation times 8 Milner, McLeish 1997

9 Constraint Release processes (CR) 9

10 Constraint Release processes (CR) 10

11 Constraint Release processes (CR) 11

$fraction already relaxed =$

12 Constraint Release processes (CR) Dynamic tube dilation: The polymer fraction already relaxed = solvent 12

13 Relaxation modulus of a polymer N G 0 G(t) Glassy region Rouse process Equilibrium state t G'(ω) [Pa] PBD20k PBD550k ω [rad/s] 13

14 Constraint Release processes (CR) Dynamic tube dilation: Local effect On the reptation and the fluctuations process: x=1 x=1/3 x=0 x=1/3 L eq,0 L eq (t) Speeds up the polymer relaxation Inter-relationship between all the relaxation mechanisms Marrucci,

15 Structure - LVE relationship for complex polymers: Model architectures: Linear chains symmetric star 15

16 Structure - LVE relationship for complex polymers: G,G (ω) Hierarchy of relaxation processes oo: Experimental data, --: Predictions ω [rad/s] E. van Ruymbeke, R. Keunings, C. Bailly, J.N.N.F.M., 2005 E. van Ruymbeke, C. Bailly, R. Keunings, D. Vlassopoulos, Macromolecules, M. Ahmadi, C. Bailly, R. Keunings, M. Nekoomanesh, E. van Ruymbeke, Macromolecules,

17 Objectives LVE of Models branched polymers Rheology polydisperse samples symmetric star Linear chains Asymmetric star H polymer Pompom polymer Rheology as characterization tool for industrial samples Rheology of entangled associating polymers 17

18 Unentangled versus entangled supramolecular building bocks - Short blocks - Polymer solution + metal + metal G(t) Elastic reversible network G(t) Elastic reversible network Liquid-like behavior t Viscoelastic building blocks t 18

19 Unentangled versus entangled supramolecular building bocks - Short blocks - Polymer solution + metal Rubbery plateau and relaxation time: + metal Depend on both supramolecular dynamics and chain architecture G(t) Elastic reversible network G(t) Elastic reversible network Liquid-like behavior t Viscoelastic building blocks t

20 Dynamics of sticky entangled polymer melts : sticker : entanglement Two elastic plateaus Slow decrease of G Hydrolyzed PnBA G',G"(ω) [Pa] TPE 5 w% HB ω [rad/s]

21 PnBA: Poly (n-butyl acrylate) Hydrolyzed PnBA polymers Hydrolysis Basic environment Two elastic plateaus M w =210kg/mol Goldansaz et al., Macromol

22 Temperature effect: Hydrolyzed PnBA polymers 10 7 sample G,G (ω) a T ω - The second plateau disappears with increasing T - Thermo-rheological complexity governed by the association dynamics Lifetime (sticker) > Lifetime (entanglement) 22

23 Trapped segments versus dangling ends: p st, the probability to find an associated sticker Acrylic acid aggregates, Star-like molecules Trapped chains Free linear chains dangling ends of trapped chains test chain Only the trapped chains cannot relax Hawke et al., JOR

24 Molecular picture: related rheology Loss and storage modulus (Pa) Zone 4: zone 4 Supramolecul lower plateau zone ar network only trapped strands between sticky junctions contribute to elasticity Zone zone 3 3: CRR process Constraint Release Rouse (CR) equilibration of the trapped strands Zone 2: Rubbery plateau Relaxation of mobile phase zone 2 upper plateau zone-both entanglements and trapped strands contribute to elasticity mobile components gradually start to relax orientation zone 1 Zone 1: high frequency Rouse regime Rouse regime M e, total Angular Frequency (rad/s) Hawke et al., JOR 2016 M e,

25 Comparison to experimental data 10 7 T=-35 o C, -15 o C, -5 o C 10 6 T=25 o C 10 6 T=45 o C G',G"(ω) [Pa] p st =1/1500 p st =1/1550 p st =1/ ω [rad/s] T=65 o C 10 6 T=85 o C 10 6 T=105 o C G',G"(ω) [Pa] p st =1/ p st =1/ p st =1/ ω [rad/s] ω [rad/s] ω [rad/s] 25

26 Comparison to experimental data Exponential decay of p st : Delay in the first transition: 26

27 Dynamics of sticky entangled polymer melts Two elastic plateaus Slow decrease of G Hydrolyzed PnBA G',G"(ω) [Pa] TPE 5 w% HB ω [rad/s]

28 Thermoplastic elastomers: TPEs PTHF T4T PTHF T4T PTHF G',G"(ω) [Pa] T 5w% Connected with supramolecular bonds (H bond type) and by crystallization A = soft block B = hard block ω [rad/s] The stickers can dissociate and associate again Samples: A. Sharma, W. Appel, DSM (Geleen, The Netherlands) 28

29 Flory distribution TPE 5% HB M n, strand = 6840 g/mol M n, chain = g/mol p end = 2.85/1000 p sticker = 7.7/1000 x x x dw(m)/dlog(m) M w [g/mol] x MWD (chains) 29

30 Assumptions: Accounting for sticky groups in tube model - Statistical distribution of the stickers - A sticker can be associated, or not: p st - Fluctuations process of a segment x only takes place if there is no active sticker between the chain extremity and x This segment cannot relax by CLF : active sticker : unassociated sticker This segment can relax by CLF : active sticker : unassociated sticker Penalty on the time during which a chain is relaxing 30

31 Accounting for sticky groups in tube model Input data: - Flory distribution with Mn=25.2 kg/mol - p sticker = 7.7/1000 (active or not) - p st = prob (a sticker is active) G',G"(ω) [Pa] TPE 5 w% HB T ω [rad/s] G ',G "(ω ) [P a] p st ω [rad/s]

32 Conclusions - By using statistical tool, we can often have a good representation of branched or sticky polymers. - The rheological behavior of sticky entangled polymers strongly depends on the balance between association and entanglement dynamics. - Based on tube models, one can rationalize their relaxation process. - (Rheology + model) gives us a powerful characterization tool. 32

Acknowledgment UCL colleagues: Quentin Voleppe Ashinikumar Sharma Hadi Goldansaz Laurence Hawke Charles-André Fustin Jean Francois Gohy Christian Bailly Collaborators: Dimitris Vlassopoulos (FORTH,

33 Acknowledgment UCL colleagues: Quentin Voleppe Ashinikumar Sharma Hadi Goldansaz Laurence Hawke Charles-André Fustin Jean Francois Gohy Christian Bailly Collaborators: Dimitris Vlassopoulos (FORTH, Heraklion) Nikos Hadjichristidis (KAUST) Hiroshi Watanabe (Univ. of Kyoto) Salvatore Coppola (Polymeri Europa, Bologna) Paul Steeman, Han Slot, W. Appel (DSM, Geleen) Taihyun Chang (Corea) This work has been supported by the F.N.R.S. Communauté Francaise de Belgique. Thank you! 33

34 34

35 Assumptions: Association dynamics of the stickers: - p free = prob (a sticker is not active) - After a time t, a sticker was free during This assumption is valid only at long times t 35

Part III. Polymer Dynamics molecular models

Part III. Polymer Dynamics molecular models I. Unentangled polymer dynamics I.1 Diffusion of a small colloidal particle I.2 Diffusion of an unentangled polymer chain II. Entangled polymer dynamics II.1.