Polymer- vs. colloidal-type viscoelastic mechanics of microgel pastes


Microgels can form viscoelastic pastes upon packing. For small microgels with low crosslinking density, however, it is unclear if the yielding of these pastes is based on colloid analogous breaking of cages or disentanglement of polymer chain ends at the microgel surface. To answer this question, we investigate pastes of 100-nm-sized poly(N-isopropylacrylamide) pNIPAAm microgels and study the effect of the microgel crosslinking density on the liquid-to-solid transition and the shear-dependent yielding. Our densely crosslinked particles exhibit yield curves with a peak in the loss modulus, typical for shear melting of colloidal crystals due to cage breaking, whereas our microgels with < 10 mol% crosslinker show no loss peak. We conclude that with decreasing crosslinker content, dangling ends and other defects in the microgel polymer network allow for marked interparticle interpenetration, shifting the liquid-to-solid transition to packing fractions > 10 and changing the yielding mechanism from colloid analogous cage breaking to polymer analogous chain disentanglement.

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  1. 1.

    Funke W, Okay O, Joos-Muller B (1998) Microgels—intramolecularly crosslinked macromolecules with a globular structure. Adv Polym Sci 136:139–234

    Article  Google Scholar 

  2. 2.

    Senff H, Richtering W (1999) Temperature sensitive microgel suspensions: colloidal phase behavior and rheology of soft spheres. J Chem Phys 111:1705–1711

    Article  CAS  Google Scholar 

  3. 3.

    Senff H, Richtering W (2000) Influence of cross-link density on rheological properties of temperature-sensitive microgel suspensions. Colloid Polym Sci 278:830–840

    Article  CAS  Google Scholar 

  4. 4.

    Vlassopoulos D, Cloitre M (2014) Tunable rheology of dense soft deformable colloids. Curr Opin Colloid Interface Sci 19:561–574

    Article  CAS  Google Scholar 

  5. 5.

    Mattsson J, Wyss HM, Fernandez-Nieves A, Miyazaki K, Hu Z, Reichmann DR, Weitz DA (2009) Soft colloids make strong glasses. Nature 462:83–86

    Article  CAS  PubMed  Google Scholar 

  6. 6.

    Gasser U, Hyatt JS, Lietor-Santos JJ, Herman ES, Lyon LA, Fernandez-Nieves A (2014) Form factor of pNIPAM microgels in overpacked states. J Chem Phys 034901(1–9):141

    Google Scholar 

  7. 7.

    Fuchs M, Hofacker I, Latz A (1992) Primary relaxation in a hard-sphere system. Phys Rev A 45:898–912

    Article  CAS  PubMed  Google Scholar 

  8. 8.

    vanMegen W, Underwood SM (1994) Glass-transition in colloidal hard spheres—measurement and mode-coupling-theory analysis of the coherent intermediate scattering function. Phys Rev E 49:4206–4220

    Article  CAS  Google Scholar 

  9. 9.

    Pusey PN, vanMegen W (1986) Phase-behavior of concentrated suspensions of nearly hard colloidal spheres. Nature 320:340–342

    Article  CAS  Google Scholar 

  10. 10.

    Pusey PN, vanMegen W (1987) Observation of a glass transition in suspensions of spherical colloidal particles. Phys Rev Lett 59:2083–2086

    Article  CAS  PubMed  Google Scholar 

  11. 11.

    Mohanty PS, Nöjd S, vanGruijtHuijsen K, Crassous JJ, Obiols-Rabasa M, Schweins R, Stradner A, Schurtenberger P (2017) Interpenetration of polymeric microgels at ultrahigh densities. Sci Rep 7:1487 (1–12)

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. 12.

    Yuan Q, Gu J, Zhao Y, Yao L, Guan Y, Zhang Y (2016) Synthesis of a colloidal molecule from soft microgel spheres. ACS Macro Lett 5:565–568

    Article  CAS  Google Scholar 

  13. 13.

    Yao L, Li Q, Guan Y, Zhu XX, Zhang Y (2018) Tetrahedral, octahedral, and triangular dipyramidal microgel clusters with thermosensitivity fabricated from binary colloidal crystals template and thiol−ene reaction. ACS Macro Lett 7:80–84

    Article  CAS  Google Scholar 

  14. 14.

    Daoud M, Cotton JP, Farnoux B, Jannink G, Sarma G, Benoit H, Duplessit R, Picot C, de Gennes PGD (1975) Solutions of flexible polymers. Neutron experiments and interpretation. Macromolecules 8:804–818

    Article  CAS  Google Scholar 

  15. 15.

    Descloizeaux J (1975) Lagrangian theory of polymer-solutions at intermediate concentration. J Phys 36:281–291

    Article  CAS  Google Scholar 

  16. 16.

    Edwards SF (1966) Theory of polymer solutions at intermediate concentration. Proc Phys Soc 88:265–280

    Article  CAS  Google Scholar 

  17. 17.

    Cloitre M, Borrega R, Leibler L (2000) Rheological aging and rejuvenation in microgel pastes. Phys Rev Lett 85:4819–4822

    Article  CAS  PubMed  Google Scholar 

  18. 18.

    Carrier V, Petekidis G (2009) Nonlinear rheology of colloidal glasses of soft thermosensitive microgel particles. J Rheol 53:245–273

    Article  CAS  Google Scholar 

  19. 19.

    Ketz RJ, Prudhomme RK, Graessley WW (1988) Rheology of concentrated microgel solutions. Rheol Acta 27:531–539

    Article  CAS  Google Scholar 

  20. 20.

    Seth JR, Cloitre M, Bonnecaze RT (2008) Influence of short-range forces on wall-slip in microgel pastes. J Rheol 52:1241–1268

    Article  CAS  Google Scholar 

  21. 21.

    Seth JR, Locatelli-Champagne CE, Monti F, Bonnecaze RT, Cloitre M (2012) How do soft particle glasses yield and flow near solid surfaces? Soft Matter 8:140–148

    Article  CAS  Google Scholar 

  22. 22.

    vanderVaart K, Rahmani Y, Zargar R, Hu ZB, Bonn D, Schall P (2013) Rheology of concentrated soft and hard-sphere suspensions. J Rheol 57:1195–1209

    Article  CAS  Google Scholar 

  23. 23.

    Shao Z, Negi AS, Osuji CP (2013) Role of interparticle attraction in the yielding response of microgel suspensions. Soft Matter 9:5492–5500

    Article  CAS  Google Scholar 

  24. 24.

    Urayama K, Saeki T, Cong S, Uratani S, Takigawa T, Murai M, Suzuki D (2014) A simple feature of yielding behavior of highly dense suspensions of soft micro-hydrogel particles. Soft Matter 10:9486–9495

    Article  CAS  PubMed  Google Scholar 

  25. 25.

    Meeker SP, Bonnecaze RT, Cloitre M (2004) Slip and flow in pastes of soft particles: direct observation and rheology. J Rheol 48:1295–1320

    Article  CAS  Google Scholar 

  26. 26.

    Sollich P (1998) Rheological constitutive equation for a model of soft glassy materials. Phys Rev E 58:738–759

    Article  CAS  Google Scholar 

  27. 27.

    Hyun K, Kim SH, Ahn KH, Lee SJ (2002) Large amplitude oscillatory shear as a way to classify the complex fluids. J Non-Newtonian Fluid Mech 107:51–65

    Article  CAS  Google Scholar 

  28. 28.

    Mason T, Weitz D (1995) Linear viscoelasticity of colloidal hard-sphere suspensions near the glass-transition. Phys Rev Lett 75:2770–2773

    Article  CAS  PubMed  Google Scholar 

  29. 29.

    Liu AJ, Nagel SR (1998) Nonlinear dynamics—jamming is not just cool any more. Nature 396:21–22

    Article  CAS  Google Scholar 

  30. 30.

    O’Hern CS, Silbert LE, Liu J, Nagel R (2003) Jamming at zero temperature and zero applied stress: the epitome of disorder. Phys Rev E 011306(1–19):68

    Google Scholar 

  31. 31.

    Biroli G (2007) Jamming—a new kind of phase transition? Nat Phys 3:222–223

    Article  CAS  Google Scholar 

  32. 32.

    vanHecke M (2010) Jamming of soft particles: geometry, mechanics, scaling and isostaticity. J Phys Condens Matter 22:033101 (1–24)

    Article  CAS  Google Scholar 

  33. 33.

    Basu A, Xu Y, Still T, Arratia PE, Zhang Z, Nordstrom KN, Rieser JM, Gollub JP, Durian DJ, AG Y (2014) Rheology of soft colloids across the onset of rigidity: scaling behavior, thermal, and non-thermal responses. Soft Matter 10:3027–3035

    Article  CAS  PubMed  Google Scholar 

  34. 34.

    Ikeda A, Berthier L, Sollich P (2013) Disentangling glass and jamming physics in the rheology of soft materials. Soft Matter 9:7669–7683

    Article  CAS  Google Scholar 

  35. 35.

    Vlassopoulos D, Kapnistos M, Fytas G, Roovers J (2000) Structure and viscoelasticity of interacting spherical brushes. Macromol Symp 158:149–153

    Article  CAS  Google Scholar 

  36. 36.

    Vlassopoulos D (2004) Colloidal star polymers: models for studying dynamically arrested states in soft matter. J Polym Sci Part B Polym Phys 4:2931–2941

    Article  CAS  Google Scholar 

  37. 37.

    Vlassopoulos D, Fytas G (2010) From polymers to colloids: engineering the dynamic properties of hairy particles. Adv Polym Sci 236:1–54

    CAS  Google Scholar 

  38. 38.

    Erwin BM, Cloitre M, Gauthier M, Vlassopoulos D (2010) Dynamics and rheology of colloidal star polymers. Soft Matter 6:2825–2833

    Article  CAS  Google Scholar 

  39. 39.

    Sierra-Martin B, Fernandez-Nieves A (2012) Phase and non-equilibrium behaviour of microgel suspensions as a function of particle stiffness. Soft Matter 8:4141–4150

    Article  CAS  Google Scholar 

  40. 40.

    diLorenzo F, Seiffert S (2015) Counter-effect of Brownian and elastic forces on the liquid-to-solid transition of microgel suspensions. Soft Matter 11:5235–5245

    Article  CAS  Google Scholar 

  41. 41.

    Menut P, Seiffert S, Sprakel J, Weitz DA (2012) Does size matter? Elasticity of compressed suspensions of colloidal- and granular-scale microgels. Soft Matter 8:156–164

    Article  CAS  Google Scholar 

  42. 42.

    Einstein A (1906) Eine neue Bestimmung der Moleküldimensionen. Ann Phys 19:289–306

    Article  CAS  Google Scholar 

  43. 43.

    Kubota K, Fujishige S, Ando I (1990) Solution properties of poly(N-isopropylacrylamide) in water. Polym J 22:15–20

    Article  CAS  Google Scholar 

  44. 44.

    Einstein A (1911) Berichtigung zu meiner Arbeit:“Eine neue Bestimmung der Moleküldimensionen”. Ann Phys 34:591–592

    Article  CAS  Google Scholar 

  45. 45.

    Batchelor GK (1977) Effect of Brownian motion on bulk stress in a suspension of spherical particles. J Fluid Mech 83:97–117

    Article  Google Scholar 

  46. 46.

    diLorenzo F, Seiffert S (2013) Macro- and microrheology of heterogeneous microgel packings. Macromolecules 46:1962–1972

    Article  CAS  Google Scholar 

  47. 47.

    Virtanen OLJ, Ala-Mutka HM, Richtering W (2015) Can the reaction mechanism of radical solution polymerization explain the microgel final particle volume in precipitation polymerization of N-isopropylacrylamide? Macromol Chem Phys 216:1431–1440

    Article  CAS  Google Scholar 

  48. 48.

    Stieger M, Pedersen JS, Lindner P, Richtering W (2004) Are thermoresponsive microgels model systems for concentrated colloidal suspensions? A rheology and small-angle neutron scattering study. Langmuir 20:7283–7292

    Article  CAS  PubMed  Google Scholar 

  49. 49.

    Heo Y, Larson RG (2008) Universal scaling of linear and nonlinear rheological properties of semidilute and concentrated polymer solutions. Macromolecules 41:8903–8915

    Article  CAS  Google Scholar 

  50. 50.

    Antonietti M, Bremser W, Schmidt M (1990) Microgels—model polymers for the crosslinked state. Macromolecules 23:3796–3805

    Article  CAS  Google Scholar 

  51. 51.

    Gao J, Hu Z (2002) Optical properties of N-isopropylacrylamide microgel spheres in water. Langmuir 18:1360–1367

    Article  CAS  Google Scholar 

  52. 52.

    Wu C (1998) A comparison between the ‘coil-to-globule’ transition of linear chains and the “volume phase transition” of spherical microgels. Polymer 19:4609–4619

    Article  Google Scholar 

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We thank Dr. K. Fischer for performing static and dynamic light scattering measurements to determine the ρ ratio for our soft microgels of crosslinker content 1.33 mol% (sample M75).

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Correspondence to Wolfgang Schärtl or Sebastian Seiffert.

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Kunz, S., Pawlik, M., Schärtl, W. et al. Polymer- vs. colloidal-type viscoelastic mechanics of microgel pastes. Colloid Polym Sci 296, 1341–1352 (2018). https://doi.org/10.1007/s00396-018-4352-5

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  • Colloids
  • Microgels
  • Rheological properties
  • Viscoelasticity