Paper Number
SM38 

Session
Polymers Solutions, Melts, and Blends

Title
Dynamic signatures of gelation in associative polymer solutions

Presentation Date and Time
October 13, 2021 (Wednesday) 3:45

Track / Room
Track 1 / Ballroom 5

Authors (Click on name to view author profile)

1. Santra, Aritra (Monash University, Department of Chemical Engineering)
2. McKinley, Gareth H. (Massachusetts Institute of Technology, Mechanical Engineering)
3. Prakash, J. Ravi (Monash University, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Aritra Santra¹, Gareth H. McKinley² and J. Ravi Prakash^1
1Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia; ²Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA

Speaker / Presenter 
Santra, Aritra

Keywords
computational methods; gels; polymer solutions

Text of Abstract
Solutions of associative polymers form reversible gels at moderately low concentration by physical cross-linking of sticky groups distributed along the chain backbones. While at least three different static signatures of gelation, such as the percolation transition, the maxima in the free-chain concentration and the occurrence of bimodality in the cluster-size distribution have been identified in these systems [1], the relationship between these static measures and the dynamic response of associative polymer solutions close to the gel point remains unresolved. The formation of intricate topologies leads to the existence of complex relaxation behaviour. In this work, multi-chain Brownian dynamics simulations with hydrodynamic interactions incorporated, have been carried out to examine the dynamic and linear viscoelastic behaviour of multi-sticker associative polymer solutions at finite concentrations and the various static and dynamic gelation signatures have been studied. Equilibrium and shear flow simulations have been performed to compute the zero-shear rate viscosity and storage and loss moduli. It is found that the zero-shear rate viscosity and a variety of different characteristic relaxation times exhibit a cross-over in their scaling behaviour with monomer concentration close to the location of the maxima in free chain concentration. The influence of the time scales associated with the binding and unbinding of stickers on the overall relaxation behaviour has also been explored. Finally, simulation results are compared with the predictions of the sticky Rouse model proposed by Rubinstein and Semenov [2,3], in the relevant regimes, and excellent agreement is observed.

[1] A. Santra, B. Duenweg, and J. R. Prakash, J. Rheol., 65, 549-581, 2021.
[2] M. Rubinstein, A. N. Semenov, Macromolecules, 31, 1386-1397, 1998.
[3] M. Rubinstein, A. N. Semenov, Macromolecules, 34, 1058-1068, 2001.