Paper Number
SM37
Session
Polymers Solutions, Melts, and Blends
Title
Polyelectrolytes dynamics and rheology, in a pinch
Presentation Date and Time
October 13, 2021 (Wednesday) 2:45
Track / Room
Track 1 / Ballroom 5
Authors
- Jimenez, Leidy (University of Illinois at Chicago)
- Martínez Narváez, Carina (University of Illinois at Chicago, Chemical Engineering)
- Dinic, Jelena (University of Illinois at Chicago, Department of Chemical Engineering)
- Sharma, Vivek (University of Illinois at Chicago, Chemical Engineering)
Author and Affiliation Lines
Leidy Jimenez, Carina Martínez Narváez, Jelena Dinic and Vivek Sharma
Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607
Speaker / Presenter
Sharma, Vivek
Keywords
experimental methods; theoretical methods; additive manufacturing; applied rheology; biological materials; flow-induced instabilities; non-Newtonian fluids; polymer solutions; rheology methods
Text of Abstract
Biological macromolecules like proteins, DNA, polysaccharides, and many industrial polymers, are classified together as polyelectrolytes. In solution, the repeat units in their backbone are decorated with dissociated, charge-bearing ionic groups, surrounded by a cloud of counter-ions. Even though a large number of polyelectrolytes are processed or used as rheology modifiers in paints, pharmaceuticals, fertilizers, pesticides, and cosmetics, the shear and extensional rheology response of the charged macromolecular solutions is not as well understood as for their uncharged counterparts, and motivate this study. We characterize the pinching dynamics as well as shear and extensional rheology of solutions of three model polyelectrolytes poly(sodium 4-styrene sulfonate) (NaPSS), poly(acrylic acid) (PAA), and sodium carboxymethylcellulose (NaCMC) as a function of solvent and salt concentration. We show that dripping-onto-substrate (DoS) rheometry protocols that involve visualization and analysis of pinching of a columnar neck formed between a nozzle and a sessile drop can be used for measuring extensional viscosity and extensional relaxation time of aqueous polyelectrolyte solutions. We identify universalities in the shear and extensional rheology response of salt-added unentangled semi-dilute solutions and examine the influence of solvent properties on polyelectrolyte dynamics. Unlike shear relaxation time that decreases with an increase in polymer concentration in the unentangled, semidilute salt-free solutions, the measured extensional relaxation time always shows an increase with polymer concentration for the unentangled systems. We elucidate the influence of both electrostatic and hydrodynamic interactions and stretching of macromolecules on stickiness, printability, jettability, and overall processability.