Irreversible Shear-Activated Gelation of a Liquid Crystalline Polyelectrolyte

Ryan J. Fox, Maruti Hegde, Curt J. Zanelotti, Amar S. Kumbhar, Edward T. Samulski, Louis A. Madsen, Stephen J. Picken, Theo J. Dingemans

Research output: Contribution to journalArticleScientificpeer-review

Abstract

We report irreversible, shear-activated gelation in liquid crystalline solutions of a rigid polyelectrolyte that forms rodlike assemblies (rods) in salt-free solution. At rest, the liquid crystalline solutions are kinetically stable against gelation and exhibit low viscosities. Under steady shear at, or above, a critical shear rate, a physically cross-linked, nematic gel network forms due to linear growth and branching of the rods. Above a critical shear rate, the time scale of gelation can be tuned from hours to nearly instantaneously by varying the shear rate and solution concentration. The shear-activated gels are distinct in their structure and rheological properties from thermoreversible gels. At a fixed concentration, the induction time prior to gelation decreases exponentially with the shear rate. This result indicates that shear-activated thermalization of the electrostatically stabilized rods overcomes the energy barrier for rod-rod contact, enabling rod fusion and subsequent irreversible network formation.

Original languageEnglish
Pages (from-to)957-963
JournalACS Macro Letters
Volume9
Issue number7
DOIs
Publication statusPublished - 2020

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    Fox, R. J., Hegde, M., Zanelotti, C. J., Kumbhar, A. S., Samulski, E. T., Madsen, L. A., Picken, S. J., & Dingemans, T. J. (2020). Irreversible Shear-Activated Gelation of a Liquid Crystalline Polyelectrolyte. ACS Macro Letters, 9(7), 957-963. https://doi.org/10.1021/acsmacrolett.0c00168