Nonlinear rheology and dynamics of supramolecular polymer networks formed by associative telechelic chains under shear and extensional flows

Amin, Dipesh; Wang, Zuowei

doi:10.1122/1.5120897

Cited by 35 publications

(28 citation statements)

References 84 publications

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“…Similar mild shear thickening, reported before for aqueous solutions of multisticker associative polymers, including hmHEC, , was attributed to the shear-induced structuring of the transient network. Considerably more studies have probed shear thickening in telechelic associative polymers and attributed the mild increase in viscosity to the influence of the creation–destruction rate of hydrophobic associations and chain stretching and orientation in response to applied deformation fields. − The absolute enhancement in viscosity due to shear thickening (see Figure b) is relatively low in magnitude (note the ordinate values are on a linear scale) compared to the orders of magnitude change for particle suspensions. ,, Furthermore, as the mild thickening is manifested only for 0.4 < c < 1.0 wt. % hmHEC solutions, the Cross model provides a pragmatic description of rate-dependent viscosity illustrated in Figure b.…”

Section: Resultsmentioning

confidence: 99%

Rheology and Pinching Dynamics of Associative Polysaccharide Solutions

Narváez

Dinic

et al. 2021

Macromolecules

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Associative polysaccharides, decorated by multiple but short, side-chain hydrophobic stickers (typically 6–20 carbon long) that associate in solution, are used as thickeners for an extensive range of aqueous-based formulations. Characterizing and elucidating the influence of stickers on the response to extensional flows that spontaneously arise in pinching necks formed during spraying, jetting, or coating fluids have remained longstanding experimental and analytical challenges due to relatively low viscosity and elasticity of industrially relevant systems. In this contribution, we contrast the shear rheology as well as extensional rheology and pinching dynamics of hydrophobically modified hydroxyethyl cellulose (hmHEC, M w = 300 kg/mol) as a sticky polymer with the bare chain of a higher molecular weight (hydroxyethyl cellulose (HEC), M w = 720 kg/mol) using the recently developed dripping-onto-substrate (DoS) rheometry protocols. We show that sticker associations enhance zero shear viscosity and relaxation time (elasticity), and both quantities display stronger concentration-dependent variation for sticky polymers. Striking differences are observed in neck shapes, radius evolution profiles, and extensional viscosity plotted as a function of strain as well as strain rate. We present a comprehensive analysis of changes in pinching dynamics, concentration-dependent variation in steady, terminal viscosity as well as filament lifespan as a function of the sticky polymer concentration and describe the influence of multiple stickers on the macromolecular strain, relaxation, and dynamics of associative polysaccharides.

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Section: Resultsmentioning

confidence: 99%

Rheology and Pinching Dynamics of Associative Polysaccharide Solutions

Narváez

Dinic

et al. 2021

Macromolecules

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“…The stickers aggregate to form physical cross-links that improve the mechanical properties and add functionality to the base polymer, − which makes them suitable for a variety of applications, including membranes, compatibilizers, shape memory, and self-healing . Neat ionomers, however, usually exhibit low stretchability when rapidly deformed due to strain-induced dissociation of the ionic groups, and as a result, they often exhibit brittle, macroscopic fractures. − The macroscopic ductility of the associative polymer materials generally relies on the following: (1) microscopic stretchability of the stress-bearing network strands and (2) energy dissipation and structural rearrangements of the stickers when strain-induced breakup occurs. − …”

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Brittle-to-Ductile Transition of Sulfonated Polystyrene Ionomers

et al. 2021

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This study examines the brittle-to-ductile transition of sulfonated polystyrene ionomers (SPS) with different counterions. The polystyrene precursor was unentangled and had two ionic groups per chain on average. Thus, its terminal relaxation time was comparable to the lifetime of the associating ionic groups. Three types of ionomer samples were used to tune the association lifetime: (1) fully neutralized SPS with different alkali-metal counterions, (2) fully neutralized SPS with mixed sodium and cesium counterions, and (3) partially neutralized SPS with sodium or cesium counterions. For all three systems, the brittle-to-ductile transition could be represented by a diagram of two Weissenberg numbers, Wi and Wi R, defined with respect to the terminal and Rouse relaxation times, respectively. A flowable region existed at sufficiently low Wi, independent of Wi R. At higher Wi, a brittle-to-ductile transition of the ionomer melt occurred above a critical value of Wi R. To achieve ductility during the application of rapid elongational flow, the Rouse-type motions should be sufficiently slow relative to the rate of ion-dissociation, so that the strain-induced breakup of the ionic cross-links would not cause very strong chain retraction that may further lead to the macroscopic fracture.

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“…It is a well-established strategy to tailor rheological properties of polymeric materials through incorporating associative groups as “stickers”. − For random associative polymers, rich rheological properties stem from variations of density, position, and strength of the stickers.…”

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Using Coupling Motion of Connecting Ions in Designing Telechelic Ionomers

2020

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Conventional telechelic ionomers have one ion fixed at each end, enabling the chains to form a physical network. Here we report a type of telechelic ionomers with a distribution of the number of ions at the chain ends, which endows them with very rich rheological properties. We synthesized the ionomer samples via a two-step polymerization. Namely, we synthesized a precursor chain first and then polymerized a few ion-containing monomers at its two ends. An average number of ion-containing monomers per chain end, m, varies from 0 to 3.0. Linear viscoelasticity of these samples can be well explained through considering the Poisson distribution of m, and the hierarchical relaxation of the chains ends according to the number of connecting ions that exhibit the coupling motion.

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Nonlinear rheology and dynamics of supramolecular polymer networks formed by associative telechelic chains under shear and extensional flows

Abstract: Z. (2020) Nonlinear rheology and dynamics of supramolecular polymer networks formed by associative telechelic chains under shear and extensional flows.

Cited by 35 publications

References 84 publications

Rheology and Pinching Dynamics of Associative Polysaccharide Solutions

Rheology and Pinching Dynamics of Associative Polysaccharide Solutions

Brittle-to-Ductile Transition of Sulfonated Polystyrene Ionomers

Using Coupling Motion of Connecting Ions in Designing Telechelic Ionomers

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