Longitudinal strand ordering leads to shear thinning in Nafion

Michelarakis, Nicholas; Franz, Florian; Gkagkas, Konstantinos; Gräter, Frauke

doi:10.1039/d1cp02024b

Cited by 7 publications

(12 citation statements)

References 92 publications

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“…mainly due to the disentanglement of polymer chain and shear-induced strand alig [24]. The viscosity curve demonstrates good stability of the modified ink over range of shear rates (0.1 to 500 s −1 ), which is suitable for applications in both screen ing and stencil coating.…”

Section: Shear Thinningmentioning

confidence: 90%

“…The sample is highly shear thinning, with a viscosity value at 500 s −1 being around 1778 centipoise (cP), nearly three orders of magnitude smaller than the viscosity value at 0.1 s −1 (1.22 × 10 6 cP). The shear-thinning behavior of modified Nafion is mainly due to the disentanglement of polymer chain and shear-induced strand alignment [24]. The viscosity curve demonstrates good stability of the modified ink over a wide range of shear rates (0.1 to 500 s −1 ), which is suitable for applications in both screen printing and stencil coating.…”

Section: Shear Thinningmentioning

confidence: 92%

“…A slow thixotropic recovery rate may lead to misprints or defects, while a leveling issue could happen if the recovery rate is too fast. The thixotropic property of the modified Nafion ink was characterized by a three-level flow method, similar to the three-interval thixotropy test (3ITT) [22,24]. Viscosities of the samples were measured at three different levels of shear rate for different time periods.…”

Section: Thixotropymentioning

confidence: 99%

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Development of Screen-Printable Nafion Dispersion for Electrochemical Sensor

et al. 2022

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A modified Nafion dispersion for direct screen printing was developed and characterized. Commercial Nafion solution was neutralized to its sodium form and the solvent was replaced by a screen-printing-compatible solvent. The modified Nafion dispersion has optimized rheological properties including shear-thinning behavior, thixotropy, and moderate yield stress. The elemental composition and chemical states of the modified Nafion were characterized by X-ray photoelectron spectroscopy (XPS). The chemical state and composition of the modified Nafion remained the same as those of commercial Nafion. The crystallinity of the cured membranes of both Nafion dispersions was evaluated by X-ray diffraction spectroscopy (XRD). It was found that the modified Nafion has lower crystallinity as compared to the commercial Nafion, and the degree of crystallinity increases with an increase in the curing temperature. The modified material was screen printed onto a commercial sensor as a cation-exchange membrane for the detection of lead Pb(II) in buffer solutions. The sensor showed good linearity in the range of 5 µg/L to 500 µg/L, with a detection limit of 2 µg/L for Pb(II) by square-wave anodic stripping voltammetry. This work demonstrates the possibility of printing Nafion on a large scale in a wide range of fields, such as printed electrochemical sensors.

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Section: Shear Thinningmentioning

confidence: 90%

Section: Shear Thinningmentioning

confidence: 92%

Section: Thixotropymentioning

confidence: 99%

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Development of Screen-Printable Nafion Dispersion for Electrochemical Sensor

et al. 2022

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“…The synovial fluid shows shear thinning, [19][20][21] just as many other industrial or biological systems, from molecular inks and Nafion to cellulose hydrogels, mucus, and blood. [22][23][24][25] Shear thinning is one of the most common types of non-Newtonian behavior of polymers and characterized by a reduction in the viscosity of a fluid shear rate. 26 Non-equilibrium Molecular Dynamics (MD) simulations have previously proven highly useful for studying the response of a polymer solution to shear at the molecular level.…”

Section: Introductionmentioning

confidence: 99%

O-glycans Expand Lubricin and Attenuate its Viscosity and Shear Thinning

Boushehri,

Holey,

Brosz

et al. 2023

Preprint

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Lubricin, an intrinsically disordered glycoprotein, plays a pivotal role in facilitating smooth movement and ensuring the enduring functionality of synovial joints. The central domain of this protein serves as a source of this excellent lubrication, and is characterized by its highly glycosylated, negatively charged, and disordered structure. However, the influence of O-glycans on the viscosity of lubricin remains unclear. In this study, we employ molecular dynamics simulations in absence and presence of shear, along with continuum simulations, to elucidate the intricate interplay between O-glycans and lubricin and the impact of O-glycans on lubricin’s conformational properties and viscosity. We find the presence of O-glycans to induce a more extended conformation in fragments of the disordered region of lubricin. These O-glycans contribute to a reduction in solution viscosity but at the same time weaken shear thinning at high shear rates, compared to non-glycosylated systems with the same density. This effect is attributed to the steric and electrostatic repulsion between the fragments, which prevent their conglomeration and structuring. Our computational study yields a mechanistic mechanism underlying previous experimental observations of lubricin and paves the way to more rationally understanding its function in the synovial fluid.

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“…29 The Martini force field is one of the most commonly applied CG models in the field of biomolecules or materials science. [30][31][32][33] Martini 3 is based on reparameterised small and tiny beads with improved solutesolvent interactions to better reproduce stacking properties, like the bulk density and the oil-water partitioning behavior. 34 The force field offers the advantage of capturing larger spatiotemporal scales of molecular systems while adjusting the level of resolution of their molecular components.…”

Section: Introductionmentioning

confidence: 99%