Viscosity scaling and entangled solution rheology in aqueous and salt solutions of polyelectrolytes containing diallyl dimethylammonium groups

Helsper, Sedi; Singlar, Nicholas; Garcia, Andrew G.; Liberatore, Matthew W.

doi:10.1007/s00397-023-01428-6

Cited by 3 publications

(2 citation statements)

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“…Membranes were made from solutions containing polyelectrolyte concentrations including 5, 7, 9, and 11 wt % PAAcDMAC in order to study the effects of entanglements on AEM properties. Based on our other studies of the polymer’s rheology, these PAAcDMAC concentrations were above the first critical concentration ( c * ≈1 wt %), i.e., the transition between dilute and semidilute concentration regimes. , AEM casting began at the second critical concentration ( c e ≈ 5 wt %) where the entangled concentration regime begins. For example, the zero-shear rate viscosity increases from 0.2 to 18 Pa-s between 5 and 8 wt % PAAcDMAC at 25 °C, which is an indirect measure of the concentration of entanglements.…”

Section: Resultsmentioning

confidence: 91%

“…For example, the zero-shear rate viscosity increases from 0.2 to 18 Pa-s between 5 and 8 wt % PAAcDMAC at 25 °C, which is an indirect measure of the concentration of entanglements. Thus, these AEMs were cast from solutions in the entangled regime beyond both the dilute and semidilute regimes in hydrochloric acid . Also, AEMs were fabricated at a fixed glutaraldehyde/acrylamide mole ratio of 2:1, drying time of 20 min, and drying temperature of 80 °C.…”

Section: Resultsmentioning

confidence: 99%

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Altering the Mechanical Properties of Scalable, Solvent-Free, Cross-Linked Anion-Exchange Membranes

Asogwa,

Schuld,

Trumbull

et al. 2023

ACS Appl. Polym. Mater.

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Anion-exchange membranes (AEMs) are promising polymer electrolytes for electrochemical energy conversion devices such as fuel cells. In this study, AEMs were fabricated by cross-linking a polyelectrolyte, poly(acrylamide-co-diallyldimethylammonium chloride), with glutaraldehyde using a scalable, organic solvent-free approach based on a recently awarded patent. Successful cross-linking was confirmed through Fourier transform infrared spectroscopy, which showed the formation of C�N bonds in the cross-linked AEMs. The effects of cross-linker-to-polyelectrolyte ratio, polyelectrolyte concentration, drying temperature, and drying time on AEM properties were examined. Changing properties, including water uptake, dimensional swelling, ion-exchange capacity (IEC), conductivity, and mechanical strength under wet and dry conditions, were quantified. Overall, AEMs were about 30 μm in thickness, exhibited dry strength at break up to 33 MPa, and showed chloride conductivity around 100 mS/cm at 80 °C. Increases in crosslinker-to-polyelectrolyte ratio led to decreases in water uptake, swelling, IEC, and ionic conductivity. On the one hand, strength at break and Young's modulus under dry conditions decreased with increasing cross-linkingto-polyelectrolyte ratio. On the other hand, strength at break and Young's modulus under wet conditions increased with increasing cross-linking-to-polyelectrolyte ratio. Next, variations in polyelectrolyte concentrations before casting did not significantly change mechanical or other properties, which disproved the hypothesis that entanglements would enhance mechanical properties. Finally, increases in drying temperature and time did not significantly alter AEM properties above a minimum value.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Altering the Mechanical Properties of Scalable, Solvent-Free, Cross-Linked Anion-Exchange Membranes

Asogwa,

Schuld,

Trumbull

et al. 2023

ACS Appl. Polym. Mater.

Self Cite

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Effect of shear rate, temperature, and salts on the viscosity and viscoelasticity of semi‐dilute and entangled xanthan gum

Kummar,

Dull,

Helsper

et al. 2024

J of Applied Polymer Sci

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Xanthan gum, a naturally‐occurring, high‐molecular‐weight, anionic polyelectrolyte, exhibits significant drag‐reducing properties at low concentrations in water, suggesting promising applications in geothermal networks. The flow behavior of xanthan solutions are explored, specifically at concentrations in the semi‐dilute (1000 ppm by mass) and entangled (4000 ppm) regimes as well as in both water and various salt solutions across a temperature range of 5–85°C. The viscosity and viscoelastic properties of xanthan solutions examine relationships between polyelectrolyte concentration, temperature, and salt concentration. Viscosity decreases by two orders of magnitude in 4000 ppm xanthan solutions in deionized water and with 50 mM NaCl (in the high salt limit) as the temperature increases from 5 to 85°C. Next, the addition of salts affects viscosity differently in the two concentration regimes. Specifically, at 25°C, the zero‐shear rate viscosity upon salt addition decreases by 63% for 1000 ppm solutions (from 0.54 to 0.2 Pa s) but increases by 280% for 4000 ppm solutions (from 28 to 107 Pa s). At 1000 ppm, salt ions cause chain collapse, reducing viscosity; At 4000 ppm, entanglements led to structural changes, resulting in higher viscosity. Furthermore, three salts commonly found in geothermal waters, namely NaCl, Na2CO3, and NaHCO3, exhibited similar changes in viscosity and shear thinning behavior in the entangled regime across temperatures from 5 to 85°C.

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Core–Sheath Fibers via Single-Nozzle Spinneret Electrospinning of Emulsions and Homogeneous Blend Solutions

Kyuchyuk,

Paneva,

Manolova

et al. 2024

Materials

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The preparation of core–sheath fibers by electrospinning is a topic of significant interest for producing composite fibers with distinct core and sheath functionalities. Moreover, in core–sheath fibers, low-molecular-weight substances or nanosized inorganic additives can be deposited in a targeted manner within the core or the sheath. Commonly, for obtaining a core–sheath structure, coaxial electrospinning is used. It requires a coaxial spinneret and suitable immiscible solvents for the inner and outer solutions. The single-nozzle spinneret electrospinning of emulsions can address these issues, but use of a stabilizing agent is needed. A third approach—preparation of core–sheath fibers by single-nozzle spinneret electrospinning of homogeneous blend solutions of two polymers or of a polymer/low-molecular-weight substance—has been much less studied. It circumvents the difficulties associated with the coaxial and the emulsion electrospinning and is thoroughly discussed in this review. The formation of core–sheath fibers in this case is attributed to phase-separation-driven self-organization during the electrospinning process. Some possibilities for obtaining core–double sheath fibers using the same method are also indicated. The gained knowledge on potential applications of core–sheath fibers prepared by single-nozzle spinneret electrospinning of emulsions and homogeneous blend solutions is also discussed.

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Viscosity scaling and entangled solution rheology in aqueous and salt solutions of polyelectrolytes containing diallyl dimethylammonium groups

Cited by 3 publications

References 42 publications

Altering the Mechanical Properties of Scalable, Solvent-Free, Cross-Linked Anion-Exchange Membranes

Altering the Mechanical Properties of Scalable, Solvent-Free, Cross-Linked Anion-Exchange Membranes

Effect of shear rate, temperature, and salts on the viscosity and viscoelasticity of semi‐dilute and entangled xanthan gum

Core–Sheath Fibers via Single-Nozzle Spinneret Electrospinning of Emulsions and Homogeneous Blend Solutions

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