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 1 publication

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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%