Relaxation times of solid-like polyelectrolyte complexes of varying pH and water content
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2021-09-14
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en
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7765–7776
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Macromolecules, Volume 54, issue 17
Abstract
The effect of complexation pH and water on the relaxation time and dynamics of polyelectrolyte (PE) complexes (PECs) and coacervates remains poorly understood. Here, we describe the dynamic mechanical behavior of solid-like PECs containing weak PEs poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) at varying complexation pH, relative humidity, and temperature with support from molecular dynamics simulations. Time–temperature, time–water, and time–intrinsic ion pair superposition principles are applied to obtain the relaxation times. It is shown that the natural log of relaxation time in hydrated PAH/PAA PECs is inversely proportional to the volume fraction of water (ln τ ∼ φw–1) for a given complexation pH. For all complexation pH values examined, the natural log of relaxation time collapsed into a single line when plotted against the ratio of the number of intrinsic ion pairs to water molecules (ln (τ) ∼ nintrinsic ion pairs/nwater). Taken together, this suggests that the relaxation of solid-like, hydrated PAH/PAA PECs is mediated by bound water at the intrinsic ion pair.Description
This work was supported by the National Science Foundation (grant no. 1905732) (J.L.L.), the National Science Centre, Poland (grant no. 2018/31/D/ST5/01866) (P.B.), and the Academy of Finland (project no. 309324) (M.S.). Computational resources by the PLGrid Infrastructure, Poland, CSC IT Centre for Science, Finland, and RAMI—RawMatTERS Finland Infrastructure are also gratefully acknowledged. M.S. is grateful for the support by the FinnCERES Materials Bioeconomy Ecosystem and use of the Bioeconomy Infrastructure at Aalto.
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Lalwani, S M, Batys, P, Sammalkorpi, M & Lutkenhaus, J L 2021, ' Relaxation times of solid-like polyelectrolyte complexes of varying pH and water content ', Macromolecules, vol. 54, no. 17, pp. 7765–7776 . https://doi.org/10.1021/acs.macromol.1c00940