Underscreening in concentrated electrolytes: re-entrant swelling in polyelectrolyte brushes.

Autor:	Robertson H; College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia. willott.joshua@gmail.com., Elliott GR; College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia. willott.joshua@gmail.com., Nelson ARJ; Australian Centre for Neutron Scattering, ANSTO, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia., Le Brun AP; Australian Centre for Neutron Scattering, ANSTO, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia., Webber GB; College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia. willott.joshua@gmail.com., Prescott SW; School of Chemical Engineering, UNSW Sydney, Sydney, NSW 2052, Australia., Craig VSJ; Department of Materials Physics, Research School of Physics, Australian National University, Canberra, ACT 0200, Australia., Wanless EJ; College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia. willott.joshua@gmail.com., Willott JD; College of Science, Engineering and Environment, University of Newcastle, Callaghan, NSW 2308, Australia. willott.joshua@gmail.com.
Jazyk:	angličtina
Zdroj:	Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2023 Sep 20; Vol. 25 (36), pp. 24770-24782. Date of Electronic Publication: 2023 Sep 20.
DOI:	10.1039/d3cp02206d
Abstrakt:	Hypersaline environments are ubiquitous in nature and are found in myriad technological processes. Recent empirical studies have revealed a significant discrepancy between predicted and observed screening lengths at high salt concentrations, a phenomenon referred to as underscreening. Herein we investigate underscreening using a cationic polyelectrolyte brush as an exemplar. Poly(2-(methacryloyloxy)ethyl)trimethylammonium (PMETAC) brushes were synthesised and their internal structural changes and swelling response was monitored with neutron reflectometry and spectroscopic ellipsometry. Both techniques revealed a monotonic brush collapse as the concentration of symmetric monovalent electrolyte increased. However, a non-monotonic change in brush thickness was observed in all multivalent electrolytes at higher concentrations, known as re-entrant swelling; indicative of underscreening. For all electrolytes, numerical self-consistent field theory predictions align with experimental studies in the low-to-moderate salt concentration regions. Analysis suggests that the classical theory of electrolytes is insufficient to describe the screening lengths observed at high salt concentrations and that the re-entrant polyelectrolyte brush swelling seen herein is consistent with the so-called regular underscreening phenomenon.
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu