Nonadditive Ion Effects Drive Both Collapse and Swelling of Thermoresponsive Polymers in Water.

When a mixture of two salts in an aqueous solution contains a weakly and a strongly hydrated anion, their combined effect is nonadditive. Herein, we report such nonadditive effects on the lower critical solution temperature (LCST) of poly( N-isopropylacrylamide) (PNiPAM) for a fixed concentration of Na2SO4 and an increasing concentration of NaI. Using molecular dynamics simulations and vibrational sum frequency spectroscopy, we demonstrate that at low concentrations of the weakly hydrated anion (I-), the cations (Na+) preferentially partition to the counterion cloud around the strongly hydrated anion (SO42-), leaving I- more hydrated. However, upon further increase in the NaI concentration, this weakly hydrated anion is forced out of solution to the polymer/water interface by sulfate. Thus, the LCST behavior of PNiPAM involves competing roles for ion hydration and polymer-iodide interactions. This concept can be generally applied to mixtures containing both a strongly and a weakly hydrated anion from the Hofmeister series.

• Publication year

  2019

• Venue

  Journal of the American Chemical Society

• Publication date

  2019-03-28

• Fields of study

  Medicine, Materials Science, Chemistry

• Identifiers
  DOI 10.1021/jacs.9b00295PMID 30919630
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar, PubMed

• No claims are published for this paper.

• No concepts are published for this paper.

• Guanidinium can both Cause and Prevent the Hydrophobic Collapse of Biomacromolecules

  2017cited by this paper
• The Hydrophobic Effect and the Role of Cosolvents.

  2017cited by this paper
• Anionic and cationic Hofmeister effects are non-additive for guanidinium salts.

  2017cited by this paper
• Water-Mediated Ion Pairing: Occurrence and Relevance.

  2016cited by this paper
• Hofmeister effect of salt mixtures on thermo-responsive poly(propylene oxide).

  2015cited by this paper
• An NH moiety is not required for anion binding to amides in aqueous solution.

  2015cited by this paper
• Beyond Hofmeister.

  2014cited by this paper
• Ion-pair or Ion-cloud Relaxation? On the Origin of Small-amplitude Low-frequency Relaxations of Weakly Associating Aqueous Electrolytes

  2012cited by this paper
• Hofmeister phenomena: an update on ion specificity in biology.

  2012cited by this paper
• Arginine and the Hofmeister Series: the role of ion-ion interactions in protein aggregation suppression.

  2011cited by this paper
• The influence of concentration on the molecular surface structure of simple and mixed aqueous electrolytes.

  2010cited by this paper
• Cation specific binding with protein surface charges

  2009cited by this paper
• Variation of Ionic Strength Reveals the Interfacial Water Structure at a Charged Mineral Surface

  2009cited by this paper
• Effects of Hofmeister anions on the phase transition temperature of elastin-like polypeptides.

  2008cited by this paper
• Thermodynamic origin of hofmeister ion effects.

  2008cited by this paper
• Specific ion effects on interfacial water structure near macromolecules.

  2007cited by this paper
• Hofmeister salt effects on surface tension arise from partitioning of anions and cations between bulk water and the air-water interface.

  2007cited by this paper
• Modeling Solution Phase Behavior in Multicomponent Ion Exchange Equilibria Involving H+, Na+, K+, Mg2+, and Ca2+ Ions

  2005cited by this paper
• Specific ion effects on the water solubility of macromolecules: PNIPAM and the Hofmeister series.

  2005cited by this paper
• Is there an anionic Hofmeister effect on water dynamics? Dielectric spectroscopy of aqueous solutions of NaBr, NaI, NaNO3, NaClO4, and NaSCN.

  2005cited by this paper
• ‘Zur Lehre von der Wirkung der Salze’ (about the science of the effect of salts): Franz Hofmeister's historical papers

  2004cited by this paper
• Molecular bonding and interactions at aqueous surfaces as probed by vibrational sum frequency spectroscopy.

  2002cited by this paper
• Investigations of Lysozyme Adsorption at the Air/Water and Quartz/Water Interfaces by Vibrational Sum Frequency Spectroscopy

  2002cited by this paper
• Molecular Structure of Salt Solutions: A New View of the Interface with Implications for Heterogeneous Atmospheric Chemistry

  2001cited by this paper
• ION-PAIR AND SOLVENT RELAXATION PROCESSES IN AQUEOUS NA2SO4 SOLUTIONS

  1999cited by this paper
• Correlations and Thermodynamic Coefficients in Dilute Asymmetric Electrolyte Solutions

  1996cited by this paper
• Vibrational spectra of water molecules at quartz/water interfaces.

  1994cited by this paper
• The Hofmeister effect and the behaviour of water at interfaces

  1985cited by this paper
• Electrical double layer forces: a Monte Carlo study

  1984cited by this paper
• The bromide/chlorinity and sulphate/chlorinity ratio in sea water

  1966cited by this paper
• Specific interaction of ions

  1955cited by this paper
• L. The specific thermodynamic properties of aqueous solutions of strong electrolytes

  1935cited by this paper
• THE INDIVIDUAL THERMODYNAMIC PROPERTIES OF IONS

  1923cited by this paper
• STUDIES ON SOLUBILITY. IV. THE PRINCIPLE OF THE SPECIFIC INTERACTION OF IONS

  1922cited by this paper
• Zur Lehre von der Wirkung der Salze

  1888cited by this paper

• Ion coordination competition enhanced adsorption strategy for improved thermopower in I−/I3− gel-based thermo-electrochemical cells

  2026cites this paper
• Beyond Electrostatic Screening: Effect of Ion Pairing on Acid-Base Equilibria in Complex Electrolyte Solutions.

  2026cites this paper
• Anions-Impacted Water Purification from a Dual-Substrate Perspective.

  2025cites this paper
• Ion-Specific Control over Transparency Transition and Mechanical Properties of Dual Thermoresponsive Hydrogels.

  2025cites this paper
• Understanding the Lower Critical Solution Temperature of amphiphilic synthetic polymers in water: the role of conformation and hydration

  2025cites this paper
• Determination of aqueous solubility of NaCl in molecular dynamics simulation using the Kirkwood-Buff method.

  2025cites this paper
• ATP Can Act as a Stabilizer on Neutral Macromolecules

  2025cites this paper
• Anion Competition at Positively Charged Surfactant Monolayers.

  2024cites this paper
• Interactions between the protein barnase and co-solutes studied by NMR

  2024cites this paper
• Stimuli-triggered multilayer films in response to temperature and ionic strength changes for controlled favipiravir drug release

  2024cites this paper
• Synergistic Assembly of Charged Oligomers and Amino Acids at the Air-Water Interface: An Avenue toward Surface-Directed CO2 Capture.

  2024cites this paper
• Solvation Dynamics of Thermoresponsive Polymer Films: The Influence of Salt Series in Water and Mixed Water/Methanol Atmosphere

  2024cites this paper
• The inductive effect does not explain electron density in haloacetates: are our textbooks wrong?

  2024cites this paper
• Competitive Effects of Anions on Protein Solvation by Aqueous Ionic Liquids

  2024cites this paper
• Salt-specific effect on the solubility and aggregation of 1-butanol in water

  2024cites this paper
• Ionic Effect on the Microenvironment of Biomolecular Condensates.

  2024cites this paper
• Exploring the Effects and Interactions of Conducting Polymers in the Volume Phase Transition of Thermosensitive Conducting Hydrogels

  2024cites this paper
• Water model determines thermosensitive and physicochemical properties of poly(N-isopropylacrylamide) in molecular simulations

  2023cites this paper
• Visualizing Water Monomers and Chiral OH-(H2O) Complexes Infiltrated in a Macroscopic Hydrophobic Teflon Matrix.

  2023cites this paper
• Solvation Behavior of Elastin-like Polypeptides in Divalent Metal Salt Solutions.

  2023cites this paper
• Anions and Cations Affect Amino Acid Dissociation Equilibria via Distinct Mechanisms.

  2023cites this paper
• Ions Speciation at the Water–Air Interface

  2023cites this paper
• Effect of Magnesium Salts with Chaotropic Anions on the Swelling Behavior of PNIPMAM Thin Films

  2023cites this paper
• Ion-specific binding of cations to the carboxylate and of anions to the amide of alanylalanine

  2022cites this paper
• Micellar shuttle of a polymeric ionic liquid (P(EHO)-CI-P(EtOx)) in a water/ethyl acetate two-phase system: Micellar load capacity and selective transfer of molecular anions

  2022cites this paper
• Cononsolvency of thermoresponsive polymers: where we are now and where we are going.

  2022cites this paper
• How Temperature Rise Can Induce Phase Separation in Aqueous Biphasic Solutions.

  2022cites this paper
• Nonadditive ion effects on the coil-globule equilibrium of PNIPAM: a computer simulation study.

  2022cites this paper
• Nanopore Sensing Technique for Studying the Hofmeister Effect.

  2022cites this paper
• Counter ion effect on α-Keggin polyoxometalates in water: the peculiar role of H+ on their salting-in effect and co-assembly with organics

  2022cites this paper
• A simple theory for interfacial properties of dilute solutions.

  2022cites this paper
• Understanding specific ion effects and the Hofmeister series.

  2022cites this paper
• Design of hydrogel-microgel composites with tailored small molecule release profiles.

  2022cites this paper
• DFT study of common anions adsorption at graphene surface due to anion-π interaction

  2022cites this paper
• The influence of cross-interactions between dilute cosolutes upon liquid interfaces.

  2022cites this paper
• The direction of influence of specific ion effects on a pH and temperature responsive copolymer brush is dependent on polymer charge

  2021cites this paper
• An interplay of excluded-volume and polymer-(co)solvent attractive interactions regulates polymer collapse in mixed solvents.

  2021cites this paper
• Intramolecular hydrogen bonds in a single macromolecule: Strength in high vacuum versus liquid environments

  2021cites this paper
• Molecular bases for temperature sensitivity in supramolecular assemblies and their applications as thermoresponsive soft materials.

  2021cites this paper
• Cation Identity Affects Nonadditivity in Salt Mixtures Containing Iodide and Sulfate

  2021cites this paper
• Modeling of Peptides with Classical and Novel Machine Learning Force Fields: A Comparison.

  2021cites this paper
• Specific Ion–Protein Interactions Influence Bacterial Ice Nucleation

  2021cites this paper
• Contact Ion Pairs in the Bulk Affect Anion Interactions with Poly(N-isopropylacrylamide).

  2021cites this paper
• Competitive specific ion effects in mixed salt solutions on a thermoresponsive polymer brush.

  2020cites this paper
• A cosolvent surfactant mechanism affects polymer collapse in miscible good solvents

  2020cites this paper
• The role of carboxyl groups upon the precipitation of albumin at low pH

  2020cites this paper
• Hofmeister Effect in Self-Organized Chemical Systems.

  2020cites this paper
• Rapid quantification of the malaria biomarker hemozoin by improved biocatalytically initiated precipitation atom transfer radical polymerizations.

  2020cites this paper
• Counteranions in the Stimulation Solution Alter the Dynamics of Exocytosis Consistent with the Hofmeister Series

  2020cites this paper
• Poly(N,N-bis(2-methoxyethyl)acrylamide), a thermoresponsive non-ionic polymer combining the amide and the ethyleneglycolether motifs

  2020cites this paper
• A novel thermo-responsive system based on β-cyclodextrin-nanocomposite for improving the docetaxel activity

  2020cites this paper
• Ionic effects on synthetic polymers: from solutions to brushes and gels.

  2020cites this paper
• Temperature-Responsive Multilayer Films of Micelle-Based Composites for Controlled Release of a Third-Generation EGFR Inhibitor

  2020cites this paper
• Thermal Behaviour of Common Thermoresponsive Polymers in Phosphate Buffer and in Its Salt Solutions

  2020cites this paper
• Reversed Anionic Hofmeister Effect in Metal-Phenolic-Based Film Formation.

  2020cites this paper
• Poly(N-isopropylacrylamide)-grafted gold nanoparticles at the vapor/water interface.

  2020cites this paper
• Probing the response of poly (N-isopropylacrylamide) microgels to solutions of various salts using etalons.

  2020cites this paper
• Coil-Globule Transition Thermodynamics of Poly(N-isopropylacrylamide).

  2019cites this paper
• The Hofmeister series: Specific ion effects in aqueous polymer solutions.

  2019cites this paper
• Specific Ion Effects of Dodecyl Sulfate Surfactants with Alkali Ions at the Air–Water Interface

  2019cites this paper
• Molecular Scale Solvation in Complex Solutions.

  2019cites this paper
• Common Source of Cryoprotection and Osmoprotection by Osmolytes.

  2019cites this paper