Enhanced specific ion effects in ethylene glycol-based thermoresponsive polymer brushes

Murdoch, Timothy J.; Humphreys, Ben A.; Willott, Joshua D.; Prescott, Stuart W.; Nelson, Andrew; Webber, Grant B.; Wanless, Erica J.

doi:10.1016/j.jcis.2016.11.044

Cited by 34 publications

(74 citation statements)

References 60 publications

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“…In one study, they demonstrated that the average thickness of an ethylene glycol-based polymer brush in the presence of 500 mM NaSCN is approximately twice that observed in a salt-free solution (Figure 7c) [202]. The Debye screening length for such a high salt concentration is ~0.4 nm, suggesting the unlikelihood of such a drastic swelling solely due to electrostatic repulsions; however, it could be reasoned based on the osmotic effect.…”

Section: Accumulation At the Polymer Surface: What Are The Sources Of Stabilization?mentioning

confidence: 97%

“…Such an osmotic effect might also explain the observed conformational swelling of neutral polymers in the presence of weakly hydrated salts. For example, Wanless et al investigated the effect of salts on polymer brush films in terms of the polymer film thickness and density profiles [202,208,209].…”

Section: Accumulation At the Polymer Surface: What Are The Sources Of Stabilization?mentioning

confidence: 99%

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The Hofmeister series: Specific ion effects in aqueous polymer solutions

Moghaddam

Thormann

2019

Journal of Colloid and Interface Science

132

116

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Section: Accumulation At the Polymer Surface: What Are The Sources Of Stabilization?mentioning

confidence: 97%

Section: Accumulation At the Polymer Surface: What Are The Sources Of Stabilization?mentioning

confidence: 99%

The Hofmeister series: Specific ion effects in aqueous polymer solutions

Moghaddam

Thormann

2019

Journal of Colloid and Interface Science

132

116

View full text Add to dashboard Cite

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“…By referencing the spline back to the interfacial volume in this manner, penalty terms (e.g. a Lagrange multiplier) are not required to enforce interfacial volume or monotonicity constraints (Murdoch et al, 2017(Murdoch et al, , 2016Geoghegan et al, 2006;Jia et al, 2012). The low number of knots removes the need to penalize oscillating profiles, as they will not be produced by the model even when monotonicity is not enforced.…”

Section: Research Papersmentioning

confidence: 99%

Quantifying the robustness of the neutron reflectometry technique for structural characterization of polymer brushes

et al. 2021

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Neutron reflectometry is the foremost technique for in situ determination of the volume fraction profiles of polymer brushes at planar interfaces. However, the subtle features in the reflectometry data produced by these diffuse interfaces challenge data interpretation. Historically, data analyses have used least-squares approaches that do not adequately quantify the uncertainty of the modeled profile and ignore the possibility of other structures that also match the collected data (multimodality). Here, a Bayesian statistical approach is used that permits the structural uncertainty and multimodality to be quantified for polymer brush systems. A free-form model is used to describe the volume fraction profile, minimizing assumptions regarding brush structure, while only allowing physically reasonable profiles to be produced. The model allows the total volume of polymer and the profile monotonicity to be constrained. The rigor of the approach is demonstrated via a round-trip analysis of a simulated system, before it is applied to real data examining the well characterized collapse of a thermoresponsive brush. It is shown that, while failure to constrain the interfacial volume and consider multimodality may result in erroneous structures being derived, carefully constraining the model allows for robust determination of polymer brush compositional profiles. This work highlights that an appropriate combination of flexibility and constraint must be used with polymer brush systems to ensure the veracity of the analysis. The code used in this analysis is provided, enabling the reproduction of the results and the application of the method to similar problems.

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“…This characteristic makes such gradient copolymers a great potential in biomimetic applications. [21][22][23][24][25][26][27][28][29] Various studies are done on the effect of additives on the solubility behavior of thermoresponsive polymers [30][31][32][33][34][35][36][37][38][39] including POEOMAs, [40][41][42][43][44] but so far there is no comprehensive study to compare the effect of different additives on the phase transition of thermoresponsive copolymers with different structure.…”

Section: Introductionmentioning

confidence: 99%

Solubility behaviour of random and gradient copolymers of di- and oligo(ethylene oxide) methacrylate in water: effect of various additives

2020

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Poly[oligo(ethylene oxide)] based gradient and random copolymers with different compositions are synthesized via Cu-based atom transfer radical polymerization. The solubility behavior of these copolymers in pure water and in the presence of different salts, surfactants and ethanol is investigated. According to dynamic light scattering results, the lower critical solution temperature (LCST) depends on the structure of the copolymer and changes slightly in the presence of additives. Good cosolvents like ethanol can increase the LCST through dissolving the collapsed copolymer chains to some extent. The same effect is observed for surfactants that make the copolymer solution more stable by preventing aggregation.Above a certain concentration of surfactant, depending on the copolymer structure, the solution is stable at all temperatures (no LCST). The effect of salts on the solubility of the copolymers follows the Hofmeister series and it is related linearly to the salt concentration. Based on their affinity to the copolymer, the salts can increase or decrease the LCST. There is a considerable difference in phase transition changes for gradient or random copolymers after salt addition. While both copolymers show a two-step phase transition in the presence of different salts, the changes in the hydrodynamic radius and normalized scattering intensity are rather broad for random compared to gradient copolymers. Contrary to what was expected, varying the cations has no distinguishable effect on the LCST for both copolymers. All chlorides decrease the LCST. This decrease is almost the same for gradient copolymers and fluctuates for random copolymers.

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Enhanced specific ion effects in ethylene glycol-based thermoresponsive polymer brushes

Cited by 34 publications

References 60 publications

The Hofmeister series: Specific ion effects in aqueous polymer solutions

The Hofmeister series: Specific ion effects in aqueous polymer solutions

Quantifying the robustness of the neutron reflectometry technique for structural characterization of polymer brushes

Solubility behaviour of random and gradient copolymers of di- and oligo(ethylene oxide) methacrylate in water: effect of various additives

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