Masking specific effects of ionic liquid constituents at the solid–liquid interface by surface functionalization

Katana, Bojana; Takács, Dóra; Bobbink, Félix D.; Dyson, Paul J.; Alsharif, Nizar B.; Tomšič, Matija; Szilágyi, István

doi:10.1039/d0cp02805c

Cited by 12 publications

(15 citation statements)

References 45 publications

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“…This conclusion is further confirmed by the very similar zeta potentials measured in the same systems. Such a masking phenomenon was already reported earlier in the case of polymeric latex particles functionalized with IP-2 …”

Section: Resultssupporting

confidence: 79%

“…Such a U-shaped curve is typical for systems containing oppositely charged polyelectrolytes and particles including HNTs. 15,17,22,66 Referring to the data sets shown in Figure 2, stable samples were observed at 1 and 200 mg/g, moderate stability was observed at 25 mg/g, while rapid particle aggregation occurred at 10 mg/g. These findings are in qualitative agreement with the prediction of DLVO theory, since attractive forces destabilize the samples at charge neutralization (10 mg/g) while sufficiently charged particles (1 and 200 mg/g) are stable due to repulsion between the electrical double layers.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

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Aggregation of Halloysite Nanotubes in the Presence of Multivalent Ions and Ionic Liquids

et al. 2021

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Colloidal stability was investigated in two types of particle systems, namely, with bare (h-HNT) and polyimidazoliumfunctionalized (h-HNT−IP-2) alkali-treated halloysite nanotubes in solutions of metal salts and ionic liquids (ILs). The valence of the metal ions and the number of carbon atoms in the hydrocarbon chain of the IL cations (1-methylimidazolium (MIM + ), 1-ethyl-3methylimidazolium (EMIM + ), 1-butyl-3-methylimidazolium (BMIM + ), and 1-hexyl-3-methylimidazolium (HMIM + )) were altered in the measurements. For the bare h-HNT with a negative surface charge, multivalent counterions destabilized the dispersions at low values of critical coagulation concentration (CCC) in line with the Schulze−Hardy rule. In the presence of ILs, significant adsorption of HMIM + took place on the h-HNT surface, leading to charge neutralization and overcharging at appropriate concentrations. A weaker affinity was observed for MIM + , EMIM + , and BMIM + , while they adsorbed on the particles to different extents. The order HMIM + < BMIM + < EMIM + < MIM + was obtained for the CCCs of h-HNT, indicating that HMIM + was the most effective in the destabilization of the colloids. For h-HNT−IP-2 with a positive surface charge, no specific interaction was observed between the salt and the IL constituent cations and the particles, i.e., the determined charge and aggregation parameters were the same within experimental error, irrespective of the type of co-ions. These results clearly indicate the relevance of ion adsorption in the colloidal stability of the nanotubes and thus provide useful information for further design of processable h-HNT dispersions.

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Section: Resultssupporting

confidence: 79%

Section: ■ Experimental Methodsmentioning

confidence: 99%

Aggregation of Halloysite Nanotubes in the Presence of Multivalent Ions and Ionic Liquids

et al. 2021

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“…However, at IP-2 doses near to the IEP, the rate values increase indicating a rapid particle aggregation and hence, unstable samples. Such a charging and aggregation behaviors resemble the one observed earlier in oppositely charged polyelectrolyte-particle systems [31,36,44,45] and are in qualitative agreement with the DLVO theory, which predicts the stable dispersions in case, when the surface charge is high and the corresponding repulsive double layer forces prevail the attractive van der Waals interactions [46].…”

Section: Ip-2 Functionalization Of Slsupporting

confidence: 87%

“…Therefore, this paper provides an improved understanding of how the above-mentioned factors govern the interfacial composition, as the presented findings offer tools for tuning and optimizing the stability of IL-particle dispersions for specific applications. Note that surface charges and aggregation rates were also explored by our group in other particle-IL systems, but those studies concentrated on particles dispersed in diluted aqueous IL solutions [30,31,36,37]. The present work focuses on a much wider range of IL concentration (up to pure EAN) and on the effect of both water and salt content on the colloidal stability of the dispersions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Water and Salt on the Colloidal Stability of Latex Particles in Ionic Liquid Solutions

Takács

Tomšič

Szilágyi

2021

Colloids and Interfaces

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The colloidal stability of sulfate (SL) and polyimidazolium-modified sulfate (SL-IP-2) latex particles was studied in an ionic liquid (IL) of ethylammonium nitrate (EAN) and its water mixtures. Aggregation rates were found to vary systematically as a function of the IL-to-water ratio. Repulsive electrostatic interactions between particles dominated at low IL concentrations, while they were significantly screened at intermediate IL concentrations, leading to destabilization of the dispersions. When the IL concentration was further increased, the aggregation of latex particles slowed down due to the increased viscosity and finally, a striking stabilization was observed in the IL-rich regime close to the pure IL solvent. The latter stabilization is due to the formation of IL layers at the interface between particles and IL, which induce repulsive oscillatory forces. The presence of the added salt in the system affected differently the structure of the interfaces around SL and SL-IP-2 particles. The sign of the charge and the composition of the particle surfaces were found to be the most important parameters affecting the colloidal stability. The nature of the counterions also plays an important role in the interfacial properties due to their influence on the structure of the IL surface layers. No evidence was observed for the presence of long-range electrostatic interactions between the particles in pure ILs. The results indicate that the presence of even low concentrations of water and salt in the system (as undesirable impurities) can strongly alter the interfacial structure and thus, the aggregation mechanism in particle IL dispersions.

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“…Previous studies [30][31][32][33][34] on other particle-IL systems pointed out that ion specific effects, similar to inorganic electrolytes, [35][36][37] are important in the presence of IL constituents since they govern the adsorption of ions from solutions. Moreover, IL cations and anions can be arranged in sequences based on their adsorption affinity to a given surface.…”

Section: Introductionmentioning

confidence: 99%

Influence of adsorption of ionic liquid constituents on the stability of layered double hydroxide colloids

et al. 2021

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Masking specific effects of ionic liquid constituents at the solid–liquid interface by surface functionalization

Abstract: Ion specific effects of ionic liquid (IL) constituents on charging and aggregation phenomena of two types of particles (positively charged amidine (AL) and polyimidazolium-functionalized sulfate (SL-IP-2) latexes) were investigated in...

Cited by 12 publications

References 45 publications

Aggregation of Halloysite Nanotubes in the Presence of Multivalent Ions and Ionic Liquids

Aggregation of Halloysite Nanotubes in the Presence of Multivalent Ions and Ionic Liquids

Effect of Water and Salt on the Colloidal Stability of Latex Particles in Ionic Liquid Solutions

Influence of adsorption of ionic liquid constituents on the stability of layered double hydroxide colloids

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