Molecular Simulations for Understanding the Stabilization of Fullerenes in Water

Noneman, Kendra; Muhich, Christopher L.; Ausman, Kevin D.; Henry, Mike; Jankowski, Eric

doi:10.22369/issn.2153-4136/12/1/6

Cited by 3 publications

(3 citation statements)

References 45 publications

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“…Solutions of fullerenes and their derivatives remain the focus of attention for researchers in various fields, , including photovoltaics, , electrochemistry, and biomedicine. , Therefore, new publications continue to report on the properties of fullerenes in non-aqueous ,− and aqueous ,,,, solutions. In polar solutions, fullerenes readily form colloids.…”

Section: Introductionmentioning

confidence: 99%

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

et al. 2022

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It is known that fullerenes are poorly soluble in polar solvents, but readily form colloidal solutions in such media. These solutions are typically solvophobic (hydrophobic when prepared in water), that is, thermodynamically unstable colloidal systems with negatively charged particles. To understand the stability factors of a colloidal system, the thresholds for coagulation of a sol or suspension by electrolytes are of key importance. While hydrosols and aqueous suspensions coagulate at concentrations of 1:1 inorganic electrolytes about 0.1− 0.2 M, in acetonitrile and methanol, the corresponding critical concentrations of coagulation are ca. 3 orders of magnitude lower. Given the wide variety of properties of organic solvents, it seemed important to complete the picture to study solvents with more basic properties. This is all the more reasonable since electrophilic fullerenes are in fact Lewis acids. Our choice was dimethyl sulfoxide, DMSO, and related solvent systems. The colloidal solutions of fullerenes C 60 and C 70 in DMSO and N,N-dimethyl formamide, DMF, are unexpectedly easy to prepare by mechanical methods, and addition of water leads to formation of relatively stable organo-hydrosols. UV−visible spectra and dynamic light scattering were used to characterize the solutions of C 60 and C 70 in DMSO, benzene−DMSO, acetonitrile−DMSO, and benzene−acetonitrile−DMSO systems, as well as in DMF. Our present study demonstrated that, in contrast to organosols in methanol and acetonitrile, colloids of C 70 and C 60 fullerenes in DMSO and DMF are surprisingly as stable with respect to electrolytes as the corresponding hydrosols are. Such high stability is caused by the non-DLVO interactions, or, in terms proposed by Churaev and Derjaguin, by the so-called structural effect. These results shed light on the nature of the solvation of colloidal fullerene particles in solvents of various chemical natures.

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Section: Introductionmentioning

confidence: 99%

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

et al. 2022

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“…The main idea of this and of previous works of this group [183,187,209] consists of stabilization of C 60 colloids in water by admixtures of C 60 O. The latter to some extent plays the role of a diphilic compound, a kind of stabilizing surfactant [221]. This is quite plausible, but the fullerene oxide itself cannot cause the surface charge, and it is the charge screening by electrolytes that leads to coagulation.…”

Section: Hydrosols Of Fullerenes: Key Propertiesmentioning

confidence: 99%

“…In any case, the negative charge is a main factor of the aggregative stability of colloids including fullerene sols and suspensions. Noneman et al [221] performed a detailed molecular dynamics modeling of mixtures of C 60 with C 60 O in water. The main idea of this and of previous works of this group [183,187,209] consists of stabilization of C 60 colloids in water by admixtures of C 60 O.…”

Section: Hydrosols Of Fullerenes: Key Propertiesmentioning

confidence: 99%

Colloid Chemistry of Fullerene Solutions: Aggregation and Coagulation

Mchedlov-Petrossyan,

Marfunin,

Kriklya

2023

Liquids

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This review article is devoted to the colloidal properties of fullerene solutions. According to generally accepted understandings, all solvents in relations to fullerenes are divided into “good”, “poor”, and “reactive”. We have consistently considered the state of fullerenes in these systems. In “good”, predominantly non-polar aromatic solvents and CS2, non-equilibrium dissolution methods lead to the formation of colloidal aggregates, whereas the utilization of equilibrium methods results in the formation of molecular solutions. The latter, however, have some unusual properties; new results considered in this review confirm previously expressed ideas about colloidal properties of these solutions. In “poor” (polar) solvents, lyophobic colloidal systems appear. Both “bottom-up” and “top-down” methods of preparation are well documented in the literature. However, N-methylpyrrolidine-2-one, DMSO, and DMF dissolve fullerenes quite easily and with less energy consumption. These solvents can be considered a subset of “poor” solvents that have some features of being “reactive” at the expense of basic properties. New data confirm that hydrosols of fullerenes are typical hydrophobic colloids that obey the Schulze–Hardy rule and other regularities in the presence of electrolytes. Organosols in acetonitrile and methanol are much less stable with respect to the effects of electrolytes. This allows us to assume a non-DLVO stabilizing factor in the hydrosols. Accordingly, a new estimate of the Hamaker constant of fullerene–fullerene interaction is proposed. In DMSO and DMF, the coagulation of fullerene sols is hindered due to strong solvation with these basic solvents.

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Hydrosol of C70 Fullerene: Synthesis and Stability in Electrolytic Solutions

et al. 2021

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This article is devoted to the synthesis and characterization of the hydrosol of C70 of the son/nC70 type and to its coagulation by sodium chloride and cetyltrimethylammonium bromide (CTAB). At C70 concentration of 3.3×10–6 M, the electrokinetic potential is ζ= –40 ± 4 mV, the particle size expressed as Zeta-average is 97±3 nm; at higher C70 concentrations, 1.7×10–5 and 6.9×10–5 M, the size stays the same: 99 – 100 nm. The critical concentration of coagulation (CCC) values, were determined using the diameter increasing rate (DIR) on NaCl concentration. The CCCs are concentration-dependent: 250, 145, and 130 mM at C70 concentrations 3.3×10–6, 1.7×10–5, and 6.9×10–5 M, respectively. The CCC for the CTAB surfactant is much lower, about 5×10–3 mM. At 0.02 mM CTAB, however, the overcharging up to ζ = + 40 mV and stabilization of the colloidal particles take place. Interpretation of the hydrosol coagulation by NaCl using the Derjaguin–Landau–Verwey–Overbeek theory makes it possible to determine the Hamaker constant of the C70–C70 interaction in vacuum, if only electrostatic repulsion and molecular attraction are taking into account: AFF ≈ 7×10–20 J. On the other hand, if we use the value AFF = (16.0–16.6)×10–20 J, obtained earlier in the study of organosols, then the data for hydrosols can be explained only by the introduction of an additional type of interactions. Following the terms of Churaev and Derjaguin, one should take into account the structural contribution to the interaction energy, which stabilizes the hydrosol.

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Molecular Simulations for Understanding the Stabilization of Fullerenes in Water

Cited by 3 publications

References 45 publications

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

Unexpected Colloidal Stability of Fullerenes in Dimethyl Sulfoxide and Related Systems

Colloid Chemistry of Fullerene Solutions: Aggregation and Coagulation

Hydrosol of C70 Fullerene: Synthesis and Stability in Electrolytic Solutions

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