HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS
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 expresse...
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| Date: | 2021 |
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V.I.Vernadsky Institute of General and Inorganic Chemistry
2021
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Ukrainian Chemistry Journal| _version_ | 1871465756667936768 |
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| author | Mchedlov-Petrossyan, Nikolay Marfunin, Mykyta Klochkov , Volodymyr Radionov, Petro |
| author_facet | Mchedlov-Petrossyan, Nikolay Marfunin, Mykyta Klochkov , Volodymyr Radionov, Petro |
| author_institution_txt_mv | [
{
"author": "Nikolay Mchedlov-Petrossyan",
"institution": "V. N. Karazin Kharkiv National University, Svobody sq., 4, Kharkiv, 61022, Ukraine"
},
{
"author": "Mykyta Marfunin",
"institution": "PhD student, Department of Physical Chemistry, V.N. Karazin Kharkiv National University"
},
{
"author": "Volodymyr Klochkov ",
"institution": "Сandidate of science (PhD), senior researcher, Institute for Scintillation Materials NAS of Ukraine"
},
{
"author": "Petro Radionov",
"institution": "BSc student, chemical faculty, V.N. Karazin Kharkiv National University"
}
] |
| author_sort | Mchedlov-Petrossyan, Nikolay |
| baseUrl_str | https://ucj.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T08:23:47Z |
| description | 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. |
| doi_str_mv | 10.33609/2708-129X.87.10.2021.63-73 |
| first_indexed | 2025-09-24T17:43:41Z |
| format | Article |
| fulltext |
63
УДК 544.77.05+546.26+544.353.3 doi: 10.33609/2708-129X.87.10.2021.63-73
HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY
IN ELECTROLYTIC SOLUTIONS
M. O. Marfunin,a V. K. Klochkov,b P. M. Radionov,a N. O. Mchedlov-Petrossyana
a V. N. Karazin Kharkiv National University, 4 Svoboda sq., Kharkiv, 61022, Ukraine
b Institute for Scintillation Materials NAS of Ukraine, 61001 Kharkіv, Ukraine
e-mail: mchedlov@karazin.ua
This article is devoted to the synthesis and characterization of the C70 hydrosol of the
son/nC70 type and to its coagulation by sodium chloride and cetyltrimethylammoni-
um 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 concen-
trations, 1.7×10–5 and 6.9×10–5 M, the size stays the same: 99 – 100 nm. The critical concentra-
tion 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.
Keywords: fullerene C70 hydrosol, electrokinetic potential, sodium chloride, cetyltrime
thylammonium bromide, critical concentration of coagulation, Derjaguin – Landau – Ver-
wey – Overbeek theory, Hamaker diagram, fullerene–fullerene Hamaker constant, structural
contribution to the inter-particle interaction.
HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS
64 ISSN 2708-129X. Укр. хім. журн., 2021
PHYSICAL CHEMISTRY
INTRODUCTION. The chemistry of fulle
rene solutions, including colloidal ones, is
still one of the most interesting areas of nano
science. Recent reviews give some idea of the
current state of affairs in this area [1–3]. An
important issue is the nature of aqueous sus-
pensions and hydrosols of fullerenes [2]; the
results of new detailed studies of these systems
were published this year [4–6]. The last work
[6] develops a previously published technique
of preparation of the C60 hydrosol from the
fullerene anion radical [7]. Another group of
authors [8] published a molecular dynamics
simulation study to understand the stabiliza-
tion of fullerenes in water; the discussion was
based on the idea of important role of the oxi
dized species C60O, which was previously put
forward by the Ausman’s group [9].
During a study of C70 organosols in acetonit
rile-based solvents and some other systems
[10], as well as analogous dispersions of C60
[11, 12], we estimated the Hamaker constant,
AFF, of fullerene-fullerene interactions basing
on the Derjaguin–Landau–Verwey–Overbeek
(DLVO) theory. There are, however, two expla-
nations of the data [10]. First one is based on
averaging-out all the estimates obtained with
different electrolytes. The average AFF value
is close to that estimated in aqueous systems
[13–15], but the scatter is substantial. Alterna-
tively, utilization of only several selected sys-
tems results in a substantially higher AFF [10].
If the last value is accepted, the presence of a
strong stabilizing factor in hydrosols should be
presumed.
This paper is aimed to characterize the
stability of the C70 hydrosol of the so-called
son/nC70 type prepared by a somewhat modi
fied procedure. Earlier Aich et al. [16, 17]
studied in detail this hydrosol as well as those
formed by C60, C76, and C84. Values of the cri
tical concentrations of coagulation of fullerene
hydrosols and suspensions by electrolytes pub-
lished in the literature were gathered in a re-
view paper [2].
EXPERIMENT AND DISCUSSION OF THE
RESULTS. Preparation of the C70 hydrosol. The
first stage consisted in preparing a solution of
fullerene in benzene. It is importantly to note
that the water content in benzene should not
exceed 0.01%. A weight amount of C70 (Neo-
TechProduct, >99%) was placed into benzene
without intensive mixing; the final concentra-
tion was 5×10–4 M. The solution was stored for
two weeks, stirring slowly every 3–5 days, and
then filtered through a 0.22 μm membrane fil-
ter. The second stage was aimed to transfer the
fullerene from benzene to water. In a 500 ml
beaker, 400 ml of deionized water (conduc-
tivity ≤ 1.0 μS) was added and 30 ml of a C70
benzene solution (2.5×10–4 M) was added. The
titanium tip of an ultrasonic disperser (22 kHz,
400–600 W) is immersed in the solution. Soni
cation was performed at reduced pressure
of 100 mm. Hg. First, a white emulsion was
formed. Then, the solution becomes trans-
parent with brown tint. The solution thus ob-
tained was centrifuged for 15–20 min at 7000–
8000 rpm in order to remove the titanium par-
ticles and the coarse fraction of C70 particles.
The supernatant part of the solution is placed
in a round-bottomed flask of a rotary evapo-
rator and evaporated at a bath temperature of
65 ºС to 12 – 15 ml. Then the solution is filtered
through membrane filters with pore diameters
of 0.45 and 0.22μm. The result is a clear dark
brown solution containing (6–8)×10–4 M C70.
Determination of the fullerene concentra-
tion and molar absorptivity in water. 2 ml of
C70 aqueous solution are placed in a 10 ml eva
M. O. Marfunin, V. K. Klochkov, P. M Radionov, N. O. Mchedlov-Petrossyan
65https://ucj.org.ua
UCJ № 10 / Vol. 87
porating flask and evaporated to dryness on
a rotary evaporator. Then, 2 ml of a mixture
of water/acetone in a ratio of 1: 1 are poured
into the flask and evaporated to dryness. Then
2 ml of acetone is poured into the flask twice
and each time is evaporated to dryness. After
drying and removing traces of acetone, 2 ml
of benzene are placed in the flask and left to
dissolve completely. The concentration of the
fullerene in the hydrosol, 4.30×10–4 M, was es-
timated using the molar absorptivity of C70 in
benzene, 44.7×103 M–1cm–1, at 382.1 nm. {The
molar absorptivity in benzene was estimated
by 100-fold dilution by highly purified tolu-
ene and using the molar absorptivity of C70 in
toluene used previously [10]}. Then, the molar
absorptivity of C70 in the hydrosol at 385.7 nm
was estimated as 48.0×103 M–1cm–1. The ab-
sorption spectra are presented in Figure 1.
Figure 1 – UV/visible absorption spectra of C70
in different media.
This spectrum of the hydrosol is very simi-
lar to those reported by Aich et al. [16, 17] and
Mikheev et al. [18].
Other chemicals. To determine the hydro-
sols CCC, the solutions of NaCl (analytical
grade) and cetriltrimethylammonium bro-
mide (CTAB, 99 %, Sigma-Aldrich) were used.
These solutions were prepared by dissolving of
required salt amount in distillate water.
Preparation of the working solutions. The
required amount of electrolyte solution was
added to the flask, then distillate water. After
mixing, an aliquot of the C70 stock solution was
added to the flask and the solution was stirred
again.
Apparatus. UV/visible spectra were run
with a Hitachi U-2000 spectrophotometer
against solvent blanks. Particle size distribution
was obtained using dynamic light scattering
via Zetasizer Nano ZS Malvern Instruments,
scattering angle 173о; each measurement was
made by 12 runs and reproduced at least three
times. The values of the ζ-potentials were de-
termined using the Zetasizer Nano ZS Mal-
vern Instruments, scattering angle 12.8o; each
measurement was performed by 3–5 runs. The
spectral and DLS measurements were made at
25.0±0.5 oC.
Characterization of the hydrosols. Particle
size distribution at different fullerene concen-
trations is presented in Figure 2.
Figure 2 – Particle size distribution of the
son/nC70 hydrosol at various dilutions of the ini-
tial sol.
HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS
66 ISSN 2708-129X. Укр. хім. журн., 2021
PHYSICAL CHEMISTRY
Main experiments were processed with the
concentration of 3.29×10–6 M C70. The par-
ticles are negatively charged, ς = –40 ± 4 mV.
The Z-average value is d = 97 ± 3 nm (by number
51 nm; by volume 60; by intensity 110; PDI =
0.18). For C70 concentration of 1.71×10–5 M,
Z-average is 99 nm; the size by number, vo
lume, and intensity is 51; 63; and 114 nm,
and PDI = 0.18. For 6.91×10–5 M C70, the cor-
responding values are 100 nm; 51; 59; and
120 nm, PDI = 0.22. All the values of the
zeta-potential presented here are calculated
using the Ohshima equation [19, 20]; in salt-
free water, this corresponds to the Onsager–
Hückel equation. Note, that other authors [15,
16, 18, 21] use the Smoluchowsky equation.
Aich et al. report the hydrodynamic dia
meter of 92 ± 14 nm and ς= –39 ± 4 mV [15],
Mikheev et al. [18] report d = 175±5 nm
(PDI = 0.11±0.02), ς= –34.4 ± 0.7 mV (measu
rements at 6.2×10–5 M C70).
Coagulation by sodium chloride. The critical
coagulation concentration was determined us-
ing the dependence of the diameter increasing
rate (DIR) on NaCl concentration (Figure 3),
which is in fact a sort of the Fuchs approach
[10–15, 17].
Figure 3 – Determination of the critical coagulation concentration of the C70 hydrosol by NaCl: the
results of two independent experiments; asterisks indicate the ς values.
The CCC value at 3.3×10–6 M C70 is 250 mM
NaCl. Increasing in the fullerene concentra-
tion up to 1.71×10–5 M decreases the CCC va
lue down to 145 mM. This is in line with the re-
sults obtained with C60 hydrosols [2]. Further
rise of C70 concentration to 6.91×10–5 M also
decreases the CCC to 130 mM. However, the
system is unstable under such conditions, and
the coagulation occurs in spurts. Note, that at
1×10–4 M of C60 hydrosol CCC = 85 mM NaCl
(determined by visual titration) [22]. Aich
et al. [17] reported a CCC value of 150 mM
at 7.9×10–7 M C70 (the fullerene concentra-
tion was calculated using the information on
the experimental details kindly sent to us by
Dr. Aich).
Interaction of the C70 hydrosol particles with
CTAB. Small concentrations of CTAB cause
charge neutralization of the particles and coa
gulation of the hydrosol; the size jump ap-
proximately corresponds to the isoionic state
(Figure 4). The CCC value is about 0.005 mM
CTAB. In contrast, further increase in CTAB
concentration results in overcharging and
M. O. Marfunin, V. K. Klochkov, P. M Radionov, N. O. Mchedlov-Petrossyan
67https://ucj.org.ua
UCJ № 10 / Vol. 87
thus stabilization of the sol. This phenome-
non is typical for colloidal systems, e.g., for the
SiO2/CTAB [23]. Whereas the coagulation
within the range of micromolar CTAB concen-
trations is obviously caused by adsorption and
hence charges neutralization of colloidal parti-
cles, the stabilization via particles overcharging
is probably a result of surfactant bilayer forma-
tion [22, 24].
Interpretation of the CCC(NaCl) value.
Despite some differences of the CCCs deter-
mined at various C70 concentrations and by
different authors, these values as well as those
for C60 hydrosol [2, 13-15, 17, 18, 21, 22],
are two-three orders of magnitude higher as
compared with the values in organic solvents
[10–12]. In both cases, attempts were made
to estimate the fullerene–fullerene Hamaker
constant, AFF, which characterizes the C70–C70
interaction in vacuum, selecting in one way
or another a value consistent with a given
coagulation threshold. For example, an equa-
tion derived by Dukhin et al. [25] can be used,
Eq. 1.
Figure 4 – Size and zeta-potential dependence of the C70 colloid in CTAB solutions; asterisks indicate
the ς values.
7
stabilization via particles overcharging is probably a result of surfactant bilayer formation [22,
24].
Figure 4 – Size and zeta-potential dependence of the C70 colloid in CTAB solutions; asterisks
indicate the values.
Interpretation of the CCC(NaCl) value. Despite some differences of the CCCs determined at
various C70 concentrations and by different authors, these values as well as those for C60
hydrosol [2, 13-15, 17, 18, 21, 22], are two-three orders of magnitude higher as compared with
the values in organic solvents [10–12]. In both cases, attempts were made to estimate the
fullerene–fullerene Hamaker constant, FFA , which characterizes the C70–C70 interaction in
vacuum, selecting in one way or another a value consistent with a given coagulation threshold.
For example, an equation derived by Dukhin et al. [25] can be used, Eq. 1.
U = + = (1)
Here, h is the distance between the centers of the particles, = 2 + , d is the
electrical surface potential of the colloidal particles, 0 = 8.854 10–12 F m–1, is the reciprocal
Debye length, R, T, F have their usual meanings. The measured values of can be used for low
and medium charged interfaces instead of , in accord to the accepted viewpoint. The
value characterizes the fullerene – solvent – fullerene interaction in solution and is connected
elU attrU
2
2 d
0
exp( )64 tgh
4r
FRT r h
F RT s
2
FSF
2 2 2
2 2 4ln
6 4
A s
s s s
s /h r
d *
FSFA
Here, h is the distance between the centers
of the particles, s = 2 + /h r , dΨ is the electri-
cal surface potential of the colloidal particles,
0ε = 8.854× 10–12 F m–1, κ is the reciprocal
Debye length, R, T, F have their usual mean-
ings. The measured values of ς can be used for
low and medium charged interfaces instead of
dΨ , in accord to the accepted viewpoint. The
*
FSFA value characterizes the fullerene – sol-
vent – fullerene interaction in solution and is
connected with the AFF and ASS values, which
characterize the fullerene–fullerene and sol-
vent–solvent interactions in vacuum, respec-
tively, through Eq. 2.
* 1/2 1/2 2
FSF FF SS( )A A A= − . (2)
Different dependences of U on h can be
constructed using various *
FSFA values, and
those which meet the coagulation conditions
should be selected. Accordingly, the FFA can
HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS
68 ISSN 2708-129X. Укр. хім. журн., 2021
PHYSICAL CHEMISTRY
be estimated using Eq. 2. In our recent work,
in this way we estimated the A*
FSF and AFF va-
lues for C70 in acetonitrile and methanol (with
10 vol. % toluene) [10]. Using the data for a
set of electrolytes, we obtained the AFF values
within a wide range of (5.8 – 16.6)×10–20 J
[10]; similar AFF were estimated for C60 in
acetoni-trile and methanol [11, 12].
At the same time, Elimelech and his co-
workers obtained the value FFA = 7.5×10–20 J
for C60 hydrosols prepared by different proce-
dures [13, 15]. Aich et al. [17] used this value
for successful explanation of the coagulation of
aqueous suspensions of C60, C70, C76, and C84.
Therefore, the data obtained with organosols
can be considered as an approximate estimate,
with the value 7.5 × 10–20 J falling within this
range.
However, an alternative explanation can be
proposed. A careful consideration of the data
for organosols demonstrates an expressed
tendency to overcharging of the negatively
charged colloidal particles of the fullerenes
by the metal cations. This most likely leads
to hetero- and mutual coagulation, and the
simple interpretation of the CCCs using Eq. 1
becomes impossible. Therefore, we select-
ed the data for two electrolytes as coagula-
tors in organic solvents. They are as follows:
tetra-n-butylammonim perchlorate, chosen
because of no signs of overcharging, and cal-
cium perchlorate, which exhibits a second
CCC value for completely overcharged C70
aggregates [10]. This allows estimating the
FFA value (16.0 – 16.6) ×10–20 J [10], which
is substantially higher as compared with the
“aqueous” value, FFA = 7.5×10–20 J. This, in
turn, allows suspecting the presence of an
additional stabilizing factor in the case of the
hydrosols [10].
In Figure 5, series of Hamaker diagrams are
presented for ionic strength of 250 mM and ς =
–17 mV, i.e., under conditions of rapid coagu-
lation by NaCl (see above), and different *
FSFA
values; SSA for water is 3.86×10-20 J.
Figure 5 – Hamaker diagrams for the C70 hydro-
sol for 250 mM NaCl.
In Figure 6, the maxU values in kBT units are
plotted against the *
FSFA values.
Figure 6 – Potential barrier height as a func-
tion of the Hamaker constant.
If the values of the potential barrier maxU =
(0 – 1) kBT are accepted as the margin of the
stability, then FFA = (7.0 to 6.2)×10–20 J (Ta-
ble 1). Average value is 6.6×10–20 J; for maxU = 0,
FFA = 7.0×10–20 J.
M. O. Marfunin, V. K. Klochkov, P. M Radionov, N. O. Mchedlov-Petrossyan
69https://ucj.org.ua
UCJ № 10 / Vol. 87
Table 1
Calculated values of the Hamaker con-
stant.
maxU , kBT *
FSFA , 10-20 J AFF, 10-20 J
0.00 0.47 7.02
1.00 0.27 6.17
2.00 0.17 5.65
Mean 0.30 6.3
These estimates are in line with the above
mentioned publications [13, 15]. On the
other hand, if we use the “refined” data ob-
tained from the examination of organosols,
AFF = (16.0 to 16.6)×10–20 J, then the picture
changes radically. In Figure 7, the Hamaker
diagrams are constructed with these values. For
ionic strength of 100 mM, ς = –22 mV and the
DIR value is low but not zero (heavy curve).
Here, as well as for higher NaCl concentra-
tions, the system would have to be completely
unstable, while experimentally the slow coagu-
lation is observed (Figure 3). At 30 mM NaCl,
where the system is quite stable (ς = –30 mV,
DIR approaches zero), the barrier height is
about 0.5 kBT (light curves, built for several AFF
values from 16.0×10–20 J to 16.6×10–20 J). Thus,
here the rapid coagulation can be expected,
which is, however, not the case (Figure 3).
Figure 7 – Hypothetical Hamaker diagrams based on molecular attraction, AFF = (16.0 to 16.6)×10–20 J,
and electrostatic repulsion.
Therefore, the experimental CCC is ca. one
order of magnitude higher than the predicted
threshold calculated with the AFF values esti-
mated in organic solvents. As it was mentioned
above, an interaction that stabilizes the hydro-
sol should be expected. According to Derjagu-
in and Churaev, a structural (hydration) con-
tribution to the disjoining pressure must be
taken into account [26]. In other words, the U
value in Eq. 1 may contain an additional quan-
tity, sU , Eq. (3).
exp( / )sU Kl h l= − . (3)
Here K and l are constants; for hydrophilic
and hydrophobic surfaces, K > 0 (structural
repulsion) and K < 0 (structural attraction),
respectively. Without knowing the two con-
stants, K and l, it is difficult to draw precise
HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS
70 ISSN 2708-129X. Укр. хім. журн., 2021
PHYSICAL CHEMISTRY
quantitative conclusions. In fact, the addi
tional contribution, sU , is opposed to the
second item of the rhs of Eq. 1, but the type
of the function is exponential. Approximate
estimation for AFF = 7.0×10–20 J is as follows: at
30 mM NaCl and ς = –30 mV, the maxU value
is 26 kBT. This value is much higher than that
given in Figure 7. If the U value is compared at
the distance, which corresponds to the barrier
maximum in Figure 7, the difference is around
13 kBT. In any case, the model proposed in the
present paper looks out as self-consisted. This
also is in line with numerous reports devoted
to specific fullerene–water interactions [2, 10,
27–31].
CONCLUSIONS. The C70 hydrosol prepared
by solvent-exchange method (a system of the
son/nC70 type) is characterized by a electro
kinetic potential of –40 ± 4 mV and particle
size 97±3 nm at fullerene concentration of
3.3×10–6 M. The critical concentrations of coa
gulation (CCC) values are decreasing from
250 to 130 mM NaCl along with the rise of
the hydrosol concentration from 3.3×10–6 to
6.9×10–5 M. The CCC for the CTAB surfactant
is about 5×10–3 mM, i.e., fifty thousand times
lower. Higher CTAB concentrations lead to
overcharging of the colloidal particles up to
ζ = + 40 mV and stabilization of the hydrosol.
Using the DLVO theory to explain the coa
gulation of the hydrosol by NaCl allows deter-
mining 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 the value AFF = (16.0–16.6)×10–20 J,
obtained earlier during the study of organo-
sols, is used, then the data for hydrosols can
be explained only by taking into account an
additional type of interactions. Following the
terms of Churaev and Derjaguin, one should
take into account the structural contribution
to the interaction energy, sU , which stabilizes
the hydrosol.
ACKNOWLEDGMENTS
This study was partly supported by
the Ministry of Education and Science
of Ukraine, grant 0119U002532. The
authors express their gratitude to Dr. Nirupam
Aich, University at Buffalo, USA, for informing
about some details of his experiments reported
in ref. [16, 17].
ГІДРОЗОЛЬ ФУЛЕРЕНУ С70: СИНТЕЗ ТА
СТАБІЛЬНІСТЬ В ЕЛЕКТРОЛІТИЧНИХ
РОЗЧИНАХ
M. O. Марфунін,1 В. К. Клочков,2
П. M. Радіонов,1 М. О. Мчедлов-Петросян1
1Харківський національний університет
імені В. Н. Каразіна, пл. Свободи, 4, Харків
61022, Україна
2Інститут сцинтиляційних матеріалів
НАН України, Харків 61001, Україна
e-mail: mchedlov@karazin.ua
Статтю присвячено синтезу та характе-
ризації гідрозолю C70 і його коагуляції хло-
ридом натрію та бромідом цетилтриме-
тиламонію (CTAB). При концентрації C70
3.3×10–6 M електрокінетичний потенціал
дорівнює ζ = –40 ± 4 мВ, а розмір колоїд-
них частинок, виражений як Zeta-average,
M. O. Marfunin, V. K. Klochkov, P. M Radionov, N. O. Mchedlov-Petrossyan
71https://ucj.org.ua
UCJ № 10 / Vol. 87
дорівнює 97±3 нм; при концентраціях C70
1.7×10–5 і 6.9×10–5 M розмір частинок за-
лишається таким же: 99–100 нм. Значення
критичної концентрації коагуляції (CCC)
було визначено, використовуючи залеж-
ність швидкості зростання діаметру від
концентрації NaCl. Значення CCC зале-
жать від концентрації гідрозолю: вони
дорівнюють 250, 145 і 130 мM при концен-
траціях C70 3.3×10–6, 1.7×10–5 і 6.9×10–5 M,
відповідно. Значення CCC при коагуляції
за допомогою CTAB є набагато нижчим:
≈ 5×10–3 мМ. Але при концентрації CTAB
0.02 мМ спостерігаємо перезарядження
до ζ = + 40 мВ і стабілізацію колоїдних
частинок. Інтерпретація коагуляції гід-
розолю хлоридом натрію за допомогою
теорії ДЛФО робить можливим оцінку
константи Гамакера для взаємодії C70–C70
у вакуумі, AFF ≈ 7×10–20 Дж, якщо врахову-
вати тільки електростатичне відштовху-
вання та молекулярне притягання. З іншо-
го боку, якщо використовувати значення
AFF = (16.0–16.6)×10–20 J, знайдене раніше
при вивченні органозолів, тоді результат
для гідрозолю стає можливим тільки при
введенні до розгляду додаткового типу
взаємодій. Згідно з Чураєвим і Дерягіним,
треба враховувати внесок структурної
складової до загальної енергії взаємодії,
який стабілізує гідрозоль.
Keywords: гідрозоль фулерену С70, елек-
трокінетичний потенціал, хлорид натрію,
бромід цетилтриметиламонію, критична
концентрація коагуляції, теорія Дерягіна –
Ландау – Вервея – Овербека, діаграма Гама-
кера, константа Гамакера фулерен – фуле-
рен, структурний внесок у взаємодію між
частинками.
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Стаття надійшла 25.11.2021.
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| id | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-369 |
| institution | Ukrainian Chemistry Journal |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:07:06Z |
| publishDate | 2021 |
| publisher | V.I.Vernadsky Institute of General and Inorganic Chemistry |
| record_format | ojs |
| resource_txt_mv | ucjorgua/ed/e753af231ca07d9084898646b3f513ed.pdf |
| spelling | oai:ojs2.1444248.nisspano.web.hosting-test.net:article-3692026-07-22T08:23:47Z HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS Mchedlov-Petrossyan, Nikolay Marfunin, Mykyta Klochkov , Volodymyr Radionov, Petro fullerene C70 hydrosol, electrokinetic potential, sodium chloride, cetyltrimethylammonium chloride, critical concentration of coagulation, Derjaguin–Landau–Verwey–Overbeek theory, Hamaker diagram, fullerene–fullerene Hamaker constant, structural contribution to the inter-particle interaction. 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&nbsp;–&nbsp;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. V.I.Vernadsky Institute of General and Inorganic Chemistry 2021-11-26 Article Article Physical chemistry Физическая xимия Фізична xімія application/pdf https://ucj.org.ua/index.php/journal/article/view/369 10.33609/2708-129X.87.10.2021.63-73 Ukrainian Chemistry Journal; Vol. 87 No. 10 (2021): Ukrainian Chemistry Journal; 63-73 Украинский химический журнал; ##issue.vol## 87 ##issue.no## 10 (2021): Ukrainian Chemistry Journal; 63-73 Український хімічний журнал; Том 87 № 10 (2021): Український хімічний журнал; 63-73 2708-129X 2708-1281 en https://ucj.org.ua/index.php/journal/article/view/369/190 Copyright (c) 2021 Nikolay Mchedlov-Petrossyan, Mykyta Marfunin, Volodymyr Klochkov , Petro Radionov https://creativecommons.org/licenses/by-nc/4.0 |
| spellingShingle | Mchedlov-Petrossyan, Nikolay Marfunin, Mykyta Klochkov , Volodymyr Radionov, Petro HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS |
| title | HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS |
| title_full | HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS |
| title_fullStr | HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS |
| title_full_unstemmed | HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS |
| title_short | HYDROSOL OF C70 FULLERENE: SYNTHESIS AND STABILITY IN ELECTROLYTIC SOLUTIONS |
| title_sort | hydrosol of c70 fullerene: synthesis and stability in electrolytic solutions |
| topic_facet | fullerene C70 hydrosol electrokinetic potential sodium chloride cetyltrimethylammonium chloride critical concentration of coagulation Derjaguin–Landau–Verwey–Overbeek theory Hamaker diagram fullerene–fullerene Hamaker constant structural contribution to the inter-particle interaction. |
| url | https://ucj.org.ua/index.php/journal/article/view/369 |
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