ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 8, pp. 1229−1234. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © E.S. Klimov, M.V. Buzaeva, O.A. Davydova, A.V. Isaev, K.N. Nishchev, A.A. Pynenkov, E.G. Kalashnikovc, A.N. Fomin, V.V. Svetukhin,
2015, published in Zhurnal Prikladnoi Khimii, 2015, Vol. 88, No. 8, pp. 1105−1110.
INORGANIC SYNTHESIS AND INDUSTRIAL
Changes of the Surface and Properties of Multi-Walled Carbon
Nanotubes in Physicochemical Modiﬁ cation
E. S. Klimov
, M. V. Buzaeva
, O. A. Davydova
, A. V. Isaev
, K. N. Nishchev
A. A. Pynenkov
, E. G. Kalashnikov
, A. N. Fomin
, and V. V. Svetukhin
Ul’yanovsk State Technical University, ul. Severnyi Venets 32, Ul’yanovsk, 432027 Russia
Ogarev Mordovia State University, ul. Bol’shevistskaya 68, Saransk, Mordovia, 430005 Russia
Ul’yanovsk State University, ul. L’va Tolstogo 42, Ul’yanovsk, 432017 Russia
Received July 14, 2015
Abstract—Processes of physicochemical modiﬁ cation of multi-walled carbon nanotubes in their annealing in air
and treatment with strong acids were studied. The treatment with acids functionalizes the surface of the nanotubes
via grafting of carbonyl and carboxy groups. Under the oxidative treatment, the array of nanotubes is split into
shorter fragments to give a microdispersed surface. The thermal oxidation of modiﬁ ed nanotubes occurs at lower
temperatures as compared with the untreated nanotubes. Polymethyl methacrylate and functionalized carbon
nanotubes were used to produce composite with a higher tensile strength as compared with the starting polymer.
Carbon nanotubes (CNTs) are known for their unique
mechanical, electrical, and thermal properties suitable
for a wide variety of applications in various composite
materials. In particular, introduction of minor amounts
(<1%) of nanotubes into polymers signiﬁ cantly improves
technological properties of materials and provides a high
mechanical strength and heat conductivity, comparable
with those for metals.
The practical application of CNTs meets some prob-
lems that hinder wide use of nanocarbon structures. The
incorporation efﬁ ciency of nanotubes in various compos-
ites strongly depends on their ability to be homogeneously
dispersed in the matrix without deterioration of its integ-
rity. In this regard, an important problem is posed by the
pronounced tendency of nanotubes toward agglomeration,
which creates severe difﬁ culties in introduction of CNTs
into the matrix of a material.
This problem is rather difﬁ cult and requires a complex
approach with application of various methods for homog-
enization of mixtures. In addition, the CNT surface is inert
toward chemical reagents and should be modiﬁ ed to be
made active. Physical and chemical treatment methods
are used to enhance the adhesion interaction between the
CNTs and the matrix, such as the ultrasonic dispersion
and chemical modiﬁ cation. Treatment of nanotubes with
strong oxidizing agents, with oxygen-containing polar
groups (hydroxy, carbonyl, carboxy) formed on their
surface, yields CNTs with new functional properties and
a more stable dispersed system .
The goal of our study was to perform a physicochemi-
cal modiﬁ cation of multi-walled carbon nanotubes and
examine changes occurring in the material.
The synthesis of multi-walled carbon nanotubes
(MWCNTs) was described in .
To perform all procedures, MWCNTs were preliminar-
ily ground in a metallic homogenizer. When necessary,
an ultrasonic treatment (IL 100-6/4 laboratory installation
operating at a frequency of 22 kHz) was performed in
isopropanol, with the subsequent drying at 100°C for 6 h.
Thermal treatment of MWCNTs. A 4-g portion of
CNTs was poured in to a ceramic boat and placed for