1070-4272/04/7705-0820C2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 5, 2004, pp. 820!825. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 5,
2004, pp. 825!830.
Original Russian Text Copyright + 2004 by Sidorovich, Praslova, Novoselova, Zgonnik.
AND POLYMERIC MATERIALS
Dilatometric Characteristics of Polyacrylonitrile
in a Mixture with Fullerene C
A. V. Sidorovich, O. E. Praslova, A. V. Novoselova, and V. N. Zgonnik
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Received January 9, 2004
Abstract-Thermal cyclization of polyacrylonitrile, synthesized by anionic and radical polymerization,
in films containing 0.5 wt % fullerene C
and without it was studied dilatometrically in the range 203400oC.
Fullerenes are a family of polyhedral molecules
with a closed large-diameter spherical structure built
from three-coordinate carbon atoms with an extended
p-electron system capable of diverse interactions with
molecules of inorganic and organic substances .
This made fullerenes a subject of active studies aimed
to elucidate their promise for modification of the
properties of polymers.
acts as inhibitor in thermal and ther-
mooxidative degradation of polymethyl methacrylate
[43 6]. Calorimetric studies revealed enhanced thermal
stability of complex and covalent compounds of poly-
mers of N-vinylpyrrolidone and ethylene glycol with
[7, 8]. Much attention has been given to studying
the properties of polymers containing fullerene C
solutions [9, 10].
There are virtually no published data concerning
the influence of C
on dilatometric characteristics of
polymers under physicochemical transformations,
despite scientific and practical importance of this
In this work we studied dilatometrically the ther-
mal cyclization of polyacrylonitrile (PAN) films, with
and without fullerene C
, as influenced by the meth-
od of synthesis (anionic and radical polymerization)
and by the chemical and supramolecular structure of
PAN. This is urgent in view of the fact that heat treat-
ment of PAN is essential for preparation of high-
modulus heat-resistant fibers, as well as of semicon-
ductor and carbon materials .
We studied films prepared from PAN with M
Da, synthesized by anionic (A-PAN) and radi-
cal (R-PAN) polymerization. Anionic polymerization
was carried out in DMF at 360oC using lithium alkox-
ide , and radical polymerization, by conventional
procedure in water at 25oC in the presence of potas-
sium peroxosulfate and NaHSO
. Films of A-PAN
exhibited a narrow MWD (M
= 1.3), microtac-
ticity with a block structure coefficient K ~ 1.57 ,
and virtually perfect chemical structure of the chain
due to the lack of side reactions in the case of anionic
polymerization . Films of R-PAN exhibited a
wide MWD (M
; 10) and no microtacticity
(K ~ 1.02) .
To elucidate the influence of C
on the properties
of PAN, we took a small amount of C
, since it is
known  that the properties of polymers are most
strongly affected by the monomeric form of C
which is the most abundant at low concentrations.
The films were cast from solutions of polymers
(5 wt %) and their mixtures with fullerene (0.5 wt %
with respect to PAN) in DMF containing the desired
amount of N-methylpyrrolidone (MP) as solvent for
. The solutions were heated for 1 h at 100oC. After
filtration and cooling to room temperature, these
solutions, without preliminary keeping, were used for
casting R-PAN and A-PAN films onto glasses.
films were cast
after keeping the solutions at room temperature for
3 days. Prolonged maturing of the solution favored
structuring and improved the mechanical properties.
The films cast without preliminary keeping were
brittle, virtually unsuitable for cutting out samples
for measurements. The films were dried at room tem-
perature for 5 days.
Dilatometric measurements were carried out on an
installation capable of recording the changes in the
longitudinal linear dimensions of films accurately to