ISSN 1070-4272, Russian Journal of Applied Chemistry, 2016, Vol. 89, No. 6, pp. 930−936. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © N.Yu. Eﬁ mov, A.A. Malygin, A.A. Rychkov,
2016, published in Zhurnal Prikladnoi Khimii, 2016, Vol. 89, No. 6, pp. 771−777.
AND POLYMERIC MATERIALS
Chemical and Physical Modiﬁ cation and Electret Properties
of Polytetraﬂ uoroethylene Films
N. Yu. Eﬁ mov
, A. A. Malygin
, and A. A. Rychkov
St. Petersburg State Institute of Technology (Technical University), Moskovskii pr. 26, St. Petersburg, 190013 Russia
*e-mail: eﬁ firstname.lastname@example.org
Herzen State Pedagogical University of Russia, nab. reki Moiki 48, St. Petersburg, 191186 Russia
Received April 28, 2016
Abstract—Composites with titanium oxide structures on the surface of a polymer matrix were prepared by
preliminary plasma activation of polytetraﬂ uoroethylene ﬁ lms, followed by chemical treatment with vapors
of titanium tetrachloride and water. The chemical composition and structure of the modiﬁ ed ﬁ lm surface were
studied by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The
stability of the formed surface charge increases in going from the initial ﬁ lm to the plasma-activated ﬁ lm, then to
the ﬁ lm successively treated with vapors of titanium tetrachloride and water, and ﬁ nally to the plasma-activated
ﬁ lm treated subsequently with vapors of titanium tetrachloride and water. The modiﬁ ed polytetraﬂ uoroethylene
ﬁ lms are of interest as electrets with enhanced operation characteristics.
Modification of polymer materials allows their
functional properties (surface energy, water vapor and
gas permeability, physicomechanical and electrophysical
characteristics) to be varied in wide ranges. Among
diverse application ﬁ elds of polymer materials with the
modiﬁ ed surface, the development of electrets based on
them shows much promise .
Polymer electrets, which are sources of steady-
state electric ﬁ eld, are widely used in industry, e.g., in
production of electroacoustic converters, ﬁ lters, and
sensors. Fabrication of such items requires polymer
dielectric materials characterized by maximum possible
stability of the charge formed on their surface for a long
time in a wide temperature range .
Electret materials based on polytetraﬂ uoroethylene
(PTFE) and its copolymers have found the widest
industrial use today. Studies aimed at improvement of the
electret characteristics of these nonpolar polyﬂ uorooleﬁ ns
show that the processes of charge accumulation and
relaxation in them are largely determined by the
condition of the surface layer . Therefore, variation
of the surface layer composition of a polymer matrix by
modiﬁ cation can be one of promising ways of enhancing
the temperature and time stability of the charge of PTFE-
based electrets. The efﬁ ciency of using such approach was
demonstrated in studies [2, 3] dealing with treatment of
nonpolar ﬂ uoropolymers by molecular layer deposition
. It has been shown that titanium oxide or phosphorus
oxide structures synthesized by this method ensure
stabilization of the electret charge compared to the
unmodiﬁ ed sample.
This study was aimed at revealing the relationship
between the chemical composition and structure of the
surface of modiﬁ ed PTFE ﬁ lms, on the one hand, and their
electret characteristics, on the other hand. We intended to
evaluate experimentally the possibility of enhancing the
reactivity of the PTFE surface by its preliminary treatment
with glow discharge plasma.
The investigation objects were oriented polytetra-
ﬂ uoroethylene ﬁ lms of F-4 KO grade, made of pure
polytetraﬂ uoroethylene. The ﬁ lms had a thickness of
13 μm and were plated on one side with a thin (~50 nm)
layer of aluminum metal.