ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 3, pp. 461! 465. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + A.A. Rychkov, S.A. Trifonov, A.E. Kuznetsov, E.A. Sosnov, D.A. Rychkov, A.A. Malygin, 2007, published in Zhurnal Prikladnoi
Khimii, 2007, Vol. 80, No. 3, pp. 463! 467.
Influence of Chemical Modification of the Surface
of Low-Density Polyethylene on Its Electret Properties
A. A. Rychkov, S. A. Trifonov, A. E. Kuznetsov, E. A. Sosnov,
D. A. Rychkov, and A. A. Malygin
St. Petersburg State Institute of Technology (Technical University), St. Petersburg, Russia
Herzen Russian State Pedagogical University, St. Petersburg, Russia
Received June 29, 2006; in final form, October 2006
Abstract-The electret properties of low-density polyethylene with phosphorus-containing surface nanostruc-
tures were examined.
As known , when irradiated with charged par-
ticle (ion, electron) fluxes, polymer dielectrics ac-
cumulate a charge on their surface to form an electret
state. The charged state of such materials, which are
termed electrets, can be preserved for a fairly long
time (years). This finds wide application in modern
high technologies, in particular, in the development of
electroacoustic transformers and sensors, as well as of
nonlinear-optics components . Of great practical
importance for such systems is the stability of the
In our previous studies [3, 4] we showed that the
stability of the electret charge in polytetrafluoroethyl-
ene (PTFE) films is substantially enhanced by chemi-
cal modification of the surface with phosphorus tri-
chloride vapor. Therefore, it is of interest to examine
the electret properties of other modified polyolefins,
in particular, such commercially significant material
as low-density polyethylene (LDPE). In this connec-
tion, we examined here the electret properties of
LDPE as influenced by chemical modification of its
surface with phosphorus trichloride vapor.
This study was underlain by the following con-
(1) The electret state in nonpolar polymers is de-
termined not only by the charge capture sites in the
bulk but also, to a significant extent, by the localized
states on the surface .
(2) Surface modification of nonpolar polymers
enables directed formation in such materials of surface
deep energy wells acting as charge capture sites able
of efficiently retaining the electret charge .
(3) An efficient way of polymer surface modifica-
tion is the chemical nanotechnology based on the
molecular layer deposition principles . This tech-
nology enables incorporation of element-containing
nanostructures into surface macromolecules in a con-
trollable manner, thereby controlling the physico-
chemical, in particular, electret, properties of poly-
mers [3, 4].
Polymer films, 40 0 20 0 0.14 mm in size, were
chemically modified in a flow reactor by successive
treatment of the substrate with PCl
by molecular layer deposition. For conditions of syn-
thesis of phosphorus-containing structures on the
polymer matrix surface, see .
The samples for electret measurements were pre-
pared in the form of planar metal3polymer structures,
whose basis was a 95-mm-thick St.3 steel substrate.
A polymeric layer of the LDPE film, unmodified or
modified with phosphorus trichloride, was fixed on
the substrate surface by the thermal fitting method .
We used extrusion films of 10 203-003 brand poly-
ethylene manufactured in Russia in accordance with
GOST (State Standard) 16 337370. This polymer has
acceptable dielectric characteristics for producing
corona electrets, namely, low values of dielectric per-
mittivity (2.2 at a frequency of 1 MHz), dielectric dis-
persion, and dielectric loss tangent (2.7 0 10
a frequency of 1 MHz).
Thermal fitting was carried out at 170oC for 60 s; it
was followed by cooling in air to room temperature