ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 4, pp. 668!671. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + L.B. Yakimtsova, E.L. Egorova, E.A. Murashko, Yu.I. Matusevich, A.P. Polikarpov, L.P. Krul’, 2008, published in Zhurnal
Prikladnoi Khimii, 2008, Vol. 81, No. 4, pp. 632! 635.
AND POLYMERIC MATERIALS
Thermomechanical Properties and Heat Resistance
of Copolymers of Methyl Methacrylate with Acrylic Acid
L. B. Yakimtsova, E. L. Egorova, E. A. Murashko, Yu. I. Matusevich,
A. P. Polikarpov, and L. P. Krul’
Belarussian State University, Minsk, Belarus
Research Institute of Physicochemical Problems, Belarussian State University, Minsk, Belarus
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received June 18, 2007
Abstract-Copolymers with a mole fraction of acrylate units of 0.20 to 0.69 were prepared by radical
copolymerization of methyl methacrylate with acrylic acid. The heat resistance and thermomechanical prop-
erties of copolymer films formed from dimethylformamide solution were evaluated, and the possibilities of
improving these characteristics were demonstrated.
Thanks to high light transmittance, polymeric com-
pounds based on poly(methyl methacrylate) (PMMA)
are widely used in optical systems for information re-
cording, but their applicability is restricted by the rela-
tively low glass transition and flow points of methyl
methacrylate (MMA) polymers and the insufficient ad-
hesion of the material to silicate glasses. In this con-
text, an urgent problem is modification of PMMA pro-
perties with the aim to improve its thermomechani-
cal properties and enhance the heat resistance and ad-
hesion, with preservation of the optical transparency.
It has been found previously [1, 2] that materials with
the required characteristics can be obtained by radical
copolymerization of MMA with acrylic acid (AA).
However, the dependence of the properties of the co-
polymers (CPs) on their composition has not been
In this study we examined how the composition of
MMA3AA copolymers affects their thermal properties.
Radical copolymerization in the bulk was per-
formed in a nitrogen flow at 60oC for 4 h in a glass
test tube equipped with a reflux condenser . The
AA : MMA molar ratio was varied from 1 : 4 to 4 : 1.
As initiator we used 2,2`-azobis(isobutyronitrile).
After the synthesis completion, the polymer sample
was ground and washed at room temperature with
water and ethanol to remove the unchanged monomers
and a part of AA homopolymer. Then the sample was
dried and dissolved in dimethylformamide (DMF).
The solution was passed through a glass frit, after
which the copolymerization product was precipitated
from the solution into water. A small amount of
PMMA, which is insoluble in DMF, remained on
the filter. The AA homopolymer remained in the CP
precipitant. The CP composition was determined by
acid3base titration of carboxy groups in organic solv-
Poly(methyl methacrylate) and polyacrylic acid
(PAA) were prepared under the same conditions as
the MMA3AA copolymer. The molecular weights
(MW) of PMMA and PAA were determined viscom-
etrically in trichloromethane at 25oC(K = 0.48 0 10
a = 0.80; MW = 3.85 0 10
) and in water at 30oC
(K = 7.6 0 10
, a = 0.5; MW = 1.62 0 10
tively. To estimate the lengths of molecular chains in
CPs of various compositions at 25oC, we measured
the specific viscosities of their 0.5% solutions in
a common solvent, acetic acid.
The thermal properties of the CPs were studied
using film samples prepared from DMF solutions. Be-
cause of the high adhesion to glass, the films could
not be detached from glass supports. Therefore, when
preparing film samples for studying the thermal prop-
erties of the CPs, we used as supports polypropylene