1070-4272/01/7407-1173$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 7, 2001, pp. 1173!1177. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 7,
2001, pp. 1142!1147.
Original Russian Text Copyright + 2001 by Pavlyuchenko, Primachenko, Khaikin, Ivanchev, Jones.
AND POLYMERIC MATERIALS
Segregation of Polymers in the Course of Film Formation
from a Mixture of Latexes
V. N. Pavlyuchenko, O. N. Primachenko, S. Ya. Khaikin,
S. S. Ivanchev, and M. E. Jones
St. Petersburg Branch, Institute of Catalysis, Siberian Division,
Russian Academy of Sciences, St. Petersburg, Russia
Dow Chemical, the United States
Received February 8, 2001
Abstract-Film formation from binary mixtures of latexes of thermodynamically incompatible polymers was
studied. Partial segregation of the polymers in the course of latex film formation, causing asymmetry of the
resulting films, was proved by IR Fourier spectroscopy. The influence of various factors on the segregation
of polymers was examined.
Film preparation from a mixture of two latexes of
thermodynamically incompatible polymers can result
in formation of various structures. The extreme cases
of such structures are (1) uniform distribution of par-
ticles of one polymer in the matrix of the other poly-
mer and (2) total segregation of the two polymers.
It is clear that both these cases are idealized. Never-
theless, even a tendency to predominant formation of
one or another structure creates prerequisites for solu-
tion of many applied problems.
Of particular interest are latex films in which the
polymeric components undergo segregation in the
course of film formation from a mixture of two lat-
exes. Such films, often termed asymmetric films,
owing to different chemical composition of the sur-
faces can find diverse applications: films with an ad-
hesive layer, films with increased surface hardness
and high adhesion to the substrate, films with in-
creased surface electrical conductivity, films with in-
creased hydrophobicity or hydrophilicity, etc. Usually
latex films of such kind are prepared by successive
immersion of a substrate in two different latexes,
with intermediate drying of the film after each immer-
sion . Preparation of an asymmetric film from a
mixture of latexes by a single immersion cycle is a
more promising process.
Numerous studies  showed that the polymers
are distributed nonuniformly across the film prepared
from a mixture of latexes. Okubo et al. [2, 3] suggest
that formation of asymmetric films may be due to dif-
ferent sedimentation rate of particles of different size.
Sedimentation stability of latexes is only one of the
factors affecting preparation of asymmetric films. In
this study we attempted to reveal the role of other
factors, such as, e.g., aggregative stability of latexes
and the capability of polymers for specific interactions
with a substrate on which the film is formed.
Two types of latexes, poly-n-butyl acrylate and
styrene3n-butyl acrylate (ST3BA) copolymer, were
prepared with the aim to examine the influence of
various factors on the film formation from latex mix-
tures. Usually synthesis was performed in two stages.
In stage 1 we prepared a seeding latex by charging
to the reactor a small amount of the monomers and
(co)polymerizing them to complete conversion. In
stage 2 the monomers were added gradually, and the
process was performed in the semicontinuous mode.
Emulsion copolymerization was performed in 250-
or 500-ml flasks equipped with a reflux condenser,
a stirrer, a dropping funnel for adding monomers, and
a nipple for feeding nitrogen. The following chemicals
Monomers, styrene (ST) and n-butyl acrylate (BA),
were vacuum-distilled; their characteristics agreed
with the reference data.
Initiators [potassium persulfate (PP), azobis(iso-
butyronitrile (AIBN), and 2,2`-azobis(2-amidinoprop-
ane) dichloride (AAPDC)] were used without addi-