ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 9, pp. 1570 !1574. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + A.V. Kalinin, A.P. Voznyakovskii, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 9, pp. 1537!1542.
AND POLYMERIC MATERIALS
Application of Reverse Gas Chromatography to Studying
the Microheterogeneous Structure of Block Copolymers
A. V. Kalinin and A. P. Voznyakovskii
Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia
Lebedev Research Institute of Synthetic Rubber, St. Petersburg, Russia
Received December 25, 2006; in final form, May 2007
Abstract-The mechanism of processes occurring when a low-molecular-weight compound interacts with a
block copolymer is considered. The anomalous results obtained with the butadiene3styrene stationary phase
are accounted for. The effect of modifying additives on the sorption properties of the polymer is examined.
Previously we reported on a relationship between
the nanoscopic structure of a polymer used as a sta-
tionary chromatoghraphic phase and the shape of the
retention diagram, with a newly synthesized multi-
block polyester3polysiloxane copolymer as example
. We demonstrated the potentialities of reverse gas
chromatography (RGC) furnishing important informa-
tion on the internal structure of a polymer and its
solubility (or swellability) in various low-molecular-
weight substances, using only small amounts of a
polymer sample and simple and cheap equipment.
This information allows a conclusion on whether the
given polymer is suitable for preparing items contact-
ing in the course of operation with a given solvent.
However, an attempt to confirm by RGC the exist-
ence of a complex domain nanostructure in a polymer
(butadiene3styrene) failed. The retention diagrams of
six different sorbates (n-alkanes C
methylene chloride, carbon tetrachloride) were strictly
linear, which, at first glance, contradicts the conlu-
sions made in , because specifically for butadiene3
styrene copolymer the existence of such structure was
confirmed previously in numerous studies . Here
we attempt to rationalize this paradox.
We used an installation based on an LKhM-8MD
chromatograph, described in detail previously .
As the stationary phase we used multiblock copoly-
mers of phenolphthalein terephthalate and polydimeth-
ylsiloxane with varied ratio of the rigid and flexible
blocks, both straight and modified with low-molecu-
lar-weight compounds nonvolatile under the experi-
mental conditions, as well as commercially available
butadiene3styrene copolymers DST-20 and DSSK-20.
The polyester3polysiloxane copolymers were prepared
by the procedure described in , somewhat adapted
to the available solvents. A photomicrograph of the
synthesized block copolymer was obtained with a
To clarify the situation, we compared the retention
diagrams of the same sorbate by stationary phases of
the butadiene3styrene block copolymer and the ran-
dom copolymer with the same ratio of the butadiene
and styrene units (Fig. 1). It can be readily seen that
both dependences are strictly linear, and at any tem-
perature the retention volume for the random copoly-
mer is larger than for the block copolymer.
To a first approximation, the sorption of a low-
molecular-weight probe by block copolymers, which
have a complex structure formed by nanosized do-
mains of rigid blocks distributed in a continuous
medium, can be represented as a sum of two indepen-
dent processes occurring simultaneously: dissolution
of a low-molecular-weight probe in the interdomain
dispersion medium and its adsorption on the surface
of domains of the [rigid] phase. Then the specific
retention volume of a sorbate on the stationary phase
) is equal to 
= S + A, (1)
where S is the contribution made by dissolution of
sorbate molecules in the dispersion medium, and A,
adsorption contribuition, A = K
, where K