ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 8, pp. 1338!1340. + Pleiades Publishing, Inc., 2006.
Original Russian Text + S.I. Gusev, S.D. Zaitsev, Yu.D. Semchikov, O.G. Zakharova, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79,
No. 8, pp. 1350!1352.
AND POLYMERIC MATERIALS
A Method for Determining the Molecular Weight
of Hyperbranched Polymers
S. I. Gusev, S. D. Zaitsev, Yu. D. Semchikov, and O. G. Zakharova
Lobachevsky State University, Nizhni Novgorod, Russia
Received November 3, 2005; in final form, April 2006
Abstract-A method for determining the molecular weight of hyperbranched polymers is developed, based
on the measurement of the area of the monolayer at the water/air interface.
Intensive studies in the area of dendrimers and
hyperbranched polymers, which include applied re-
search and are generally interdisciplinary (macro-
molecular chemistry3catalysis, macromolecular chem-
istry3medicine, etc.), have created a need for develop-
ing fairly simple and efficient methods for measur-
ing molecular weights, similar to the viscometry in
the case of linear polymers. A possible way is to
measure the area of a close-packed monomolecular
layer of rigid-spherical hyperbranched or dendritic
macromolecules, using the Langmuir film balance.
The goal of this study was to develop a method for
determining the size of macromolecules, as applied
to hyperbranched dendritic polymers, poly(perfluoro-
phenylenegermane) and poly(methyldiallylsilane).
Poly(perfluorophenylenegermane) (PPG) was among
the first hyperbranched dendritic polymers prepared
by a single-stage synthesis from the Flory monomer
[tris(pentafluorophenyl)germane (PG)] [1, 2].
The units of this polymer consist of perfluorinated
aromatic rings bonded to the germanium atom, C
Ge, the latter being terminal. The ratio be-
tween units of these types is 1 : 2 , which corre-
sponds to a regular branched structure with the for-
(Fig. 1). Starting from
the third generation, the shape of the macromolecules
is nearly spherical, which is supported by the sed-
imentation data obtained with an ultracentrifuge .
The polymer demonstrates high heat resistance and
clearly pronounced antifriction properties .
PPG was synthesized as follows. To a solution of
1 g of PG in 10 ml of a solvent, the estimated amount
of triethylamine in THF was added with stirring over
a period of 5 min, and the reaction mixture was fur-
ther stirred for 5 h at 25oC. The yield was 75385%,
and increased with [Et
N] : [PG] ratio. The resulting
PPG was purified by twofold reprecipitation from
THF with methanol and then vacuum-dried to con-
stant weight. We obtained three PPG samples with
Fig. 1. (a) Chemical graph of the first to third generations
and (b) scaled chemical model of hyperbranched PPG of
the third generation.