Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 11, pp. 1952−1957.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © S.S. Ishchenko, V.L. Budnitskaya, E.V. Lebedev, N.V. Kozak, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 11,
AND POLYMERIC MATERIALS
Hybrid Composites Based
on Organic-Inorganic Sol-Gel Systems
S. S. Ishchenko, V. L. Budnitskaya, E. V. Lebedev, and N. V. Kozak
Institute of Chemistry of Macromolecular Compounds, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received November 23, 2010
Abstract—Hybrid organic-inorganic composites were developed on the basis of sodium silicate modiﬁ ed with
ε-caprolactam or ε-aminocaproic acid and isocyanate-containing oligourethane with improved physicomechanical
properties and water resistance.
At present, the most widely used method for obtain-
ing hybrid organic-inorganic composites (OICs) is the
sol-gel technique [1–3]. The authors of [4, 5] suggested
an alternative method for producing OICs by joint po-
lymerization of organic oligomers with inorganic poly-
mers, such as silicates and silicopolyphosphates. In this
case, properties of OICs can be widely varied by select-
ing the organic and inorganic constituents of the system
and conditions of the polymerization process [4–7]. In
the course of formation of hybrid systems of this kind,
functional groups of the constituents interact, which
yields composites with properties uncharacteristic of the
starting components [7, 8].
Properties of alkali metal silicates are commonly
controlled by using various modifying additives [9–11].
In the present study, we used sodium silicate modiﬁ ers
of acid-base type, which diminish the alkalinity of
silicate solutions and raise the silica ratio.
The goal of our study was to create hybrid OICs
on the basis of sodium silicate (SS) modiﬁ ed with
ε-caprolactam (CL) or ε-aminocaproic acid (ACA) and
isocyanate-containing oligourethane with improved
physicomechanical properties and water resistance.
As objects of study were used products formed in
interaction of CL- or ACA-modiﬁ ed sodium silicate
with isocyanate-containing urethane at various ratios
between the starting components.
Sodium silicate had a silica ratio of 2.85 ± 0.5 (silica
ratio is that between the amounts of SiO
). The content of free water in SS was 60 ± 3 wt %.
SS was modiﬁ ed with aqueous solutions of CL (360 g
of CL per 100 g of water) or ACA (66.6 g of ACA per
100 g of water) by introduction of various amounts of
a modiﬁ er (in moles) with respect to NaOH contained
in SS. SS + CL and SS + ACA mixtures at NaOH :
modiﬁ er (mol : mol) ratios in the range from 1 : 0.001
to 1 : 3 were studied. The mixtures were kept for ﬁ ve
days, being agitated and their viscosity, pH value, and
silica ratio being determined at regular intervals of time.
It was found that the mixtures are visually homogeneous
at NaOH : modiﬁ er ratios of up to 1 : 0.5. With increasing
amount of amino compounds, the mixtures formed to
layers, liquid and gel. In modiﬁ cation of SS with CL
or ACA, the pH of the mixtures somewhat decreased,
compared with the starting SS (from 12.3 to 11.65). The
silica ratio of SS tended to increase upon addition of
modiﬁ ers, without additives its value was m
At NaOH : modiﬁ er ratios of 1 : 0.5, 1 : 1, 1 : 1.5, and
1 : 3, the silica ratios were 2.99, 3.11, 3.13, and 3.15,
OICs were synthesized from a macrodiisocyanate
(MDI) based on polyoxypropylene glycol (MM 1052)
and toluylene diisocyanate (mixture of isomers: 2,4
65% and 2,6 35%). The MDI contained 6 ± 0.5% NCO