Poly(propylene glycols) as Effective Additives
to the Sol-Gel Process in Fabrication
of Antireflection Coatings onto Silica Glass
B. B. Troitskii
, Yu. A. Mamaev
, A. A. Babin
, V. N. Denisova
, M. A. Novikova
L. V. Khokhlova
, and T. I. Lopatina
Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Nizhni Novgorod, Russia
Institute of Applied Physics, Russian Academy of Sciences, Nizhni Novgorod, Russia
Received February 19, 2008
Abstract—Possibility of obtaining mesoporous silicon dioxide antireflection coatings with low refractive
index (1.20–1.277) by using additions of poly(propylene glycols) with various molecular masses in a sol-gel
process was examined. It was demonstrated that the optimal concentration of poly(propylene glycols) in the sol,
at which a sol-gel process followed by heating of a sample yields a transparent film with a maximum light
transmission of 98.3–99.0%, depends on the average molecular mass of the additive.
OF SYSTEMS AND PROCESSES
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 6, pp. 991–994. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © B.B. Troitskii, Yu.A. Mamaev, A.A. Babin, V.N. Denisova, M.A. Novikova, L.V. Khokhlova, T.I. Lopatina, 2009, published in
Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 6, pp. 935–938.
Multilayer coatings are widely used in blooming of
optical articles. These coatings are deposited by
vacuum techniques  and a sol-gel method [2–4].
The sol-gel method is simpler in practice and can be
used to deposit coatings onto large optical elements.
New opportunities in fabrication of antireflection
coatings are opened up by production of nanoporous
(mesoporous) silicon oxides with low refractive
indices (1.20–1.30) by modern versions of the sol-gel
technique: (1) matrix synthesis of mesoporous silicates
and aluminosilicates in the presence of surfactants [5,
6]; (2) synthesis of porous materials on the basis of
bridged polysesquioxanes ; and (3) synthesis of
mesoporous silicates in the presence of non-surfactant
organic compounds .
It has been shown previously that addition of
organic acids, derivatives of organic acids ,
carbochain polymers, statistical copolymers , and
oligoesters  to the sol-gel process results in
deposition of antireflection coatings on silicate glass.
The coatings are transparent thin films (~100 nm) that
are composed of mesoporous silicon dioxide and have
low refractive index (1.23–1.34). Silicate glass with a
double-side single-layer coating has the maximum
transmittance of 98.0–99.0% for light incident onto the
glass at an angle of 0°. Without the coating, the
maximum transmittance of this glass is only 91.0%.
The organic compounds studied [9–11] are not
surfactants or amphiphilic block-copolymers and the
sol-gel technique for deposition of mesoporous silicon
dioxide can be regarded as belonging to version (3).
The aim of this study was to examine the possibility
of deposition of mesoporous silicon dioxide
antireflection coatings with low refractive index (1.23–
1.30) by using poly(propylene glycol) oligomers with
various molecular masses in the sol-gel process.
Tetraethoxysilane (TEOS) was hydrolyzed by the
procedure described in . A 1.0-ml portion of TEOS
and 5.0 ml of isopropanol were placed in a 50-ml glass
vessel and water (in a 4 : 1 molar ratio with respect to
TEOS) and hydrochloric acid (3.0×10
mol per mole
of TEOS) were added. After the reaction mixture was
agitated with a magnetic stirrer for 1–4 h, a solution of
polypropylene glycol (PPG) in isopropanol was
introduced into the reaction mixture and it was agitated