1070-4272/03/7611-1864$25.00C2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 11, 2003, pp. 1864!1866. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 11,
2003, pp. 1915!1917.
Original Russian Text Copyright + 2003 by Airapetyan, Khachatryan.
Chromatographic Properties of Silica Gel Packing Materials
as Influenced by Polymeric Coating
S. S. Airapetyan and A. G. Khachatryan
Yerevan State University, Yerevan, Armenia
Received December 3, 2002; in final form, May 2003
Abstract-Some chromatographic properties of microspheric silica gels coated with copolymer of poly-
styrene, p-divinylbenzene, and allyl alcohol were studied. The measurements were performed by reverse-phase
high-performance liquid chromatography using modified C
phases with secondary silanization with
Development of new procedures improving struc-
tural and chromatographic parameters of packing
materials for chromatographic columns, including
silica gel, remains urgent. At present, it seems impos-
sible to propose a principally novel process for prepar-
ing packing materials based on silica gel for high-per-
formance liquid chromatography (HPLC) to meet all
the chromatographic requirements. Therefore, another
approach is preferred: modification of known systems,
e.g., coating of the silica gel surface with a polymeric
material. As a result, systems exhibiting the properties
of both silica gel and coating polymer are obtained.
This can decrease or even completely eliminate the
solubility of silica gel, making it applicable in aque-
ous and, especially, in alkaline aqueous solutions.
Several procedures are used to deposit polymeric
layers on silica gel supports , macroporous
glasses [12, 13], and diatomite . Coating of non-
silica gel supports (e.g., aluminum oxide, zirconium
dioxide, and carbon glass) with polymeric layers is
described in . For this purpose, both natural [3, 4,
10, 11] and synthetic [1, 2, 539, 12315] polymers are
In some works on polymeric coatings, primary
attention is given to covalent binding of the polymeric
coating with a support surface . At the same
time, it is believed  that there is no pronounced dif-
ference between systems with polymeric coatings
bound to the support surface and encapsulating this
In this work we studied the possibility of improv-
ing some chromatographic properties of packing ma-
terials based on silica gel microspheres by their coat-
ing with an appropriate polymer.
As starting materials for column packing we used
microspheric silica gels (MSs) prepared by hydro-
thermal modification of the initial MS, which, in turn,
was obtained by the procedure given in .
The modes of hydrothermal treatment (HT) of the
initial MS for preparing macroporous samples and the
pore properties of the resulting silica gels are listed in
Table 1. The size distribution of these MSs are shown
in the figure.
The polymeric layer was applied to MS by poly-
merization of an adsorption layer of the monomer
mixture in the presence of benzoyl peroxide (BP),
whose content was about 335 wt % of the total weight
of monomers. The porous support was impregnated
with a solution of the monomer mixture in acetone
with subsequent removal of the solvent at room tem-
perature. The polymerization initiator PB was added
simultaneously with the monomers, providing poly-
Table 1. Preparation conditions and porosity character-
istics of microspheric silica gels*
Mode of hydrothermal treatment ³Porosity characteristics
t,h³ pH ³T, oC ³SiO
3 ³ 3 ³ 3 ³ 3 ³ 250 ³ 0.58
2 ³ 7.5 ³ 100 ³ 1:12 ³ 230 ³ 0.58
2 ³ 8.0 ³ 120 ³ 1:12 ³ 120 ³ 0.58
2 ³ 8.0 ³ 150 ³ 1:12 ³ 75 ³ 0.58
4 ³ 8.0 ³ 200 ³ 1:12 ³ 45 ³ 0.58
*(S) Specific surface area and (V) pore volume.
** Weight ratio.