Bridge Polysilsesquioxane Xerogels with a Bifunctional Surface Layer of the 
Si(CH2)3NH2/
Si(CH2)3SH Composition
N. V. Stolyarchuk*, I. V. Mel’nik, Yu. L. Zub*, M. Barczak**, A, Dabrowski**, and B. Alonso***
*Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine,
ul. Generala Naumova 17, Kiev, 03164 Ukraine
**Faculty of Chemistry, University of Maria Curie-Sklodowska, Pl. M. Curie-Sklodiwskiej 3, Lublin, 20-031 Poland
***Institute Charles Gerhardt – UMR 5253 (CNRS/ENSCM/UM2/UM1) 8, rue de l’Ecole Normale,
Montpellier cedex 5, 34296 France
Received June 5, 2008
Abstract — Xerogels with a bifunctional surface layer of the 
Si(CH2)3NH2/Si(CH2)3SH composition are synthesized by hydrolytic co-polycondensation of bis(triethoxy)silane (C2H5O)3Si(CH2)2Si(OC2H5)3 and two trifunctional silanes, namely, 3-aminopropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane. Using IR, 1HMAS NMR, and 13C CP/MAS NMR spectroscopic techniques, it is shown that in addition to complexing groups, the surface layer also contains water, silanol groups that are involved in the hydrogen bond formation and also residual ethoxysilyl groups. According to 29SiCP/MAS NMR spectroscopic data, the degree of polycondensation of synthesized xerogels exceeds 80%. It is found that the use of 1,2-bis(triethoxysilyl)ethane as the structuring agent in place of tetraethoxysilane allows one to synthesize bifunctional xerogels with the highly developed biporous structure (Ssp = 607–680 m2/g, Vc = 1.38–1.47 cm3/g, d = 2.9–3.1 and 18.3 nm). Changing the ratio structuring-silane/functionalizing-silane-mixture from 2 : 1 to 4 : 1 in the reaction system has virtually no effect on the porous structure parameters of final xerogels.
Si(CH2)3NH2/Si(CH2)3SH composition are synthesized by hydrolytic co-polycondensation of bis(triethoxy)silane (C2H5O)3Si(CH2)2Si(OC2H5)3 and two trifunctional silanes, namely, 3-aminopropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane. Using IR, 1HMAS NMR, and 13C CP/MAS NMR spectroscopic techniques, it is shown that in addition to complexing groups, the surface layer also contains water, silanol groups that are involved in the hydrogen bond formation and also residual ethoxysilyl groups. According to 29SiCP/MAS NMR spectroscopic data, the degree of polycondensation of synthesized xerogels exceeds 80%. It is found that the use of 1,2-bis(triethoxysilyl)ethane as the structuring agent in place of tetraethoxysilane allows one to synthesize bifunctional xerogels with the highly developed biporous structure (Ssp = 607–680 m2/g, Vc = 1.38–1.47 cm3/g, d = 2.9–3.1 and 18.3 nm). Changing the ratio structuring-silane/functionalizing-silane-mixture from 2 : 1 to 4 : 1 in the reaction system has virtually no effect on the porous structure parameters of final xerogels.
PACS numbers: 68.43.-h
DOI: 10.1134/S2070205109020075