TY - JOUR
T1 - Hydrolysis behavior of a precursor for bridged polysilsesquioxane 1,4-bis(triethoxysilyl)benzene
T2 - A 29Si NMR study
AU - Saito, Hitomi
AU - Nishio, Yuki
AU - Kobayashi, Manabu
AU - Sugahara, Yoshiyuki
N1 - Funding Information:
Acknowledgments This work was financially supported in part by the Global COE Program‘‘Center for Practical Chemical Wisdom’’by MEXT, Japan. The authors wish to express their sincere thanks to Dr. Toshimichi Shibue (Materials Characterization Central Laboratory at Waseda University) for his assistance for 29Si NMR measurements.
PY - 2011/1
Y1 - 2011/1
N2 - The hydrolysis behavior of 1,4-bis(triethoxysilyl)benzene (BTB), a precursor of bridged polysilsesquioxane, was investigated with high-resolution 29Si nuclear magnetic resonance (29Si NMR) spectroscopy at ambient temperature in a system with BTB:ethanol:water:HCl = 1:10:x:0.8 × 10-4 (x = 3, 6 or 9). Signals due to hydrolyzed triethoxysilyl groups as well as unhydrolyzed triethoxysilyl groups [-Si(OEt)3, -Si(OEt)2(OH), -Si(OEt)(OH)2 and -Si(OH)3 (OEt = OCH2CH3)] formed four sub-regions based on the number of hydroxyl groups bound to a silicon atom. In addition, one silicon environment influenced the other silicon environment by an intra-molecular interaction between two silicon atoms, and each sub-region for monomeric species thus contained four signals. Based on the development of signal intensity, it is revealed that one of the two triethoxysilyl groups in BTB is hydrolyzed preferentially. Thus, when a triethoxysilyl group is hydrolyzed, the -Si(OH) x (OEt)3-x (x = 1, 2) groups formed undergo further hydrolysis, which is opposite to the tendency expected from the hydrolysis behavior of organotrialkoxysilanes under acidic conditions.
AB - The hydrolysis behavior of 1,4-bis(triethoxysilyl)benzene (BTB), a precursor of bridged polysilsesquioxane, was investigated with high-resolution 29Si nuclear magnetic resonance (29Si NMR) spectroscopy at ambient temperature in a system with BTB:ethanol:water:HCl = 1:10:x:0.8 × 10-4 (x = 3, 6 or 9). Signals due to hydrolyzed triethoxysilyl groups as well as unhydrolyzed triethoxysilyl groups [-Si(OEt)3, -Si(OEt)2(OH), -Si(OEt)(OH)2 and -Si(OH)3 (OEt = OCH2CH3)] formed four sub-regions based on the number of hydroxyl groups bound to a silicon atom. In addition, one silicon environment influenced the other silicon environment by an intra-molecular interaction between two silicon atoms, and each sub-region for monomeric species thus contained four signals. Based on the development of signal intensity, it is revealed that one of the two triethoxysilyl groups in BTB is hydrolyzed preferentially. Thus, when a triethoxysilyl group is hydrolyzed, the -Si(OH) x (OEt)3-x (x = 1, 2) groups formed undergo further hydrolysis, which is opposite to the tendency expected from the hydrolysis behavior of organotrialkoxysilanes under acidic conditions.
KW - Bridged polysilsesquioxane
KW - Hydrolysis behavior
KW - Intra-molecular interaction
KW - Si NMR
UR - http://www.scopus.com/inward/record.url?scp=79751536607&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79751536607&partnerID=8YFLogxK
U2 - 10.1007/s10971-010-2323-5
DO - 10.1007/s10971-010-2323-5
M3 - Article
AN - SCOPUS:79751536607
SN - 0928-0707
VL - 57
SP - 51
EP - 56
JO - Journal of Sol-Gel Science and Technology
JF - Journal of Sol-Gel Science and Technology
IS - 1
ER -