TY - JOUR
T1 - Silicon-29 cross-polarization/magic-angle-spinning NMR study of inorganic-organic hybrids
T2 - Homogeneity of sol-gel derived hybrid gels
AU - Komori, Yoshihiko
AU - Nakashima, Hiroshi
AU - Hayashi, Shigenobu
AU - Sugahara, Yoshiyuki
N1 - Funding Information:
The authors are grateful to Professor Kazuyuki Kuroda (Waseda University, Department of Applied Chemistry) for his helpful discussions. This work was financially supported in part by Waseda University as a special research project.
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2005
Y1 - 2005
N2 - The structures of sol-gel derived hybrid gels prepared by co-hydrolysis of tetraethoxysilane (TEOS)-organotrialkoxysilane (RTES, RSi(OC2H 5)3, R = CH3, C5H11, C8H17 and C6H5) mixtures (TEOS:RTES:CH3CH2OH:H2O:HNO3 = 0.5:0.5:10:x:0.3; x = 2, 5, 10 and 20) were characterized based on signal intensities of 29Si CP/MAS NMR as a function of the contact time. The contact time dependencies of the signals for Q4 (Si(OSi) 4) units were successfully simulated by assuming distributed cross relaxation times (TSiH) and an intrinsic 1H spin-lattice relaxation time in the rotating frame (T1σH); the latter was different from the apparent T1σH value estimated by assuming single TSiH. The distribution ranges of T SiH for the TEOS-RTES gels broadened as the water content increased, suggesting that the Q4 units tended to be separated from the T units and that the local concentration of 1H spins around the Q4 unit tended to decrease.
AB - The structures of sol-gel derived hybrid gels prepared by co-hydrolysis of tetraethoxysilane (TEOS)-organotrialkoxysilane (RTES, RSi(OC2H 5)3, R = CH3, C5H11, C8H17 and C6H5) mixtures (TEOS:RTES:CH3CH2OH:H2O:HNO3 = 0.5:0.5:10:x:0.3; x = 2, 5, 10 and 20) were characterized based on signal intensities of 29Si CP/MAS NMR as a function of the contact time. The contact time dependencies of the signals for Q4 (Si(OSi) 4) units were successfully simulated by assuming distributed cross relaxation times (TSiH) and an intrinsic 1H spin-lattice relaxation time in the rotating frame (T1σH); the latter was different from the apparent T1σH value estimated by assuming single TSiH. The distribution ranges of T SiH for the TEOS-RTES gels broadened as the water content increased, suggesting that the Q4 units tended to be separated from the T units and that the local concentration of 1H spins around the Q4 unit tended to decrease.
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U2 - 10.1016/j.jnoncrysol.2004.10.005
DO - 10.1016/j.jnoncrysol.2004.10.005
M3 - Article
AN - SCOPUS:10644280665
SN - 0022-3093
VL - 351
SP - 97
EP - 103
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
IS - 2
ER -