Polysiloxane formation in a tetraethoxysilane (TEOS)-ethyl alcohol (EtOD(H))-oxalic acid (OA) system without the addition of water was investigated by 29Si nuclear magnetic resonance spectroscopy (29Si-NMR). In the system with TEOS:EtOD(H):OA = 1:6:1, considerable amounts of linear oligosiloxanes possessing only ethoxy groups formed, and (EtO)3SiOSi(OEt)3, (EtO)3SiOSi(OEt)2OSi(OEt)3, and (EtO)3Si(OSi(OEt)2)2OSi(OEt)3 were identified. When the amount of OA increased to TEOS:EtOD(H):OA = 1:6:2, the polymerization rate increased considerably. The observed Si-species scarcely possessed hydroxyls, suggesting unique siloxane formation in this system.
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