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Updated: May 9, 2026

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
A Solid-State NMR Investigation of MQ Silicone Copolymers
Sergey G Vasil'ev1, Vitaly I Volkov, Elena A Tatarinova
1Institute of Problems of Chemical Physics, Academician Semenov Avenue 1, Chernogolovka, 142432 Russian Federation.
Abstract:
The structure of MQ copolymers of the general chemical formula [(CH3)3SiO0.5]m [SiO2]n was characterized by means of solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The MQ copolymers are highly branched polycyclic compounds (densely cross-linked nanosized networks). MQ copolymers were prepared by hydrolytic polycondensation in active medium. 29Si NMR spectra were obtained by single pulse excitation (or direct polarization, DP) and cross-polarization (CP) 29Si{1H} techniques in concert with MAS. It was shown that material consist of monofunctional M (≡SiO Si (CH3)3) and two types of tetrafunctional Q units: Q4 ((≡SiO)4Si) and Q3 ((≡SiO)3SiOH). Spin-lattice relaxation times T1 measurements of 29Si nuclei and analysis of 29Si{1H} variable contact time signal intensities allowed us to obtain quantitative data on the relative content of different sites in copolymers. These investigations indicate that MQ copolymers represent dense structure with core and shell.
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