Vasil'ev Sergey G, Volkov Vitaly I, Tatarinova Elena A, Muzafarov Aziz M
Institute of Problems of Chemical Physics, Academician Semenov Avenue 1, Chernogolovka, 142432 Russian Federation.
Appl Magn Reson. 2013;44(9):1015-1025. doi: 10.1007/s00723-013-0456-8. Epub 2013 May 31.
The structure of MQ copolymers of the general chemical formula [(CH)SiO] [SiO] 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. Si NMR spectra were obtained by single pulse excitation (or direct polarization, DP) and cross-polarization (CP) Si{H} techniques in concert with MAS. It was shown that material consist of monofunctional M (≡SiO (CH)) and two types of tetrafunctional Q units: Q ((≡SiO)) and Q ((≡SiO)OH). Spin-lattice relaxation times measurements of Si nuclei and analysis of Si{H} 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.
通过固态魔角旋转（MAS）核磁共振（NMR）光谱对通式为[(CH)SiO][SiO]的MQ共聚物结构进行了表征。MQ共聚物是高度支化的多环化合物（密集交联的纳米级网络）。MQ共聚物是在活性介质中通过水解缩聚制备的。通过单脉冲激发（或直接极化，DP）和交叉极化（CP）Si{H}技术与MAS协同获得Si NMR光谱。结果表明，该材料由单官能团M（≡SiO (CH)）和两种四官能团Q单元组成：Q（(≡SiO)）和Q（(≡SiO)OH）。对Si原子核的自旋晶格弛豫时间测量以及对Si{H}可变接触时间信号强度的分析使我们能够获得共聚物中不同位点相对含量的定量数据。这些研究表明，MQ共聚物代表具有核壳结构的致密结构。
