title: A Solid-State NMR Investigation of MQ Silicone Copolymers.
abstract: The structure of MQ copolymers of the general chemical formula [(CH3)3SiO0.5]m[SiO2]nwas 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 (≡SiOSi(CH3)3) and two types of tetrafunctional Q units: Q4((≡SiO)4Si) and Q3((≡SiO)3SiOH). Spin-lattice relaxation timesT1measurements of29Si nuclei and analysis of29Si{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.
authors.affiliation: Institute of Problems of Chemical Physics, Academician Semenov Avenue 1, Chernogolovka, 142432 Russian Federation.
authors.forename: Sergey G
authors.initials: SG
authors.lastname: Vasil'ev
authors.forename: Vitaly I
authors.initials: VI
authors.lastname: Volkov
authors.forename: Elena A
authors.initials: EA
authors.lastname: Tatarinova
authors.forename: Aziz M
authors.initials: AM
authors.lastname: Muzafarov
references.citation: Solid State Nucl Magn Reson. 2009 Apr;35(2):82-6
references.pmid: 19181489
references.citation: Langmuir. 2009 Sep 1;25(17):10121-33
references.pmid: 19705899