TY  - JOUR
A1  - Itoh, Maki
A1  - Oka, Fukuyo
A1  - Suto, Michitaka
A1  - Cook, Simon D.
A1  - Auner, Norbert
T1  - Characterization and some insights into the reaction chemistry of Polymethylsilsesquioxane or methyl silicone resins
T2  - International journal of polymer science
N2  - Structural characterization of a polymethylsilsesquioxane (PMSQ) and a DT-type methyl silicone resin (MeDT) has been carried out by various instrumental analyses including GPC, NMR, gas chromatography, and gas chromatography-mass spectrometry. Although the PMSQ had a Mw around 5000, the resin contained a significant amount of low molecular weight species consisting of T2 [MeSi(OH)O2/2] and T3 [MeSiO3/2] units, ranging from T34T23 to T38T22 including many isomers. One isomer of T36T22 was isolated of which structure was determined as a cage structure. The species are supposed to consist mainly of cyclotetra- and cyclopentasiloxanes, but presence of strained rings such as cyclotrisiloxane rings also was suggested. In MeDT, species in which the T2 units in the molecules from PMSQ is replaced with D2 [Me2SiO2/2] were found, for example, T36D22, suggesting that general silicone resins consist of similar structures as silsesquioxanes. The Mark-Houwink exponent for these methyl resins was ~0.3, indicating the molecular shape to be compact. Investigation on the formation chemistry of the cubic octamers indicates that siloxane bond rearrangement is an important mechanism in the molecule build-up process.
Y1  - 2017
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/44207
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-442072
SN  - 1687-9430
SN  - 1687-9422
N1  - Copyright © 2012 Maki Itoh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
VL  - 2012
IS  - Art. 526795
SP  - 1
EP  - 17
PB  - Hindawi
CY  - New York, NY
ER  -