NMR investigations on a liquid-crystalline side-chain siloxane polymer with a wide biphasic region
✍ Scribed by Günter Hempel; Heiko Hänsge; Bernd Metzner; Bernd Krücke
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 776 KB
- Volume
- 196
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
A polysiloxane bearing two different kinds of side chains has been studied by nuclear magnetic resonance and relaxation investigations. Both side chains contain the same mesogenic core but differ in their connection to the main chain: one of them is bound directly to the backbone, the other is linked to it via a -(CH2)3-spacer. In this sample, the isotropic and mesomorphic phases coexist over a relatively wide range of temperatures. We have tried to explain this phenomenon by microphase separation. For the sA -sB transition a similar biphasic behaviour could not be observed with our methods. The order parameter has been estimated selectively for carbons in different parts of the side chain (spacer, wing group, mesogenic core). The behaviour of the order parameter in the mesomorphic regions of the biphase was observed, and a possible explanation is given.