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Published on: March 8, 2019
Viscoelastic and structural properties of a phenyl-modified polysiloxane system with a three-dimensional structure
Hiroshi Kakiuchida1, Masahide Takahashi, Yomei Tokuda
1Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan. h.kakiuchida@aist.go.jp
The Journal of Physical Chemistry. B
|April 8, 2006
Summary
This study reveals that polysiloxane network structures influence viscosity. Introducing phenyl groups reduces viscosity
Area of Science:
- Materials Science
- Polymer Chemistry
- Physical Chemistry
Background:
- Polysiloxane networks are crucial in materials science.
- Understanding their viscoelastic and structural properties is key for material design.
- Phenyl groups act as network terminators in these systems.
Purpose of the Study:
- To investigate the relationship between viscoelastic properties and the structure of glass-forming polysiloxanes.
- To understand the role of polysiloxane bonds and phenyl groups in network formation.
- To analyze the early stages of the network-forming process.
Main Methods:
- Shear viscoelasticity measurements
- (29)Si Magic Angle Spinning Nuclear Magnetic Resonance ((29)Si MAS NMR) spectroscopy
- Gel Permeation Chromatography (GPC) analysis
Main Results:
- Viscosity was frequency-independent up to 200°C, indicating no intermolecular entanglement.
- The polysiloxane system exhibits a complex structure with a distribution of molecule sizes.
- Molecular size and intramolecular structure, based on the free-volume model, determine viscosity and its temperature dependence.
Conclusions:
- The elementary process of viscosity is the simple flow of molecules.
- Larger numbers of phenyl groups decrease the viscosity's sensitivity to structural factors.
- Quantitative examination links viscosity to structure around the glass transition temperature.
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