Ian Wark Research Institute
ARC Special Research Centre
ARC Special Research Centre
Research Area: Polymer science
Degree: Honours
Supervisor: Prof Namita Roy Choudhury
Description: In-situ formation of inorganic fillers in organic polymeric matrixes is important in the preparation of composite materials whereby the finally dispersed filler particles act as a reinforcing agent to enhance the mechanical properties1-3. A miscible sol will be added to the organic polymer, which can then be easily converted to non-aggregating and small (eg sub-micron) gel particles. Reinforced polymers are obtained provided the continuous phase remains the polymeric matrix with the gel particles embedded in it.
The aim of this research proposal is to introduce a novel and practical approach that retains the advantages inherent to in-situ sol-gel transformation of a filler precursor in polysiloxane without the disadvantages of the hydrolysis processes.
The proposed approach retains the advantages of the sol-gel method whereby the precursor filler is incorporated into the polymer matrix easily, avoiding the energy intensive mixing of agglomerated silica fillers and degradation of the polymer chain due to excessive shear. In our proposed approach the filler precursor is a liquid and its viscosity can be controlled by the preparation method. Furthermore, it is compatible with the polysiloxane matrix and thus can easily be blended to yield a homogeneous composition. Thus, it is expected that the composite will have excellent mechanical properties at least as good and probably better that those observed in composites prepared by the sol-gel method. Since the filler precursor is a liquid, there are no health issues associated with handling and processing, as is the case with fine silica particles.
The proposed research consists of the following steps:
- hydrolysis of vinyltrimethoxysilane to vinylsilsesquioxane
- incorporation of vinylsilsesquioxane into PDMS
- ozonation of the vinylsesquioxane/PDMS blend
- vulcanization of the silica/PDMS composite to yield reinforced elastomers
- testing and characterization of the elastomer composites.
References
1) BB Boonstra, Polymer, 20, 691 (1979).
2) F Sndvet, TM Lam, J-P Pascanlt, C Mai, Macromolecules, 25, 5742 (1992).
3) AS Hashim, S Kohjiya, Y Ikeda, Polym. Int.. 38, 111 (1995).
