|Alexander von Humboldt-Stiftung: Molecular Design and Synthesis of Novel Hyperbranched Polyborosilazane Precursors|
|Von 01/2010 bis 12/2010|
|Projektleiter: Axel H. E. Müller|
|Mitarbeiter: Jie Kong|
This project addresses the molecular design and synthesis of novel hyperbranched polyborosilazane ceramic precursors that possess advantageous characteristics of low viscosities, favorable solubilities, and enhanced pyrolysis properties. The preliminary application on preparing SiBCN ceramic matrix composites will also be investigated. Four topics are presented: (i) The molecular design and synthesis of hyperbranched polyborosilazanes via ABg (g≥2), “AA*+B3” and “A2+BB2*” monomer routes. Based on characterizations by NMR, SEC, MALLS and MALDI-TOF, key factors for regulating the macromolecular structure in the synthesis process will be studied. (ii) The relationship between hyperbranched structures and solutions, intrinsic viscosity and rheological properties of the as-synthesized polymers. (iii) The pyrolysis properties of hyperbranched polyborosilazanes. Through investigations by positron annihilation life-time spectroscopy (PALS) and TGA-MS, the effect that the degree of branching, as well as the free volume between macromolecular chains, has on the pyrolysis properties can provide information on the precursors at both the molecular and atomic levels. (iv) The preliminary investigation on preparing ceramic matrix composites. For tailoring the precursor structures and properties, the preparation of SiBCN ceramic matrix composites will be investigated. With regard to novel hyperbranched polymer ceramic precursors, the expected results of the investigation presented in this project should be useful not only for the development of high performance polymeric ceramic precursors, but also for applications of functional hyperbranched polymers.