About this Abstract |
Meeting |
MS&T21: Materials Science & Technology
|
Symposium
|
Preceramic Polymers; Synthesis, Processing, Modeling, and Derived Ceramics
|
Presentation Title |
Atomistic Simulations of Polymer Pyrolysis |
Author(s) |
Peter Kroll |
On-Site Speaker (Planned) |
Peter Kroll |
Abstract Scope |
Polymer-derived ceramics are processed via the thermal treatment of polymer precursors. Chemical reactions during thermal processing convert the hybrid organic-inorganic polymer into an amorphous ceramic. A persistent challenge is to address how precursor architecture and processing conditions affect a final material. Computational studies of the principal chemical reactions during processing are scarce, not at least due to the complexity of the problem arising on different time and length scales.Here we present atomistic simulations of the polymer pyrolysis of polysiloxanes and polysilazanes. We use both ab-initio as well as empirical reactive force field (ReaxFF) Molecular Dynamic Simulations. We observe detailed mechanisms of cross-linking and elimination reactions, yielding intra- and inter-chain coupling. Kumada-like rearrangements incorporate carbon into the -Si-O- and -Si-N- polymer backbone. Segregation of excess carbon occurs into poly-aromatic hydrocarbons. Continuing annealing goes along with significant mass loss, and systems evolve into SiCO and SiCN ceramics, respectively. |