| About this Abstract |
| Meeting |
Materials Science & Technology 2020
|
| Symposium
|
Ceramics and Glasses Simulations and Machine Learning
|
| Presentation Title |
Ab-initio and Reactive MD Simulations of Polymer Pyrolysis and Formation of Silicon-based Ceramics
|
| Author(s) |
Peter Kroll |
| On-Site Speaker (Planned) |
Peter Kroll |
| Abstract Scope |
We perform ab-initio molecular dynamic (aiMD) simulations of polymer pyrolysis of different polysiloxanes and polysilazanes. Models comprise 400 to 1000 atoms and exhibit different polymer side groups. Simulations are performed for 20 to 100 ps at high temperatures. We detect developing gaseous species and follow trajectories of fundamental processes in detail. We observe the Kumada-type rearrangement, hence, insertion of carbon from aliphatic side groups into the polymer back-bone. This process changes the local environment of Si and facilitates formation of mixed SiCnO4-n-tetrahedra.
Time and length scales of the aiMD simulations are augmented by orders of magnitude using a complex reactive force field (ReaxFF) that we continuously develop. We show that formation of carbon segregations in amorphous SiCO is linked to early stages of polymer degradation, when organic and inorganic portions of the polymers partition and segregate. Further reactions within the organic portion then yields sheet-like or tubular carbonaceous segregations. |