|About this Abstract
||Materials Science & Technology 2019
||Ceramics and Glasses Simulations and Machine Learning
||Reactive MD Simulations of Polysiloxanes: Modeling the Polymer-to-Ceramic Route towards Silicon Oxycarbide Ceramics
||Ilia Ponomarev, Peter Kroll
|On-Site Speaker (Planned)
Polymer-derived ceramics such as silicon oxycarbide (SiCO) are synthesized via thermal treatment of polymeric precursors. Selection of starting materials and processing conditions is crucial for obtaining optimized materials. Here we present a new reactive force field (ReaxFF) that facilitates simulations of pyrolysis reactions with high fidelity. The force field has been developed in a learning process, and with excellent agreement to quantum-chemical simulations of small models, we perform simulations ranging several nano-seconds for models extending several nano-meters.
We apply the reactive force field to the synthesis of SiCO from polymethylhydridosiloxane (PMHS) cross-linked with divinylbenzene (DVB). Chemical species and total mass-loss observed during pyrolysis parallel experimental data. We obtain an amorphous composite of glass-like SiCO with embedded “free” carbon. The morphology and genesis of the free carbon phase changes characteristically during the pyrolysis. With the new force field, the possibility to study different precursors, cross-linkers, reactive atmospheres, and processing becomes feasible.