Chemical reactions during thermal processing of hybrid organic-inorganic polymers transform the precursor into a ceramic. Here we present ab-initio molecular dynamic (aiMD) simulations of principal chemical reactions of this process. We detail simulations of polysiloxanes and polysilazanes with different carbon-bearing side groups yielding SiCO and SiCN ceramics. Models are evolved at elevated temperatures for simulation times between 0.1 and 1 ns.
We detail intra-chain and inter-chain coupling, cross-linking, and elimination reactions. Of particular interest are mechanisms that incorporate carbon into the -Si-O- and -Si-N- polymer backbone.
Beyond those principal chemical reactions, we can follow transformations of polydimethylsiloxane (PDMS) and polyvinylsilazane (PSZ20) into systems with mixed SiCnO4-n and SiCnN4-n tetrahedra. After removal of gaseous species, the systems evolve into SiCO and SiCN ceramics, respectively.