Uncovering atomic-scale polymer-to-ceramic transformations in SiC polymer derived ceramics from polycarbosilanes

Polycarbosilanes (PCS) are organosilicon polymers that can be converted into silicon carbide (SiC) ceramics upon pyrolysis. The phase compositions and microstructure of the final ceramic are notably impacted by the interplay of both polymer morphology and chemical functionality. Such characteristics hold tremendous potential for developing polymer derived ceramics (PDCs) with optimized properties if the complexities inherent to such materials are better understood at the atomic-scale. This study investigates the structural changes associated with the polymer-to-ceramic conversion in SiC systems derived from the pyrolysis of commercial PCS: SMP-10, SMP877 and SMP-730, across a temperature range of 250-1600 degrees C. Using a combination of synchrotron X-ray spectroscopy and scattering methods, we reveal heterogeneous structures with varied compositions, influenced by both pyrolysis conditions and initial PCS functionalities. This study offers a promising approach for understanding the devitrification and compositional heterogeneity (C vs. SiC phases) in polymer-to-ceramic conversion.