About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
Molecular Approaches to Ceramics; Synthesis, Processing, Modeling, and Derived Ceramics
|
| Presentation Title |
Visualizing Polymer to Ceramic Transformations in SiOC Polymer Derived Ceramics with In Situ Transmission Electron Microscopy |
| Author(s) |
Prathiba Thamishavel, MD Islam Shafiqul, Taylor J. Woehl |
| On-Site Speaker (Planned) |
Taylor J. Woehl |
| Abstract Scope |
Polymer derived ceramics (PDCs) possess unique processability, low processing temperatures, and have the potential for molecular scale control over ceramic properties; however, their formation pathway remains poorly understood. Here we use in situ high temperature transmission electron microscopy (TEM) to visualize transformation of polysiloxanes to SiOC ceramics with nanometer spatial resolution. Polysiloxane microparticles were heated in the TEM at 10 °C/min to 1200 °C. Polysiloxane particles underwent volumetric shrinkage starting at 500 – 600 °C. Some particles formed pores while others did not, suggesting heterogeneity in the curing state of the preceramic polymers. Particles that formed pores were nearly entirely carbonized by the end of pyrolysis, suggesting these particles had low crosslinking density. No cracking and little shape change was observed during heating, likely due to the short gas diffusion pathway in the microparticles. Heating to 1200 °C produced ceramic particles with increased Si:C ratio, consistent with hydrocarbon vaporization and ceramization. |