Carbonization and thermal expansion of glassy carbon derived from bis-ortho-diynylarenes

Bis-ortho-diynylarene (BODA) monomers form rigid polynaphthalene networks via thermal Bergman cyclizations at 300–400 °C. Upon further heating to 1000 °C, glassy carbon with high yield (>80%) is formed from the polynaphthalene precursor. Dilatometry was used to determine the linear coefficient of thermal expansion (CTE) of various BODA-derived glassy carbon. The measured CTE was similar to other glassy carbon-based systems ranging from 3.20 to 6.92 × 10−6 °C−1 over 20–1000 °C. An increase in short-range order was apparent when polynaphthalene networks were carbonized to 1500 °C; the CTE observed for such thermal cycling was 2.85–2.93 × 10−6 °C−1 over 20–1000 °C. Using dilatometry also provided insight on the carbonization mechanism to provide optimization of glassy carbon yields during thermal cycling.