Controlling Iron Volatilization and Graphitization Through Pyrolysis in Benzoxazine Carbon Precursors

High Resolution Image Download MS PowerPoint Slide In this work, two benzoxazine networks, BisA–An and BisA–Fu, were synthesized with and without 15 wt % ferrocene to investigate the influence of polymer network structure on iron volatilization and subsequent graphitization behavior. It is hypothesized that increased network rigidity, associated with higher cross-link density, would suppress iron volatilization during pyrolysis to 1000 °C, thereby increasing the availability of catalytically active iron at graphitization temperatures (>700 °C). Iron evolution during pyrolysis was monitored using simultaneous thermal analysis–mass spectrometry (STA–MS), which revealed that the network with the least cross-linking functionality exhibited approximately an order of magnitude greater iron volatilization compared to networks with higher cross-linking functionality (from 1.27 × 10 –10 amps to 1.31 × 10 –11 amps). X-ray diffraction (XRD) analysis showed corresponding differences in graphitic crystallite development, with a calculated crystallite thickness (Lc) of 3.44 nm in the sample with less cross-linking functionality and 4.31 nm observed in samples with higher cross-linking functionality. These results demonstrate that polymer network structure governs iron retention during pyrolysis and, consequently, influences the extent of catalytic graphitization.