Controlling Iron Volatilization and Graphitization Through Pyrolysis in Benzoxazine Carbon Precursors

Area of Science:

• Materials Science
• Polymer Chemistry
• Catalysis

Background:

• Benzoxazine resins are thermosetting polymers with tunable properties.
• Ferrocene incorporation can introduce catalytic activity for graphitization.
• Controlling iron loss during high-temperature processing is crucial for material performance.

Purpose of the Study:

• To investigate how polymer network structure affects iron volatilization during pyrolysis.
• To determine the influence of cross-link density on iron retention.
• To correlate iron retention with subsequent graphitic crystallite development.

Main Methods:

• Synthesis of two benzoxazine networks (BisA-An and BisA-Fu) with and without ferrocene.
• Pyrolysis up to 1000 °C.
• Simultaneous Thermal Analysis-Mass Spectrometry (STA-MS) to monitor iron evolution.
• X-ray Diffraction (XRD) to analyze graphitic crystallite structure.

Main Results:

• The network with lower cross-linking density showed significantly higher iron volatilization (approx. one order of magnitude greater) compared to highly cross-linked networks.
• Reduced iron volatilization in denser networks correlated with increased graphitic crystallite thickness (Lc).
• XRD analysis revealed Lc values of 3.44 nm for less cross-linked and 4.31 nm for more cross-linked samples.

Conclusions:

• Polymer network structure is a key factor in controlling iron retention during pyrolysis.
• Higher cross-link density effectively suppresses iron volatilization.
• Effective iron retention enhances catalytic graphitization, leading to improved graphitic structures.