Understanding polymer pyrolysis-induced defect healing and doping in graphene

A new method of post-synthesis doping/healing through the rapid thermal degradation of the polymer coating on defective graphene named “nanobandage” is a promising approach to reducing the number of defects introduced in graphene during manufacturing processes, improving its electronic and mechanical properties. However, the thermal fragmentation process of the polymers and their interactions with the defects are still unknown, and this knowledge would be useful to optimize and apply it to 2D materials other than graphene. In this study, reactive molecular dynamics simulations were used to investigate this process using polyethylenimine (PEI) films deposited on graphene oxide. The results are validated with experimental results obtained by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS),  and revealed that degradation begins in the large branches of the PEI structure, and small fragments of less than 100 Da are responsible for highly effective defect healing and nitrogen doping. This understanding of polymer degradation and doping in the model system can help optimize the method and explore its application in other 2D materials with different doping agents.