Unraveling spatial variations of graphenization of Kapton polyimide via CO2 laser interaction: a comprehensive theoretical simulation and Raman spectroscopy mapping study

Laser-induced graphene is one of the advanced manufacturing techniques for transforming a non-biodegradable thermoset plastic (i.e., polyimide) to useful three-dimensional graphene. To analyze its effectiveness and improve usefulness of the novel technique it is essential to analyze the laser interaction and its variations that affects the associated properties. The present work focuses on developing carbon dots by Gaussian laser beam at varying irradiation time at constant spot diameter of ~ 567 µm to examine the modified structural relationships and their consequences on its functional properties. The development of highly localized and non-uniform energy distribution induces functional gradients across the laser spot as observed from the simulation and experimental results. The maximum observed temperatures from simulation results are 1913 °C, 2077 °C, and 2799.93 °C, respectively, at the center of the spot and the temperature varies spatially across the spot. Raman Mapping presents the modification in synthesized graphene spatially suggesting laser irradiation time having a significant effect in the functional properties. Spatial spot variation suggests that defect-to-graphitization ratio reduces for all laser irradiation from end of spot to the center. The properties of synthesized graphene also varied in average in-plane crystalline size increased from 34.5 ± 5 to 43.5 ± 17 nm in samples A and B, respectively. However, the crystallite size decreases to 37 ± 9 nm in sample C due to high temperature over the surface that leads to vaporization of carbon atom from the surface. These findings hold direct relevance for electro-chemical and flexible-electronics applications. Graphical abstract