ReaxFF Molecular Dynamics Simulations of the Thermally Induced Decomposition of Poly(9-(1-octanoyl)-9H-carbazole-2,7-diyl) on Single-Walled Carbon Nanotube Films: Implications for Nanoelectronics

Poly[9-(1-octanoyl)-9H-carbazole-2,7-diyl] (PCz) is widely employed as a dispersant for fabricating high-quality semiconducting single-walled carbon nanotube (SWCNT) films, yet its removal from SWCNT surfaces remains challenging for device performance optimization. While thermal decomposition has been adopted industrially, the atomic-scale removal mechanism remains poorly understood. Here, we employed reactive force field molecular dynamics (ReaxFF MD) simulations to systematically investigate the thermally induced decomposition of PCz on SWCNT film surfaces. Three representative models were constructed: randomly wrapped PCz-SWCNT, surface-adsorbed PCz-SWCNT, and pure PCz multichain systems. Our results reveal that PCz decomposition initiates with preferential cleavage of side-chain C–N bonds at approximately 1500 K, followed by main-chain degradation above 2250 K. Interfacial configurations significantly influence decomposition pathways: the wrapped model exhibits enhanced thermal stability through strong π–π interactions, while the surface-adsorbed model demonstrates earlier chain detachment and more complete fragmentation due to weaker interfacial binding. Product distribution analysis reveals a characteristic three-stage decomposition pathway: initiating with side-chain detachment via C–N bond cleavage, progressing through intermediate formation and consumption during main-chain degradation, and culminating in radical-mediated formation of C₁–C₅ light hydrocarbons alongside char precursors at extreme temperatures. These atomic-scale insights provide fundamental understanding for optimizing thermal removal processes in SWCNT-based nanoelectronics fabrication.