Molecular structure, kinetics and mechanism of thermal decomposition, molecular electrostatic potential, thermodynamic parameters and HOMO–LUMO analysis of coumarin-containing graft copolymer

This paper contains a combined theoretical and experimental study of thermodynamic, thermogravimetric and electronic properties of coumarin-containing graft copolymer. All the theoretical calculations were performed using the DFT (B3LYP) method with 6-311 + G (d, p) basis set in the ground state. From the optimized geometry of the coumarin-containing graft copolymer, atomic charge distributions, molecular electrostatic potential (MEP) surfaces, frontier molecular orbitals (FMOs) and thermodynamic properties such as entropy, enthalpy and specific heat capacity have been calculated theoretically. Finally, the activation energy and thermal degradation mechanism for graft copolymer were obtained by integral approximation methods under non-isothermal conditions. The activation energies (Ea) for thermal degradation of graft copolymer were determined by Flynn–Wall–Ozawa (FWO), Tang and Coats–Redfern (CR) methods. The study of kinetic equations showed that the reaction mechanism for graft copolymer was R3 mechanism, phase boundary-controlled reaction (contracting volume) of solid-state mechanism.