Thermal degradation kinetics and density functional study of a macromonomer containing dual-lactone

A macromonomer containing dual-lactone, MMDL, was characterized by thermal degradation kinetics and density functional theory (DFT) calculations. The frontier molecular orbitals, molecular structural geometry, molecular electrostatic potential (MEP) and electrostatic potential (ESP) maps were determined with the help of structure optimizations based on the DFT method with standard 3–21G* as a basis set that has polarization functions on the second row atoms only. The 3–21G* basis set comprises the same number of primitive Gaussian functions. The electronic properties, such as electron affinity, HOMO–LUMO energies, ionization energy, electronegativity, chemical potential, global hardness and softness, global electrophilicity were computed with the help of the DFT method. The MEP and ESP maps were determined to predict the reactive sites of the macromonomer. Finally, the activation energy and thermal degradation mechanism for the initial part of the decomposition process under non-isothermal conditions were determined from the thermogravimetric analysis by integral approximation methods. The decomposition activation energies of the macromonomer were computed with the help of Flynn–Wall–Ozawa, Coats–Redfern and Tang methods. The kinetic equations showed that the reaction mechanism was an R1 mechanism, which is a phase boundary-controlled reaction (one-dimensional movement) solid-state mechanism.