Ab initio study on thermal degradation reactions of polycarbonate

An ab initio study on thermal degradation of polycarbonate, poly(bisphenol A carbonate), PC, was carried out using Hartree-Fock (HF) and density functional (B3LYP) methods. The polycarbonate chain was modelled by a dimer unit (PC-2), which represented a fragment of the polymer chain. The main emphasis was on the determination of reaction enthalpies and Gibbs energies for the different degradation reactions, which were calculated at a standard state (298.15 K) and at a higher temperature (673.15 K). On the basis of the calculated Gibbs energies, the various degradation paths were ranked according to their favourableness and spontaneity and found to agree well with experimental data. The CO2 elimination reaction and substitution reaction with water were found to be the most favourable reaction paths. (C) 2003 Elsevier B.V. All rights reserved.