Designing thermoplastic oligomers with programmed degradation mechanisms using a combined empirical and simulation approach

Molecular simulation is used to probe the structure property relationships displayed by polysulphone (PS) and polyethersulphone (PES) and reproduces closely the temperatures at which thermal degradation occurs (and the glass transition temperatures). Both data sets agree well with those obtained empirically using TGA. The examination of the thermal and thermo-oxidative stability of thermoplastic oligomers (Mw = 5454-33,866 g mol−1, PDI 1.33-1.82) based on PS, PES, polyetherimide (PEI) and poly(amide-imide) (PAI), is reported. TGA reveals the least thermally stable polymer is PES (Td = ∼250 °C), while PAI (Td = ∼350 °C) is the highest: the materials usually display two-step decomposition patterns: scission of bridging group and degradation of backbone structure. A possible mechanism for the degradation of a PAI is proposed on the basis of the empirical and simulation data. This work provides a general method for the prediction of the thermal stability of oligomeric modifiers (and high molecular weight polymers).