Abstract
The kinetics of the 'carbonate' route to poly(phenylene ether sulphone) (PES) was studied by three separate techniques. The first involved the use of Fourier Transform Infra-Red (FTIR) Spectroscopy, and studied the melt polymerisation between 4,4'-dichlorodiphenyl sulphone (DCDPS) and the bis potassium salt of 4,4'-dihydroxydiphenyl sulphone (Bis-S). The polymerisation was followed by either measuring the loss of the C-Cl group or the formation of the aryl ether group. Both methods led to the activation energy for the polymerisation being calculated to be ~ 109 kJmol[-1]. The viscosity of the solution polymerisation medium was also monitored to determine the activation energy of the reaction. This work showed that as the extent of reaction increased from p = 0.95 to p = 0.98 the polymerisation moved from being kinetically to diffusion controlled, as the activation energy reduced from ~ 93.5 kJmol[-1] to 21.8 kJmol[-1]. The main kinetic study involved the use of a model compound, namely the potassium salt of 4-(p-chlorobenzene sulphonyl)-4'-(p-hydroxy-benzenesulphonyl) diphenyl ether (chlorophenate dimer). Four concentrations of the model compound were studied in diphenyl sulphone (DPS), each yielding activation energies of ~109 kJmol-1. Rate constants were extrapolated to both zero and commercial manufacture concentrations. The mechanism of the 'carbonate' route to PES was also studied by three main techniques. The first involved the use of High Pressure Liquid Chromatography (HPLC) to study the growth and subsequent decline in the concentration of the chlorine-ended monomers and oligomers. This showed that there was little polymerisation below -265 C under normal operating conditions. The effective use of Field Desorption Mass Spectrometry (FDMS) to study the polymerisation was also demonstrated. The carbon dioxide (CO[2]) evolved during the polymerisation process was also monitored as a means of elucidating the mechanism. This showed three distinct phases of evolution. Although earlier work had suggested this to be due to partial potassium salt formation of Bis-S, it was found that DCDPS must also be involved as a consequence of the HPLC study. Two variants of PES were also studied for comparison. Finally, the polymerisation was studied both by solid state and liquid nuclear magnetic resonance (NMR). This indicated that 50% of the Bis-S reacted immediately, which seemed to contradict the CO2 evolution studies. A postulated reaction mechanism involving aryl carbonates is discussed.