I.r. spectroscopy and 1H n.m.r. broad line studies of poly( p-phenylene sulphide) doped with sulphur trioxide

Abstract

I.r. spectra and temperature dependences of 1H n.m.r. linewidths were measured for poly( p-phenylene sulphide) (PPS) heavily doped with sulphur trioxide (SO 3) in the form of vapour and liquid. X-ray diffraction studies confirmed the total destruction of the crystalline phase as a result of the doping process. I.r. spectra show that doping with SO 3 leads to irreversible chemical modifications of the polymer by sulphonation. A comparison of the experimental values of the n.m.r. second moment determined for a rigid structure of the doped PPS with the poly(benzothiophene) excludes the formation of the latter as a result of doping. Doping with SO 3 in the vapour form leads to structural changes in the polymer with its two-phase character preserved. Annealing of the doped sample at 450 K results in the removal of chemically unbonded SO 3. However, the annealed polymer still has a different structure from the pristine polymer. PPS doped with liquid SO 3 shows a monophase structure indicated by a liquid-like resonance line.