Sulphonated poly(ether ether ketone): Synthesis and characterisation.

The sulphonation of commercially available PEEK in powder form (Gatone™, Gharda Chemicals Limited, India) was carried out using conc. H2SO4 under different reaction conditions. The duration of reaction was varied from 3-5 h, polymer concentration 4-10% (w/v) and temperature 35-50°C. Structural characterisation of sulphonated polymers was done by elemental analysis, FT-IR and1H-NMR spectroscopy. The degree of sulphonation as calculated from1H-NMR and elemental analysis (S-content) was found to be in the range of ~ 50-80%. Multistep mass loss was observed in thermogravimetric traces (recorded in N2 atmosphere). The first step (50-225 ± 25°C) was due to loss of moisture (1-10%) and second step (250-425 ± 25°C) has been attributed to volatilization of SO3 from the sulphonic group. The backbone degradation takes place above 450°C. The mechanical properties and proton conductivities of various sulphonated samples was also evaluated. [ABSTRACT FROM AUTHOR]