Synthesis and properties of novel organosoluble aromatic poly(ether ketone)s containing pendant methyl groups and sulfone linkages

Several novel aromatic poly(ether ketone)s containing pendant methyl groups and sulfone linkages with inherent viscosities of 0.62–0.65 dL/g were prepared from 2‐methyldiphenylether and 3‐methyldiphenylether with 4,4′‐bis(4‐chloroformylphenoxy)diphenylsulfone and 4,4′‐bis (3‐chloroformylphenoxy)diphenylsulfone by electrophilic Friedel–Crafts acylation in the presence of N,N ‐dimethylformamide with anhydrous AlCl 3 as a catalyst in 1,2‐dichloroethane. These polymers, having weight‐average molecular weights in the range of 57,000–71,000, were all amorphous and showed high glass‐transition temperatures ranging from 160.5 to 167°C, excellent thermal stability at temperatures over 450°C in air or nitrogen, high char yields of 52–57% in nitrogen, and good solubility in CHCl 3 and polar solvents such as N,N ‐dimethylformamide, dimethyl sulfoxide, and N ‐methyl‐2‐pyrrolidone at room temperature. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 84.6–90.4 MPa, Young's moduli of 2.33–2.71 GPa, and elongations at break of 26.1–27.4%.