Synthesis and properties of polyaryletherketones

Crystalline polyarletherketones of high molecular weight have been prepared previously by polycondensation of aroyl fluorides such as 4-phenoxybenzoyl fluoride in liquid HF, but not by polyether synthesis because these polymers are not soluble in the recommended (see Farnham et al., J. Polym. Sci., Al, 1967, 5, 2375) dipolar aprotic solvents such as dimethyl sulphoxide or sulpholane. We find that tough, crystalline polyaryletherketones and copolyaryletherketone-sulphones can be obtained by polycondensation of bis-4-halogenophenyl ketones (plus bis-4-halogenophenyl sulphones for copolymers) with the potassium salts of bis-4-hydroxyphenyl ketones at 280°–340°C using certain diaryl sulphones as solvents for the reactions. There is no evidence for structural anomalies in the polyetherketone made by polycondensation of bis-4-fluorophenyl ketone with the bis-phenoxide from bis-4-hydroxyphenyl ketone, but synthesis of this polymer by polycondensation of the potassium salt of 4-fluorophenyl 4-hydroxyphenyl ketone gave products containing some gel and soluble polymer in which the chains appear to be branched. Several different polyaryletherketones give almost identical X-ray diffraction patterns, and in the unit cells of these polymers (fibre repeat distance 10.0Å) ether and carbonyl linkages are interchangeable; Tg and Tm for these polymers are recorded.