Improved syntheses of poly(oxy-1,3-phenylenecarbonyl-1,4-phenylene) and related poly(ether–ketones) using polyphosphoric acid/P2O5 as polymerization medium

• Published in: Polymer (Guilford) Vol. 44; no. 15; pp. 4135 - 4147
• Main Authors: Baek, Jong-Beom, Tan, Loon-Seng
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01.07.2003
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Phosphorus oxide; Phenylene oxide copolymer; Solution polycondensation; Self condensation; Ether copolymer; Experimental study; Optimization; Thermal stability; Operating conditions; Ketone copolymer; Benzoic acid derivatives; Poly(phosphoric acid); Electrophilic substitution; Polyphosphoric acid; Preparation; Aromatic copolymer; Alternating copolymer; Thermostable; AB monomer; Poly(ether-ketones)
• ISSN: 0032-3861
• DOI: 10.1016/S0032-3861(03)00374-4

Based on the model-compound studies, the composition of polyphosphoric acid (PPA)/P2O5 mixture as an effective catalytic/dehydrative medium for the preparation of poly(ether-ketones) was optimized. Thus, with the optimal weight ratio of 4:1 (PPA:P2O5), the electrophilic substitution polycondensation of 3-phenoxybenzoic acid and related AB monomers was substantially promoted at 130 DGC to yield the subject polymer abbreviated as mPEK and related poly(ether-ketones) with significantly higher molecular weights. In the cases where the polymerization systems were completely homogeneous, the ensuing polycondensation was rapid and yielded high molecular weight polymers (e.g. mPEK [*h]=2.10dl/g) at 130 DGC within 30 min., as compared to PPMA (phosphorus pentoxide /methanesulfonic acid) method which gave only moderate molecular weight polymers, e.g. mPEK ([*h]=0.64dl/g). In some cases, where the monomers and PPA/P2O5 were not fully compatible, polycondensation did proceed and reasonable molecular weight range ([*h]=0.69-0.76dl/g) could be achieved. However, the complete incompatibility between the poly(ether-sulfone) and PPA/P2O5 medium precluded the successful polymerization of 4-phenoxybenzenesulfonic acid.