Posted: May 22nd, 2023
PEEK can be prepared through a condensation (step polymerization) reaction involving 4-4-difluorobenzophenone and an anion of hydroquinone (Nicholson 2006). A polar solvent with a high boiling point such as N-cyclohexyl-1-2-pyrrolidone is required to perform the reaction. Step polymerization occurs when functionally substituted monomers are condensed. Bifunctional reactants are used in synthesizing products with a high molar mass, whereas monofunctional substances regulate the reaction.
Trifunctional compounds contribute to the production of cross-linked or branched polymers. The mechanism involved in the synthesis of all PAEK is aromatic nucleophilic substitution in a reaction involving â€œactivated aryl dihalides with aromatic di-phenolates in a dipolar aprotic solventâ€ (Synthesis of aromatic polyketones via soluble precursors derived from bis (Î±-aminonitrile) s, n.d.). The Friedel-Crafts method or electrophilic acylation of aryl ethers can also be used.
The initial endeavour to synthesize PEEK utilizes DMSO and NaOH in a polycondensation reaction involving bisphenolate and activated halides. However, this method only produces PEEK with low molecular weight because high molecular weight PEEK is insoluble in DMSO. The use of diphenyl sulfonate as a solvent solves this hitch and enables the synthesis of PEEK with high molecular weight. The key setback of the synthetic route of synthesis is the high cost of fluoro monomers. The substitution of fluoro monomers with less expensive chloromonomers does not yield polymers with high molecular weight using dihalides triggered with carbonyl groups.
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