Reduction of carbonyl groups in aromatic polyketones: synthesis and characterization of methylene-bridged polyaryl-ethers and -thioethers

The carbonyl groups in eight high-performance polyaryl-etherketones and -th ioetherketones were reduced to methylene linkages in high yield by treatmen t at room temperature with triethylsilane in a mixture of trifluoroacetic a cid or methanesulphonic acid with either dichloromethane or chloroform. Whe n the starting polyketone is readily-crystallizable, the reduced polymer al so tends to crystallize during workup. Amorphous polyketones likewise give amorphous reduction products. The methylene-bridged polymers in general hav e significantly lower melting points and/or glass transition temperatures t han their parent polyketones. (C) 1999 Elsevier Science Ltd. All rights res erved.