Synthesis and Characterization of New, Soluble and Low-κpoly(aryl ether ketone)s containing Tetramethyl and Xanthene groups in Structural Units

9,9-Bis (3,5-dimethy1-4-hydroxyphenyl)xanthene (BDMHPX) was prepared in good yield by a HCl/ZnCl2-catalyzed condensation reaction ofxanthenone with 2,6-dimethylphenol. Then, several new cardo aromatic poly(ether ketone)s (PEKs) containing tetramethyl and xanthene groups in structural units were synthesized by nucleophilic substitution polycondensation reaction of BDMHPX with various difluorinated aromatic ketones in N,N-dimethylacetamide (DMAc) in the presence of anhydrous potassium carbonate. High molecular weight PEKs having number average molecular weights (M-n ' s) in the range of 22,000-27,000 g/mol with the polydispersity index ranged from 1.8 to 2.0 were all amorphous, and showed high glass transition temperatures ranging from 231 to 277 degrees C, good thermal stability, and the 5 % weight loss temperatures were over 418 degrees C with char yields above 55 % at 650 degrees C in nitrogen. These new PEKs were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone and DMAc, as well as chloroform and tetrahydrofuran, and could form transparent, strong, and flexible films with tensile strengths of 57-67 MPa, Young's moduli of 2.02-2.27 GPa, and elongations at break of 7-12 %. They also showed lower dielectric constants (k = 2.68-2.80 at 1 MHz) and low water absorptions (0.46-0.60 %).