Synthesis and Properties of Novel Aromatic Polyamides with Xanthene Cardo Groups

Two novel monomers, 9,9-bis[4-(4-carboxyphenoxy)phenyl]xanthene (BCAPX) and 9,9-bis[4-(4-aminophenoxy)phenyl]xanthene (BAPX) were prepared in two main steps starting from nucleophilic substitution of 9,9-bis(4-hydroxyphenyl)xanthene (BHPX) with p-fluorobenzonitrile and p-chloronitrobenzene, respectively. Using triphenyl phosphite and pyridine as condensing agents, two series of polyamides containing xanthene cardo groups with the inherent viscosities (0.82-1.32 dL/g) were prepared by polycondensation from BCAPX with various aromatic diamines or from BAPX with various aromatic dicarboxylic acids in an N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride, respectively. All new polyamides were amorphous and readily soluble in various polar solvents such as N,N-dimethylformamide (DMF), NMP, N,N-dimethylacetamide (DMAc) and pyridine. These polymers showed relatively high glass transition temperatures between 264 and 308 C, decomposition temperatures at 10% weight loss ranging from 502 to 540 C and 488 to 515 C in nitrogen and air, respectively, and char yields at 800 C in nitrogen higher than 56%. Transparent, flexible, and tough films of these polymers cast from DMAc solutions exhibited tensile strengths ranging from 86 to 109 MPa, elongations at break from 13 to 22 %, and initial moduli from 2.15 to 2.63 GPa. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1650-1659, 2010