Synthesis and characterization of new adamantane-type cardo polyamides

In this work, a new adamantane-type cardo dicarboxylic acid containing ether group, 2,2-bis[4-(carboxyphenoxy)phenyl]-adamantane (BCAPA), was prepared from 2,2-bis(4-hydroxyphenyl)adamantane and p-fluorobenzonitrile via the aromatic nucleophilic substitution reaction followed by hydrolysis. A series of new polyamides were prepared by the direct polycondensation of BCAPA and various diamines utilizing Yamazaki reaction conditions. The polymers were produced with moderate to high inherent viscosities of 0.65–1.06 dl g^–1. The polymers, except polymers PA4, PA7 and PA8, exhibited weight-average molecular weight and number-average molecular weight in the range of 57 400–106 000 and 32 500–58 200, respectively. Nearly all the polymers were readily soluble in polar solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, and N,N-dimethylformamide, as well as less polar solvents such as dimethyl sulfoxide, pyridine and γ-butyrolactone, and also in tetrahydrofuran. All of the polymers were amorphous and the polyamide films had a tensile strength and tensile modulus above 86 MPa and 2.0 GPa. These polyamides had glass transition temperatures between 254–292°C and 10% weight loss temperatures in the range of 450–507 and 481–516°C in nitrogen and air atmosphere, respectively.