Synthesis and characterization of new soluble polyamides from 1,1-bis[4-(4-carboxyphenoxy)phenyl]-4-tert-butylcyclohexane and various diamines

A new dicarboxylic acid monomer, 1,1-bis[4-(4-carboxyphenoxy)phenyl]-4-tert-butylcyclohexane, bearing a pendent tert-butylcyclohexylidene group was prepared in three steps from 4-tert-butylcyclohexanone. The monomer was reacted with various diamines to produce a series of new polyamides with triphenyl phosphite and pyridine as condensing agents. These polyamides were produced with inherent viscosities of 0.74 to 1.02 dL g−1. All the polymers were characterized by X-ray diffraction that revealed this amorphous nature. These polymers exhibited excellent solubility in a variety of solvents. Almost all the polymers could be dissolved in N-methyl-2-pyrrolidinone, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, dimethyl sulfoxide, pyridine, and even in tetrahydrofuran and cyclohexanone. These polymers showed glass-transition temperatures between 223 and 256 °C and decomposition temperatures at 10% weight loss ranging from 468 to 491 °C and 469 to 498 °C in nitrogen and air atmospheres, respectively. Transparent, tough, and flexible films of these polymers were cast from the DMAc solutions. These polymer films had tensile strengths ranging from 76 to 99 MPa, elongations at break from 7 to 19%, and initial moduli from 2.1 to 2.7 GPa.