화학공학소재연구정보센터
Journal of Polymer Science Part A: Polymer Chemistry, Vol.34, No.8, 1421-1431, 1996
Synthesis and Properties of Novel Aromatic Polyamides Based on Multiring Flexible Dicarboxylic-Acids
The five benzene rings-containing (hereafter referred to as "five-ring") dicarboxylic acids alpha,alpha’-bis[4-(4-carboxyphenoxy)phenyl]-1,4-diisopropylbenzene (p-III) and alpha,alpha’-bis[4-(4-carboxyphenoxy)phenyl]-1,3-diisopropylbenzene (m-III) were prepared by the fluoro-displacement of alpha,alpha’-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene and alpha,alpha’-bis(4-hydroxyphenyl)-1,3-diisopropylbenzene with p-fluorobenzonitrile, and subsequent alkaline hydrolysis of the intermediate dinitriles. A number of high-molecular-weight polyamides based on these two "five-ring" dicarboxylic acids (p-III and m-III) and various aromatic diamines were directly synthesized in N-methyl-2-pyrrolidone (NMP) containing lithium chloride (LiCl) or calcium chloride (CaCl2) using triphenyl phosphite and pyridine as condensing agents. These polyamides were obtained with inherent viscosities above 0.51 and up to 0.91 dL/g. The weight-average molecular weight were in the range of 51,000-211,000. Most of these polyamides were amorphous and readily soluble in polar solvents such as NMP, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), and afforded tough, flexible, and transparent films by solution-casting. The films had tensile strength of 50-83 MPa, elongation to break of 4-8%, and tensile modulus of 1.3-2.0 GPa. Most polyamides showed distinct glass transitions on the differential scanning calorimetry (DSC) curves ranging from 147 to 177 degrees C. In nitrogen or air, all the polymers showed no significant weight loss up to 490 degrees C, as indicated by thermogravimetric analysis (TG).