Synthesis and properties of novel aromatic polyamides based on “multi-ring” flexible dicarboxylic acids

✍ Scribed by Sheng-Huei Hsiao; Hui-Yu Chang

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 698 KB
• Volume: 34
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199606)34:8<1421::aid-pola5>3.0.co;2-2

✦ Synopsis

The five benzene rings-containing (hereafter referred to as "five-ring") dicarboxylic acids a,a'-bis [4-(4-carboxyphenoxy)phenyl] -1,4-diisopropylbenzene (p-111) and a,a'-bis [ 4-(4carboxyphenoxy)phenyl] -1,3-diisopropylbenzene (n-111) were prepared by the fluoro-displacement of a,a'-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene and a,a'-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 03-111 and rn-111) and various aromatic diamines were directly synthesized in N-methyl-2-pyrrolidone (NMP) containing lithium chloride (LiC1) or calcium chloride (CaC1,) 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,Ndimethylacetamide (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°C. In nitrogen or air, all the polymers showed no significant weight loss up to 490°C, as indicated by thermogravimetric analysis (TG). 0