Synthesis and properties of aromatic polyamides based on 4,4′-(1,5-naphthalenedioxy)dibenzoic acid

✍ Scribed by Sheng-Huei Hsiao; Kuan-Yu Chu

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 580 KB
• Volume: 198
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1997.021980313

✦ Synopsis

Abstract

4,4′‐(1,5‐Naphthalenedioxy)dibenzoic acid (3), a novel aromatic dicarboxylic acid monomer, was prepared by nucleophilic substitution reaction of 1,5‐dihydroxynaphthalene and p‐fluorobenzonitrile in N,N‐dimethylformamide (DMF) in the presence of potassium carbonate and subsequent alkaline hydrolysis of the intermediate dinitrile, 4,4′‐(1,5‐naphthalenendioxy)dibenzonitrile. Using triphenyl phosphite (TPP) and pyridine as condensing agents, a series of novel aromatic polyamides were synthesized by direct poly‐condensation of diacid 3 and twelve aromatic diamines in N‐methyl‐2‐pyrrolidone (NMP) solution containing dissolved calcium chloride. The resulting polyamides had inherent viscosities above 1,14 and up to 4,45 dL/g. Most of these polyamides are readily soluble in polar solvents, such as NMP, DMF, and N,N‐dimethylacetamide (DMAc). Transparent, flexible, and tough films could be cast from their DMAc or NMP solutions. Most of these polymers were amorphous in nature, as indicated by their wide‐angle X‐ray diffractograms. Thermogravimetric analysis (TG) showed that all the polyamides were stable up to 450°C in both air and nitrogen atmosphere. Most of them revealed a distinct glass transition on the differential scanning calorimetry (DSC) traces in the range of 183–259°C.