Synthesis, Characterization, and Properties of Novel Aromatic UV Absorber Polyamides

Aromatic polyamides are well known as a main group of high performance and heat-resistant polymers. One of the drawbacks to utilize these polymers is the difficulty in processing due to their insoluble nature in aprotic organic solvents in addition to their high melting point or glass transition temperature. One way of overcoming the main problem of heat-resistant polymers - i.e., enhancing solubility without too much scarifying of the thermal stability is designing new monomers.

Firstly, bis(4-oxybenzoic acid)-1,5-anthraquinone (DA1) and bis(3-oxybenzoic acid)-1,5-anthraquinone (DA2) were prepared through aromatic nucleophilic substitution reaction of 4-hydroxybenzoic acid and 3-hydroxybenzoic acid with 1,5-dichloro anthraquinone, respectively. In the next step, the Yamazaki method was applied for synthesis of novel polyamides by polycondensation reaction of the obtained new diacids with commercial aromatic diamines such as oxydianiline (ODA), p-phenylene diamine (PPDA), 2,6-diaminopyridine (DAP), and diaminodiphenyl methane (DADPM) in presence of triphenylphosphite and pyridine as the activating agents and N-methyl-2-pyrolidone (NMP) as a solvent.

The structures of prepared novel monomers and polymers were characterized using different spectroscopy methods. The thermal and physical properties of novel polymers such as thermal stability and behavior, solubility, viscosity and ultra violet absorption were studied and the structure-property relationship of these polymers was investigated. The prepared polymers showed defined UV-Vis absorption bands at the range of 344-370 nm. Inclusion of an aromatic and bulky anthraquinone unit to the main chain of polymers led to high thermal stability while their solubility was improved in polar aprotic solvents.