High refractive index and low-birefringence polyamides containing thiazole and naphthalene units

• Main Authors: Javadi, Ali, Najjar, Zahra, Bahadori, Saedeh, Vatanpour, Vahid, Malek, Ali, Abouzari-Lotf, Ebrahim, Shockravi, Abbas
• Format: Article
• Published: Royal Society of Chemistry 2015
• Subjects: T Technology (General); TP Chemical technology
• Online Access: http://eprints.utm.my/id/eprint/55575/; http://dx.doi.org/10.1039/c5ra18898a

Highly refractive and solution processable polyamides (PAs) were synthesized by the introduction of thiazole rings, naphthalene groups, and thioether linkages. These PAs were synthesized by the polycondensation of a new diamine monomer, 5,5'-thiobis(2-amino-4-(2-naphthyl)thiazole) (DA), with various aromatic diacids. The bulky pendant naphthyl units endowed the resulting PAs with non-coplanar structures and excellent solubilities in organic solvents. The obtained PAs showed high thermal stability, with 10% weight loss temperatures exceeding 478°C under nitrogen and 431°C in air atmosphere, while their glass transition temperatures were in the range of 194-229°C. The synergic effects of the thiazole groups, naphthyl substituents, and thioether linkages provided PAs with very high refractive indices of up to 1.7701 at 632.8 nm, along with small birefringences (<0.0076) and high Abbe's numbers. The structure-property relationships of these PAs due to the presence of naphthyl substituents were also studied in detail by comparing the results with the previously reported analogous PAs