Synthesis and characterization of fluorinated poly(amide imide)s derived from 1,4-bis(2?-trifluoromethyl-4?-trimellitimidophenoxy)benzene and aromatic diamines

Poly(amide-imide)s obtained from 3,5-diamino-N-(thiazol-2-yl)-benzamide and dicarboxylic acids containing various amino acid units

This study reports a green approach toward the synthesis of novel optically active poly(amide-imide)s (PAI)s bearing thiazole moiety, which was formed by the polycondensation reaction of 3,5-diamino- N-(thiazol-2-yl)benzamide and various diacids containing natural amino acids in molten tetrabutylammonium bromide. Diamine monomer was synthesized by the reduction of 3,5-dinitro- N-(thiazol-2-yl)benzamide in methanol using iron oxide hydroxide as a catalyst. This catalyst can rapidly reduce the sulfur and azo-containing aromatic nitro compounds to the corresponding amines in high yield by employing hydrazine hydrate as a hydrogen donor. Chiral diacid monomers were synthesized in high yield through the reaction of pyromellitic dianhydride and amino acids (l-isoluecine, S-valine, S-methionine, and l-phenylalanine) in acetic acid. The direct polymerization reactions of these monomers provided a series of new optically active PAIs with inherent viscosities in the range of 0.20–0.28 dL g−1. The obtained polymers were characterized by Fourier-transformed infrared spectroscopy, specific rotation measurements, and the representative of them by proton nuclear magnetic resonance and elemental analysis techniques.

Synthesis and Characterization of Thioether and Pyridine-Bridged Aromatic Polyimides with High Refractive Indices and High Glass Transition Temperatures

In this study, a novel aromatic diamine containing thioether and pyridine linkages, 2,6-bis[4-(4-aminophenylenesulfanyl)phenyl]-2-phenylpyridine (BASPP), was synthesized and characterized. The BASPP, along with several other sulfur-containing diamines, including 4,4′-( p-phenylenedisulfanyl) dianiline (2SPDA), 4,4′-bis( p-aminophenylsulfanyl)biphenyl (2SBPA), 4,4′-sulfonylbis[( p-phenylenesulfanyl)aniline] (BADPS), and 2,7-bis( p-aminophenylenesulfanyl)thianthrene (APTT) were polymerized with a sulfur-containing dianhydride, 4,4′-thiodiphthalic anhydride (TDPA), via a two-step polycondensation procedure to obtain five polyimides (PI-1 to PI-5). Flexible, tough, and transparent polyimide (PI) films with tensile strengths that ranged from 78.6 to 96.3 MPa were successfully cast from their poly(amic acid) (PAA) precursors. The PI films exhibited good thermal stability with glass transition temperatures ( T g values) as high as 265°C and 5% weight loss temperatures > 505 °C. The high sulfur contents and flexible thioether linkages endowed the PI films with refractive indices ( nav) as high as 1.7166 at 1310 nm and birefringence ( Δn) < 0.01. The PI-4, containing both pyridine and thioether moieties in the main chain, exhibited the best combined properties, including Tg of 265 °C, nav of 1.6966, Δn of 0.0078, and optical transmittance of 88% at 450 nm at the film thickness of 10 µ m.