Tailored Synthesis of Nanostructured Polymer Thin Films from Optically Active and Thermally Stable Poly(amide-co-imide)s Containing Hydroxyl Pendant Groups in a Green Ionic Solvent

Abstract

Green and efficient synthesis of new chiral and thermally stable poly(amide-imide) (PAI) nanostructures was attained. Thus, polycondensation reaction of 3,5-diamino-N-(4-hydroxyphenyl)benzamide (4) with different chiral amino acid-based diacids (3a-3d) in the presence of small amount of molten tetrabutylammonium bromide as a molten ionic liquid and triphenyl phosphite were carried out. The obtained PAIs were characterized using FT-IR, specific rotation, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis, elemental analysis, and ¹H NMR technique. The FE-SEM micrographs showed that the synthesized PAIs are nanostructured polymers which nanosize particles are in the range of 46–66 nm after sonication process.

Keywords:

• Chiral polymer
• Green chemistry
• Ionic liquid
• Nanostructure
• Thin film

ACKNOWLEDGMENTS

The authors gratefully acknowledge the financial support of the Research Affairs Division Isfahan University of Technology (IUT). Further financial support from National Elite Foundation (NEF) and Center of Excellency in Sensors and Green Chemistry Research (IUT) is gratefully acknowledged.

Notes

^aPolymers were precipitated in methanol.

^bMeasured at a concentration of 0.5 g dL⁻¹in DMF at 25°C.

^cMeasured without filter.

^a The polymer sample was dried in vacuum at 80°C for 8 h.

^a From UV-Vis absorption spectra measured in NMP solution (0.02 mg/mL) at room temperature. Values in parentheses are those measured in polymer films.

^b PL spectra measured in NMP solution (5 mg/mL) at room temperature. No discernible PL peak was observed.

^c The cutoff wavelengths (λ ₀ ) from the transmission UV-vis absorption spectra of polymer films.

^a Temperature at which 5 and 10% weight loss was recorded by TGA at a heating rate of 20°C/min in a nitrogen atmosphere.

^b Percentage weight of material left undecomposed after TGA analysis at maximum temperature 800°C in a nitrogen atmosphere.

^c Limiting oxygen index (LOI) evaluating at char yield at 800°C.

^a Y _S : Yield strength, T _S : Tensile strength, E _B : Elongation at break, Y _M : Young's modulus.