Opportunities and Challenges in the Use of TiO₂ Nanoparticles Modified with Citric Acid to Synthesize Advanced Nanocomposites Based on Poly(amide-imide) Containing N,N′-(Pyromellitoyl)-bis-L-leucine Segments

Abstract

In this study, the goal was the preparation, characterization, and surface morphology of poly(amide-imide)/TiO₂-citric acid nanocomposites (PAI/TiO₂-CA NCs). Owing to the high surface energy and tendency for agglomeration, the surface of TiO₂ nanoparticles was modified with citric acid. Then poly(amide-imide) was synthesized by direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-L-leucine diacid with 4,4′-diaminodiphenylmethane by triphenyl phosphite and tetra-n-butylammonium bromide as a green medium. The attained polymer and modified TiO₂ nanoparticles were used to prepare PAI/TiO₂-CA NCs through ultrasonic irradiation. The resulting PAI/TiO₂-CA NC was characterized with FT-IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis.

Keywords:

• Chiral poly(amide-imide)
• Green solvent
• Modified TiO₂ nanoparticle
• Nanocomposites
• Ultrasonic irradiation

Notes

^a Temperature at which 5% weight loss was recorded by TGA at heating rate of 20°C/min under an argon atmosphere.

^b Temperature at which 10% weight loss was recorded by TGA at heating rate of 20°C/min under an argon atmosphere.

^c Weight percentage of material left undecomposed after TGA analysis at a temperature of 800°C under an argon atmosphere.

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

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