Poly(amide-imide)/modified-TiO2 nanocomposites containing laterally-attached benzimidazole moieties: preparation, morphological, and thermal characterization

Abstract

ABSTRACT This study describes the fabrication, characterization, and properties of poly(amide-imide)/ modified-TiO2 nanocomposites (PAI/m‐TiO2 NCs) containing benzimidazole pendant groups. To this point, a soluble aromatic PAI bearing two pendant benzimidazole rings per repeat unit was first synthesized from the polymerization reaction of 2-[3,5-bis(N-trimellitimidoyl)phenyl]benzimidazole (2) with 5‐(2‐benzimidazole)‐1,3‐phenylenediamine (1) with high yield as a polymer matrix. To avoid agglomeration and improve dispersion of TiO2 nanoparticles (NPs) in the PAI matrix, the periphery of TiO2 NPs was coated by 3‐aminopropyltriethoxysilane (APS) to form m-TiO2 NPs. Thermogravimetric analysis (TGA) and Fourier-transform infrared (FTIR) spectroscopy confirmed the presence of the modifier on the surface of NPs. Subsequently, in order to prepare the PAI/m-TiO2 nanocomposites, various contents (5, 10, and 15 wt%) of the functionalized TiO2 were embedded into the PAI matrix. The structure, morphology, and thermal properties of the obtained hybrids were characterized by FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and TGA. Morphological studies indicated that the m-TiO2 NPs were dispersed in the PAI matrix without any aggregation. The TGA of nanocomposites confirms the improvement in the thermal stability with an increase in the percentage of m-TiO2 NPs.