Synthesis and characterization of thermally stable camphor-based polyimide-clay nanocomposites

Abstract

A new monomer was prepared from (1R,3S)-(+)-camphoric acid. Novel polyimide and polyimide{clay hybrid composites were developed from one-pot condensation reactions of this monomer and pyromellitic dianhyride. Polyimidemontmorillonite nanocomposites were prepared from solution of polyimide and with di erent weight percentages (1, 5, 10 wt %) of organo-modi ed montmorillonite (OM-MMT) using N -methyl-2-pyrrolidone (NMP) as aprotic solvent. The reactive organoclay was formed by using hexadecylpyridinium chloride as a swelling agent for silicate layers of montmorillonite. The polyimide{clay composites lms (PI{MMT) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and X-ray di raction (XRD). All composites were subjected to di erential scanning calorimetry measurements for the purpose of examining Tg from all compositions. The clay content signi cantly in uenced the thermal behavior of the polymeric lms, such as glass transition and decomposition temperatures of polyimide{clay composites. The glass transition temperatures of the composites were higher than that of the original polyimide. Their thermal decomposition temperatures (Td = temperature at 5% mass loss) were measured via thermogravimetric analysis and showed that the introduction of clay into polymer backbones increased thermal stability. SEM, XRD, and the other conventional techniques were used for structural characterization. Dispersion of the modi ed clay in the polyimide matrix resulted in nanostructured material containing intercalated polymer between the silicate layers. The morphology and properties of PI nanocomposites greatly depend on the functional groups of the organic modi ers, synthesis procedure, and structure of polyimide because of the chemical reactions and physical interactions involved.