Exfoliation and dispersion of nano-sized modified-LDH particles in poly(amide-imide)s containing N-trimellitylimido-l-methionine and 3,5-diamino-N-(pyridin-3-yl)benzamide linkages
The present study describes the synthesis and characterization of nanocomposite materials built from the assembly of organic polymer and two-dimensional host materials of organo-modified layered double hydroxide (LDH). Organo-modified LDH was synthesized in one step from the co-precipitation reaction of the Al(NO3)3.9H2O, Mg(NO3)2.6H2O and bioactive N-trimellitylimido-l-methionine under ultrasonic irradiation. The X-ray diffraction (XRD) results of the organo-modified LDH show that the dianion is intercalated in the interlayer region of Mg–Al LDH and enlarges the interlayer distance. An optically active and organo-soluble poly(amide-imide) (PAI) was prepared by the direct step-growth polymerization reaction of l-methionine based diacid with 3,5-diamino-N-(pyridin-3-yl) benzamide in the presence of molten tetrabutylammonium bromide as a green solvent. Different nanocomposites of organo-modified LDH and chiral PAI were synthesized via solution intercalation method. The microstructures and thermal stabilities of the obtained LDH and nanocomposite materials were investigated by XRD, field emission scanning electron microscope (FE-SEM), Fourier transform infrared spectra, transmission electron microscopy (TEM) and thermogravimetry (TGA) techniques. The FE-SEM, TEM and XRD results revealed a coexistence of exfoliated and intercalated modified LDH in polymer matrix. TGA results showed improved thermal properties in comparison with the neat PAI.