Chiral polyimide and its nanocomposites with graphene oxide using l-phenylalanine-based diamine

A new chiral diamine l-methyl 2-(3,5-diaminobenzamido)-3-phenylpropanoate (MABPP) was synthesized using l-phenylalanine (essential amino acid) as the starting material. The structure of the synthesized diamine was supported by FT-IR, ¹H, and ¹³C-NMR and mass spectral techniques. The diamine was polymerized with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) by thermal imidization method to produce a chiral polyimide (PI). Additionally, polyimide nanocomposites were also prepared by incorporating different ratios of graphene oxide (GO) in the PI matrix. The synthesized polyimide and PI/GO nanocomposites were characterized by FT-IR and Raman and NMR spectroscopy. The PI was found to have SOR of −71.4°. The inherent viscosity was found to be 0.87 dL g⁻¹ indicating that high molecular weight PI was formed. The surface morphology of the neat PI and PI/GO nanocomposites was studied by TEM and AFM, revealing uniform distribution of the nanoparticles in the PI matrix. The thermal properties were studied by DSC and TGA analysis. The dielectric constant was in the range of 2.8–5.0. Biological studies of both polyimide and PI/GO nancomposites elicit promising antimicrobial effects against Gram-positive and Gram-negative bacteria.