Synthesis and Characterization of Some Polymers Using Benzimidazole Containing Diamine

Abstract

This thesis comprises the synthesis and characterization of benzimidazole containing polyimides and copolyimides. For this purpose, a previously reported benzimidazole containing monomer, 4-(2-(4-( 4-Aminophenoxy)phenyl)-1H-benzo[ d] imidazole-l -yl) aniline (DA), was synthesized and its polymerization was carried out with six different commercially available dianhydrides to make a series of polyimides and copolyimides. For the synthesis of co-polyimides, a commercial diamine 4,4'-oxydianiline (ODA) was used in combination with DA. Multiple characterization of the synthesized compounds were carried out. FTIR confirmed the absence of amine functional group and presence of imide functional group in polymers. XRD confirmed the amorphous nature of the polymers. The synthesized polyimides showed good thermal properties which was revealed by their glass transition temperature (T g) greater than 270°C, determined through DSC technique. Polyimides and copolyimides showed appreciable solubility inN-Methyl-2-pyrrolidine (NMP) andN,N'-Dimethylacetamide (DMAc) solvents. The photophysical properties of the polyimides and copolyimides were investigated by UV - visible and steady state photoluminescence spectroscopy which showed emission in visible region (violet region) and UV region for polyimides and copolyimides respectively. Cyclic voltarnmetry of the polyimides and copolyimides was done to analyze the onset oxidation potential values. Band gap value in the range of 3 to 3 .5e V and HOMO/LUMO values of the polymers were calculated which suggested that these polymers could be employed in optoelectronics.