Design, synthesis, characterization, and applications of diol monomers, polyimides, and co-polyimides

Abstract

Two aromatic diimide-diol monomers N,N′-bis(4-hydroxynaphthyl)oxydiphthalic diimide and N,N′-bis(4-hydroxynaphthyl)biphenyl tetracarboxylic diimide were synthesized from aromatic dianhydrides and 5-amino1-naphthol. Polyimides (PIs) and co-polyimides (co-PIs) were synthesized from these new diols and 4,4′-dichlorodiphenyl sulfone through nucleophilic displacement reaction. The structures of the monomers and PIs and co-PIs were characterized by FT-IR and NMR analysis. The PIs and co-PIs were characterized by X-ray diffraction (XRD), thermogravimetry, differential scanning calorimetry, solution viscosity, solubility test, and dielectric properties test. XRD studies indicated that these PIs and co-PIs were amorphous in nature and were soluble in organic solvents. The PIs and co-PIs showed excellent thermal stability and the 10% weight loss occurred in the range 390–452 °C. The limiting oxygen index values of these PIs and co-PIs were in the range 37.9–42.3 and the value suggests that these PIs and co-PIs can be used as self-extinguishing polymers. These PIs and co-PIs found to have a dielectric constant in the range 3.88–4.56 and have excellent electrical insulation character and can be used as high temperature electrical insulation materials.