Abstract
A new asymmetric biphenyl dianhydride, 2-o-tert-butylphenoxy-4,4′,5,5′-biphenyltetracarboxylic dianhydride, was readily synthesized via a four-step route. The key intermediate, 2-nitro-bis(N-methylphthalimide) (2), was synthesized at low temperature (around 15°C), with a yield of over 90%, which enhances the molecular adjustment flexibility of the monomer. FT-IR and 1H-NMR were used to fully verify the proposed structure of this new asymmetric dianhydride. The polyimides were prepared from such new dianhydride and commercial diamines by high-temperature one step polymerization in m-cresol. The molecular structures of the polymers were determined by FT-IR and 1H-NMR. The inherent viscosities were in the range of 0.40–0.41. The polymers show high organosolubility in common solvents such as NMP, CHCl3 and THF. TGA analysis revealed that the polymers displayed good thermal stability up to 490°C.