Synthesis and Characterization of Highly Organosoluble Polyimides Based on a New Asymmetric Dianhydride

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.

Keywords:

• POLYIMIDE
• ASYMMETRIC DIANHYDRIDE
• SOLUBILITY
• THERMAL STABILITY