Polyimides based on unsymmetrical 3,4′-[4,4′-(diphenyldioxy)]diphthalic anhydride: synthesis and properties

Abstract

A series of new polyetherimides (PEIs) based on unsymmetrical 3,4′-(4,4′-(diphenyldioxy)diphthalic anhydride and a number of diamines were synthesized by single-stage high-temperature catalytic polycondensation in molten benzoic acid used as the so-called “active medium”. The chemical structure and phase morphology of the polycondensation products were studied by ¹H NMR and IR spectroscopies and by wide-angle X-ray scattering. The molecular weight characteristics were studied by viscometry and GPC methods. The synthesized PEIs are high-molecular-weight, film-forming, amorphous polymers that are soluble in organic solvents and possess good mechanical properties. The thermal properties of the synthesized PEIs were evaluated by DSC, TMA, and TGA methods. The polymers have high thermal and thermo-oxidative stability (> 500 °C), while their glass transition temperatures lie in the range of 220–300 °C depending on the diamine used in the synthesis. The rheological properties of melts were studied for a number of thermoplastic PEIs.