Novel Melt-Processible Copolyetherimides Based on 4,4'-Diaminodiphenylmethane: Synthesis and Study

Abstract

The first synthesis of polyetherimides (PEIs) of a copolymer structure based on bisphenol-A 4,4'‑diphthalic anhydride and methylenedianiline, containing 10 to 100 mol % of rigid-chain fragments of benzophenone (BPDA) and pyromellitic (PMDA) dianhydrides, is described. The resulting polymers were analyzed using IR spectrometry, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and melt flow index measurements. Quantitative characteristics of the heat-resistance and processability indicators of synthesized PEIs depending on the content of rigid-chain fragments have been determined. Results show that increasing the content of BPDA and PMDA units in the PEI structure enhances the heat resistance and thermal stability of the polymers, although the melt flow index decreases. The explanation of the observed effect based on the growth of intermolecular interaction and the formation of a crystalline phase is given. Optimal ratios of precursor dianhydrides were identified to achieve the best balance of heat resistance and processability. The resulting PEIs of optimal structure have glass transition and thermal destruction temperatures up to 25–40°C higher in comparison with unmodified PEI whilst retaining the ability to be processed through the melt. The obtained results open up broad application prospects of the developed co-PEIs as highly heat-resistant engineering thermoplastic materials.