Synthesis and comparative study on copolyetherimides from mixed isopropylidenebis(1,4-phenylene-oxy) bis(phthalic anhydride)s

Mixed isopropylidenebis(1,4-phenylene-oxy) bis(phthalic anhydride)s with different ratios ( Mixed-BPADA 1-3 ) were synthesized successfully via aromatic nucleophilic substitution from nitrophthalonitrile and bisphenol A. The corresponding copolyetherimides (CoPEIs) were prepared with two representative aromatic diamines (4,4′-oxydianiline (4,4′-ODA) and m -phenylenediamine ( m -PDA)) via two-step procedure and chemical imidization. CoPEIs showed T g s from 222 to 256 °C and T d5% s from 486 to 505 °C in argon, good mechanical properties (tensile moduli of 2.5–2.9 GPa, tensile strengths of 69–96 MPa, and elongations at break of 3.3–6.3%), and good solubility. With the introduction of 3-substituted phthalimide unit, CoPEIs displayed higher T g values, lower elongations, better solubility and larger d -spacings. The rheological properties of thermoplastic polyimide resins based on the Mixed-BPADA were investigated. CoPEI-b series displayed good melt processibility, and the CoPEI-3b derived from Mixed-BPADA 3 and m -PDA had the lowest melt viscosity among the copolymers . Compared to isomeric PEIs derived from BPADA isomers, CoPEIs displayed lower melt viscosities, indicating that the melt processibility had been greatly improved.