Synthesis and characterization of polyimides based on isopropylidene-containing bis(ether anhydride)s

Abstract

Two bis(ether anhydride)s, 4,4′-[1,4-phenylenebis(isopropylidene-1,4-phenyleneoxy)]-diphthalic anhydride (IVa) and 4,4′-[isopropylidenebis(1,4-phenylene)dioxy]diphthalic anhydride (IVb), were prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 4-nitrophthalonitrile with α,α ′-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene (Ia) and 4,4′-isopropylidenediphenol (Ib) in N,N-dimethylformamide (DMF) in the presence of potassium carbonate. The bis(ether anhydride)s IVa and IVb were polymerized with various aromatic diamines to obtain two series of poly(ether amic acid)s VIa–g and VIIa–g with inherent viscosities in the range of 0.30∼0.74 and 0.29∼1.01 dL/g, respectively. The poly(ether amic acid)s were converted to poly(ether imide)s VIIIa–g and IXa–g by thermal cyclodehydration. Most of the poly(ether imide)s could afford flexible and tough films, and they showed high solubility in polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, and m-cresol. The obtained poly(ether imide) films had tensile strengths of 45∼83 MPa, elongations-to-break of 6∼27%, and initial modulus of 0.6∼1.7 GPa. The Tgs of poly(ether imide)s VIIIa–g and IXa–g were in the range of 194∼210 and 204∼243 °C, respectively. Thermogravimetric analysis (TG) showed that 10% weight loss temperatures of all the polymers were above 500 °C in both air and nitrogen atomspheres.