Synthesis and properties of polyimides derived from 3,3′,5,5′-tetramethyl-bis[4-(4-aminophenoxy)phenyl]sulfone

Abstract

The novel diamine containing methyl-substituted arylene sulfone ether, 3,3′5,5′-tetramethylbis[4-(4-aminophenoxy)phenyl]sulfone (TBAPS), was used as a monomer with various aromatic tetracarboxylic dianhydrides to synthesize polyimides via a conventional two-stage procedure that included ring-opening polyaddition in a polar solvent such as N,N-dimethylacetamide (DMAc) to give poly(amic acid)s, followed by cyclodehydration to polyimides. The diamine was prepared through the nucleophilic displacement of bis(4-hydroxy-3,5-dimethylphenyl)sulfone with p-chloronitrobenzene in the presence of K 2 CO 3, followed by catalytic reduction. Depending on the dianhydrides used, the poly(amic acid)s obtained had inherent viscosities of 0.80−1.72 dL g −1. All the poly(amic acid)s could be cast from DMAc solutions and thermally converted into transparent, flexible and tough polyimide films. The polyimide films had a high tensile strength range 81–118 MPa, an elongation range at break 5–9% and a tensile modulus range 1.78–2.49 GPa. The polyimide derived from 4,4′-hexafluoroisopropylidenebis-phathalic anhydride had better solubility than the other polyimides. These polyimides had glass transition temperatures between 291–339 °C and 10% mass loss temperatures were recorded in the range 550–591 °C in nitrogen and 556–588 °C in air atmosphere.