Synthesis and Characterization of New Highly Organosoluble Poly(ether imide)s Bearing a Noncoplanar 2,2‘-Dimethyl-4,4‘-biphenyl Unit and Kink Diphenylmethylene Linkage

Abstract

Two new bis(ether anhydride)s, 2,2‘-dimethyl-4,4‘-bis[4-(3,4-dicarboxyphenoxy)]biphenyl dianhydride (4A) and bis[4-(3,4-dicarboxy phenoxy)phenyl]diphenylmethane dianhydride (4B), were prepared in three steps starting from nitrodisplacement of 4-nitrophthalonitrile with 2,2‘-dimethylbiphenyl-4,4‘-diol and bis(4-hydroxyphenyl)diphenylmethane, respectively, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile)s and subsequent dehydration of the resulting bis(ether diacid)s. A series of new highly organosoluble poly(ether imide)s were prepared from the bis(ether anhydride)s and various diamines by conventional two-stage synthesis. The resulting poly(ether imide)s had inherent viscosities in the range of 0.55−0.81 dL·g-1. GPC measurement revealed that the polymers exhibited number-average molecular weight and weight-average molecular weight up to 45 000 and 82 000, respectively. All the polymers showed typical amorphous diffraction patterns. Almost all the poly(ether imide)s showed excellent solubility and readily dissolved in various solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide, pyridine, cyclohexanone, tetrahydrofuran, and chloroform. These polymers had glass transition temperatures in the range of 224−256 °C. Thermogravimetric analysis showed that all polymers were stable, with 10% weight loss recorded above 489 °C in nitrogen. The isothermal gravimetric analysis results demonstrated that these poly(ether imide)s showed weight losses of 7.0−10.5% after isothermal aging at 350 °C in static air for 20 h. These tough and flexible polymer films could be easily obtained by solution cast from the DMAc solution. These polymer films had tensile strength of 84−116 MPa and tensile modulus of 1.9−2.7 GPa.