Preparation and properties of polymides, polyamides and poly(amide‐imide)s based on a spirobichroman dietheramine

A novel diamine, 7,7′‐bis(4‐aminophenoxy)‐4,4,4′,4′‐tetramethyl‐2,2′‐spirobichroman ( 3 ), was synthesized and used as a monomer with various aromatic tetracarboxylic dianhydrides, dicarboxylic acids and imide ring‐containing dicarboxylic acids, to synthesize polymides, polyamides and poly(amide‐imide)s, respectively. The polyimides 5a–f were prepared from diamine 3 and various aromatic tetracarboxylic dianhydrides via a conventional two‐stage procedure. The intermediate poly(amic acid)s had inherent viscosities of 0,84 – 1,65 dL/g and could be thermally converted into transparent, flexible, and tough polyimide films. Some polyimides were readily soluble in polar solvents such as N , N ‐dimethylacetamide (DMAc) and N ‐methyl‐2‐pyrrolidone (NMP). The glass transition temperatures ( T g ) of these polyimides were in the range of 155–280°C, and 10% weight loss temperatures were above 450°C in air or nitrogen. Furthermore, a series of polyamides and poly(amide‐imide)s having inherent viscosity between 0,40–1,69 dL/g were prepared by direct polycondensation of the diamine 3 with various aromatic dicarboxylic acids and imide ring‐containing dicarboxylic acids. All the polyamides and poly(amide‐imide)s were soluble in a variety of organic solvents and could be solution‐cast into flexible and tough films. They had T g values in the 150–237°C range and showed no significant weight loss below 400°C in air and nitrogen atmosphere.