Masafumi Kohda

Preparation of poly (amide-imide)s derived from biphenyltetracarboxylic dianhydrides

Four new diimide-dicarboxylic acids (I-IV) were prepared by condensation of s- or a-BPDA with para- or meta-aminobenzoic acid. A series of aromatic poly( amideimide)s containing these diimide-dicarboxylic units was prepared by three methods: (1) acid chloride method, (2) triphenylphosphite method, and (3) one-pot method. A typical polymer of the series is readily soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), and pyridine (py) and could be cast into tough and flexible films. These were characterized by inherent viscosity, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) measurements. The glass transition temperatures of these polymers were in the range of 220-290°C, and the 5% weight loss temperatures were 450-500°C. Films prepared by casting from polymer solutions exhibited good tensile properties.

Preparation of polyimides derived from biphenyltetracarboxylic dianhydrides and aromatic diamines bearing alkylene spacers

Four series of aromatic polyimides (PIs V–VIII) composed of biphenyltetracarboxylic dianhydrides (BPDAs) and aromatic diamines bearing alkylene spacers were prepared by two methods. Most polymers could be readily prepared in a one-step method for the combination of a-BPDA with α,ω-bis(3-aminophenoxy)alkanes, a-BPDA with α,ω-bis(4-aminophenoxy)alkanes, and s-BPDA with α,ω-bis(3-aminophenoxy)alkanes. However, the polymerization of s-BPDA with α,ω-bis(4-aminophenoxy)alkanes gave powders. On the other hand, all four monomer combinations afforded the desired polyamic acid solution in a two-step method. These polymer solutions could be cast into tough and flexible films, which were characterized by their inherent viscosity, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical spectrometry measurements. The glass transition temperatures (Tgs) of the polymers were in the range of 110–240°C, but they were not clearly defined for PIs VIII and VI. The 5% weight loss temperatures were around 450°C for all prepared PIs. For PI VIII an “odd–even” behavior of the tensile properties of the films was detected, corresponding to the reported behavior of the melting temperatures.