Synthesis and Properties of Aromatic Polyimides Derived from 2,2,'3,3'-Biphenyltetracarboxylic Dianhydride

摘要

2,2,'3,3'-Biphenyltetracarboxylic dianhydeide (2,2,'3,3'-BPDA) was prepared by a coupling reaction of dimethyl 3-iodophthalate. The X-ray single-crystal structure determination showed that this dianhydride had a bent and noncopolanar structure, presenting a striking contrast to its isomer, 3,3,'4,4'-BPDA. This dianhydride was reacted with aromatic diamines in a polar aprotic solvent such as N,N-dimethylacetamide(DMAc) to form polyamic acid intermediates, which imidized chemically to polyimides with inherent viscosities of 0.34-0.55 dL/g, depending on the diamine used. The polyimides from 2,2,'3,3'-BPDA exhibited a good solubility and were dissolved in polar aprotic solvents and polychlorocarbons. These polyimides have high glass transition temperatures above 283degC. Thermogravimetric analyses indicated that these polyimides were fairly state up to 500degC, and the 5% weight loss temperatures were recorded in the range of 534-583degC in nitrogen atmosphere and 573-561degC in air atmosphere. All polyimides were amorphous according to X-ray determination.