Development of Benzimidazole‐Containing Thermosetting Imide Oligomers With Enhanced Thermal Stability and Adhesive Properties

ABSTRACT In this work, phenylethynyl‐terminated imide oligomers incorporating benzimidazole structures were synthesized and their structures were characterized using Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), and proton nuclear magnetic resonance ( 1 H NMR). The solubility, curing behavior, thermal stability, thermomechanical properties, and adhesive performance were systematically evaluated. Different dianhydride structures and isomer ratios were utilized to optimize the performance of the oligomers. Thermogravimetric analysis (TGA) revealed 5% weight loss temperatures ( T 5% ) exceeding 520°C under both nitrogen and air atmospheres, demonstrating excellent thermal stability. Lap shear strength ( LSS ) testing showed that oligomers based on 4,4′‐oxydiphthalic anhydride (ODPA) exhibited superior adhesive performance, particularly at elevated temperatures. The glass transition temperature ( T g ) was significantly influenced by the ratio of 3,3′,4,4′‐biphenyltetracarboxylic dianhydride ( s ‐BPDA) to 2,3,3′,4′‐biphenyltetracarboxylic dianhydride ( a ‐BPDA), with a maximum T g of 482°C. These results underscore the potential of these oligomers for high‐performance adhesive applications in industries such as aerospace and electronics.