Fabrication of High-Performance Isocyanate-Based Polyimide Films via a Bridging Strategy

Isocyanate-based polyimide (IBPI) films synthesized using isocyanates and anhydrides as reactive monomers exhibit inferior mechanical performance, limiting their practical applicability. This study introduced 4,4′-oxidianiline (ODA) as a “bridging agent” to connect anhydride-terminated oligomer chain segments generated from diphenylmethane diisocyanate (MDI-50) and 4,4′-oxydiphthalic dianhydride (ODPA). A high-performance IBPI film with high solubility in common organic solvents was obtained via a bridging strategy; this work marked it as PI-X. The mechanical, thermal, and electrical properties of the PI-1.0 film were significantly improved. The tensile strength increased from 54.97 to 108.87 MPa, representing a 98% increase over that of the pure IBPI film. The temperature at 5% weight loss increased from 461 to 524 °C. Meanwhile, the dielectric constant and loss tangent decreased to 2.21 and 0.0047 at 1 kHz, respectively. These excellent performances show that IBPI films have great application prospects in the microelectronics industry.