Low‐Temperature Fabrication of High‐Performance Cross‐Linked Polyimide Films via Rapid Ultraviolet Irradiation

ABSTRACT

This study develops a high‐performance cross‐linked polyimide film through an innovative strategy combining low‐temperature chemical imidization and rapid ultraviolet (UV) irradiation. To overcome the high‐temperature limitations of traditional thermal imidization, a photosensitive precursor was synthesized by copolymerizing 4,4′‐oxydiphthalic anhydride (ODPA), 1,3‐bis(4′‐aminophenoxy)benzene (1,3,4‐APB), and 3,5‐diaminobenzoic acid (DABA), followed by grafting 2‐hydroxyethyl methacrylate (HEMA) onto the polyimide backbone via Steglich esterification. This molecular design enables a complete synthesis at low temperatures and facilitates rapid photo‐cross‐linking, forming a dense network within 30 s under UV light. Subsequent film drying and curing require only 200°C. The resulting cross‐linked polyimide films exhibit synergistically enhanced properties proportional to the cross‐linking density. Optical transmittance at 400 nm wavelength significantly increased by 189%, attributed to the suppression of charge‐transfer complexes. Thermal stability improved, with the glass transition temperature rising to 272.6°C and residual carbon content exceeding 60% at 800°C. Tensile strength reached 105.4 MPa while maintaining tunable flexibility, and hydrophobicity was enhanced, evidenced by a contact angle of 79.8°. This methodology provides an energy‐efficient, scalable platform for next‐generation applications in flexible electronics and advanced devices, fundamentally addressing the thermal compatibility issues of conventional polyimides.