Rapid UV cross-linked polyimide films with enhanced mechanical and thermal properties

This study presents an innovative strategy for fabricating high-performance cross-linked polyimide films prepared from the monomers 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2′-bis(trifluoromethyl)benzidine (TFMB) via in-situ photosensitive functionalization at the poly(amic acid) precursor stage. Photo-cross-linkable methacrylate groups were grafted through esterification prior to low-temperature chemical imidization, enabling rapid UV-triggered curing within 30 s and restricting the maximum processing temperature to 200 °C. An optimal cross-linking degree of 50% yielded a tensile strength of 131.6 MPa with excellent fatigue resistance. The fluorinated films exhibited a transmittance of 76.9% at 400 nm, while the incorporation of 4,4′-oxydianiline (ODA) monomers further enhanced the strength to 148.3 MPa. The resulting films also showed a high glass transition temperature of 275.7 °C and an increased water contact angle of 93.7°. This precursor-level functionalization method provides a scalable platform for manufacturing advanced polyimide films with synergistically enhanced properties, making them promising for applications in flexible electronics and high-frequency devices.