Synergistic Enhancement of Thermal, Dielectric, and Alkaline Corrosion Resistance in Poly(Ether Imide)s via a Cross-Linking Strategy

To address the long-standing trade-off among dielectric properties, thermal stability, and chemical resistance in conventional poly(ether imide)s (PEIs), a facile and effective molecular design strategy was proposed. This is achieved by incorporating two newly synthesized, inherently alkyne-functionalized active molecules (PF-ISO and PF-BIQ) into a PEI matrix, followed by thermal curing to construct robust cross-linking films exhibiting a remarkable glass transition temperature ( T g ) of up to 387 °C (PEI/BIQ-7), representing a 40.7% increase over that of the pristine PEI (275 °C), while the coefficient of thermal expansion (CTE) is reduced by 18.4% (PEI/ISO-7). The temperature at 10% weight loss ( T d10% ) reaches 532 °Cwith a high char yield of 54% at 800 °C (PEI/ISO-7). Concurrently, for PEI/BIQ-7, the tensile strength and Young’s modulus are enhanced by 25% (105 MPa) and 30.6% (2.35 GPa), respectively, without compromising desirable flexibility. Most importantly, the dielectric constant ( D k ) is significantly reduced from 2.90 to 2.54 with a low dielectric loss ( D f = 0.002–0.008) over a broad frequency range. Furthermore, the PEI/BIQ-7 films exhibit improved hydrophobicity and superior alkali resistance, retaining up to 86% of their original mechanical strength after harsh alkaline exposure. This work provides a versatile and scalable method for developing high-performance PEIs suitable for microelectronic packaging and high-frequency communication devices.