Preparation of Porous Poly (M-Phenylene Isophthalamide) Films with Reduced Dielectric Constants Using Wet Phase Inversion Method Optimization and Performance Evaluation

Poly (m-phenylene isophthalamide) (PMIA), a key aromatic polyamide, is widely used for its outstanding mechanical strength, high thermal stability, and excellent insulation properties. However, different applications demand varying dielectric properties, so tailoring its dielectric performance is essential. PMIA was first synthesized in this study, followed by introducing pores and developing porous PMIA films and PMIA-based composites with reduced dielectric constants. Porous PMIA films were fabricated using the wet phase inversion process with N, N-dimethylacetamide (DMAC) solvent and water as the non-solvent. The impact of casting solution composition and coagulation bath temperature on pore structures was analyzed. A film produced with 18% PMIA and 5% LiCl in a 35 ℃ coagulation bath achieved the lowest dielectric constant of 1.76 at 1 Hz, 48% lower than the standard PMIA film, which had a tensile strength of 18.5 MPa and an initial degradation temperature of 320 ℃.