In situ synthesis of PMIA/SiO2 nanocomposites and porous PMIA films via SiO2 etching: thermal, mechanical, and dielectric properties

Poly (m-phenylene isophthalamide) (PMIA) is a high-performance polymer known for its exceptional thermal stability, mechanical strength, and chemical resistance, making it an ideal candidate for advanced material applications. This study presents the synthesis, characterization, and analysis of poly (m-phenylene isophthalamide) (PMIA)/SiO 2 nanocomposites and porous PMIA films. PMIA/SiO 2 nanocomposites were prepared using in situ interfacial polycondensation, incorporating 3-, 5-, and 7-wt% SiO 2 nanoparticles. Nanocomposite films were fabricated through a controlled casting method, followed by etching SiO 2 particles with hydrofluoric acid to create porous PMIA films. Enhancement of the PMIA/SiO 2 nanocomposites exhibited improved inherent viscosity, indicating high molecular weight and efficient polymerization. Fourier Transform Infrared (FTIR) spectroscopy confirmed the successful integration of SiO 2 into the PMIA matrix. Scanning Electron Microscopy (SEM) revealed uniform pore distribution in the porous films, with pore size increasing with higher SiO 2 content. Thermogravimetric analysis (TGA) demonstrated enhanced thermal stability of PMIA/SiO 2 composites, with degradation temperatures increasing from 440 °C for pure PMIA to 460 °C for composites containing 7-wt% SiO 2 . Mechanical testing indicated that PMIA/SiO 2 composites with 5-wt% SiO 2 achieved optimal tensile strength (31.8 MPa) and elongation at break (30.1%), while higher SiO 2 content resulted in reduced mechanical performance due to particle agglomeration. The dielectric constants of these porous films remained consistently lower than those of their nonporous counterparts throughout the frequency range of 1 Hz to 1 MHz. This work highlights the potential of PMIA/SiO 2 nanocomposites and porous PMIA films for advanced applications requiring thermal and mechanical resilience, with tunable properties achieved through SiO 2 content variation.