Porous amino-functionalized silica/polyimide composites via in-situ polymerization: Dielectric, mechanical, and water resistance enhancement

In order to meet the needs of modern communication technology, polyimide films with low dielectric constant and excellent comprehensive properties need to be prepared. In this study, fluorinated polyimide (SiFPI) and ether-containing polyimide (SiBPI) were synthesized via siloxane modification. On this basis, amino-functionalized porous silica particles were used as reinforcing fillers. Porous polyimide composite films (SiFPI/SiO 2 and SiBPI/SiO 2 ) were prepared by incorporating silica particles into the polyimide matrix via in-situ polymerization. The effects of silica content on the dielectric, mechanical, thermal, and water resistance properties of the composite films were systematically investigated and discussed. The results showed that at the silica content of 6 wt%, the dielectric constant of the SiFPI/SiO 2 composite decreased from 2.90 to 2.33 at 1 MHz, while that of the SiBPI/SiO 2 composite decreased from 2.92 to 2.37. Both composite films also exhibited high mechanical performance, with the tensile strength of the SiFPI/SiO 2 and SiBPI/SiO 2 composites reaching 136.2 MPa and 111.3 MPa, respectively. With the silica content increasing, both composite films exhibited a notable reduction in water absorption, which remained below 0.95%. Moreover, the composite films maintained comparable thermal stability to that of the pure film.