Microstructure and Properties of Polyimide /Monodispersed Colloidal Silica Hybrid Films Prepared by Sol–Gel Process

Abstract

In this study, the polyimide-silica hybrid thin films, 6FDA-6FpDA-4ABA/SiO2 (FS0-FS50) were prepared from the 12nm colloidal silica and polyimide bearing acid endgroups. During the preparation, without any additional coupling agents or chelating ligands were used. The strong interactions between carboxylic acid coordinating with silica were believed to prevent the macrophase separation. TGA analysis showed that the thermal decomposition temperatures (Td) incresased with increasing the silica content. UV-VIS spectra showed that the cutoff wavelength of prepared hybrid films could be tunable through the silica content. The n&k analysis showed that the refractive index (n) of PS hybrid films were in the range of 1.575-1.479, which could be controlled by the silica content. The extinction coefficients (k) are almost zero in the wavelength range of 300–900 nm, indicating the prepared hybrid films have an excellent optical transparency in the UV and visible region. TEM images showed that the particle size of silica in the hybrid thin films could be effectively controlled. The results of SEM and AFM showed that all the prepared hybrid films have a good planarity. It demonstrated that the prepared polyimide-silica hybrid thin films have an excellent film formability and planarity.