Electrospun <scp> SiO ₂ </scp> /polyimide materials based on the water‐soluble polyamiс acid salt <scp>PMDA</scp> ‐ <scp>ODA</scp> with an ultra‐low dielectric constant

Abstract In the 5G field, there is a growing demand for materials with ultra‐low dielectric constant values that are able to maintain their dielectric and mechanical characteristics in a wide range of temperatures and frequencies of electric fields. In this work, heat‐resistant composites based on the salt of polyamic acid from pyromellitic dianhydride PMDA and 4,4′‐oxydianiline ODA modified with SiO 2 particles were obtained by electrospinning. The prepared materials demonstrated ultra‐low permittivity. The dielectric constant (ε′) of the composite nonwoven materials varied from 1.74 to 1.35 with increasing SiO 2 content. The interaction between SiO 2 and the polyimide matrix led to a decrease in the ε′ value with increasing SiO 2 concentration. The main relaxation transitions of PI/SiO 2 composites in a wide temperature range (from 100°C to 480°C) were determined by dynamic mechanical analysis. With an increasing SiO 2 fraction, the glass transition temperature shifted toward a higher temperature region (from 365°C to 377°C) indicating an interaction between the matrix and the filler. Highlights Electrospun PI/SiO 2 materials with an ultra‐low dielectric constant were prepared. The presence of the SiO 2 filler reduced the dielectric constant of the composites. The presence of the SiO 2 filler increased the glass transition temperature of the composites.