Synthesis and properties of high performance polysulfone resin with low dielectric constant and dielectric loss

A series of novel cross-linkable PSF-6AF/DBA copolymers with different structure were successfully synthesized via nucleophilic aromatic substitution stepwise polymerization of 4,4′-dichlorodiphenyl sulfone (DCS) with hexafluorobisphenol A (6AF) and 4,4′-(propane-2,2-diyl)bis(2-allylphenol) (DBA) monomer. The 6AF and DBA moieties with a large number of pendant groups had been successfully introduced into the PSF polymer chain. Then, the PSF-6AF/DBA films were fabricated by casting the PSF-6AF/DBA/DMF solutions with the concentration of 10% on the clean glass plates, followed by heat-treating all the films at 300 °C for 4 h. The effects of both the component and cross-linking on the thermal, mechanical and dielectric properties of the obtained films were investigated in detail. Compared to PSF-6AF/DBA films, the cross-linked PSF-6AF/DBA (CS-PSF-6AF/DBA) films show high glass transition temperature (T_g= 184–197 °C) and outstanding mechanical strength (64–77 MPa). More importantly, all CS-PSF-6AF/DBA films display stable dielectric properties in the temperature range of 20–200 °C. The permittivity of CS-PSE-6AF/DBA film at 1 kHz is as low as 2.1, while the dielectric loss is only 0.007.