Novel polyethersulfone dielectric films with high temperature resistance, intrinsic low dielectric constant and low dielectric loss

In this work, a series of fluorene-containing fluorinated polyethersulfone (PES-6AF/BHPF) copolymers with high temperature resistance and intrinsic low dielectric constant (low- ε ) have been designed and synthesized from 4,4′-dichlorophenyl sulfone (DCS) and polyphenol. The performance of obtained PES-6AF/BHPF can be controlled and optimized by controlling the copolymers structure. The thermal and dielectric properties of PES-6AF/BHPF were evaluated comprehensively. The obtained PES-6AF/BHPF copolymers show high glass transition temperatures ( T g ) ranging from 200 to 260 °C, and 5% weight loss temperatures ( T d5% ) is stable up to 500 °C. The ε value of PES-6AF/BHPF-0% and PES-6AF/BHPF-100% are as low as 2.1 and 2.3, and the loss tangent (tan δ ) are only 0.0088 and 0.003 at 1 kHz, respectively. In addition, all of PES-6AF/BHPF films show good stability of dielectric properties in high temperature conditions. More importantly, the PES-6AF/BHPF copolymers are soluble in common solvents (such as DMAc, NMP, DMF, THF). The PES-6AF/BHPF copolymers are amorphous and can be easily cast into transparent and flexible films with tensile strength of 62–74 MPa and an elongation at break of 13.3–15.8%. The outstanding comprehensive properties made it possible to be the most promising polymer candidates for high-performance interlayer dielectrics.