Dielectric properties of poly(arylene ether nitrile ketone) copolymers

Abstract

A series of poly(arylene ether nitrile ketone) (PENK) random copolymers are successfully synthesized by the nucleophilic aromatic substitution polymerization of 2,6-dichlorobenzonitrile, 4,4′-difluorobenzophenone with various bisphenol monomers (4,4′-biphenol, bisphenol A, phenolphthalein, and hydroquinone). Compared with poly(arylene ether ketone), the PENK copolymers possess better solubility in polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, and so on. Because of the different molecular structures, the PENK copolymers exhibit thermal properties with their glass transition temperature ( T g) in the range of 171–237°C and 5% weight loss temperature ( T d) ranging from 409°C to 554°C. Moreover, all polymers with an intrinsic viscosity of approximately 1 dL/g show excellent film-forming properties and outstanding mechanical strength higher than 85 MPa. The temperature dependence of the dielectric constant and dielectric loss of all derived copolymers is stable before their T g. The breakdown strength of the hydroquinone-derived PENK copolymer is as high as 253 kV/mm, resulting in an energy storage density of 1.00 J/cm3. These solvent processable PENK copolymers are potential dielectric candidates for high temperature applications.