Dielectric properties of diblock copolymers containing a polyarylene ether nitrile block and a polyarylene ether ketone block

The block copolymers poly(arylene ether nitrile ketone) (PENK) composed of a poly(arylene ether nitrile)s block and a poly(arylene ether ketone) block were prepared from biphenol, 2,6-dichlorobenzonitrile and 4,4′-difluorobenzophenone (DFBP) by the nucleophilic aromatic substitution reaction. The molecular structure of PENK was characterized by the Fourier transform infrared spectrum (FT-IR) testing. The properties of the PENK polymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) characterization, mechanical testing, dielectric and breakdown strength measurement. According to the DSC characterization, only one glass transition temperature (~ 216 °C) of all the polymers is observed and remained even treated at a temperature of 360 °C, indicating that the block polymer PENK has a homogeneous morphology. In addition, PENK polymers exhibit excellent thermal stability and mechanical strength, the thermal decomposition temperature of the polymers ranges from 530 to 535 °C, and the tensile strength of them ranges from 100 to 117 MPa. The energy storage density of PENK films is closely related to the molecular structure of them. The results show that with the increase of DFBP, the energy storage density increases from 0.62 to 1.11 J/cm³.