Preparation and properties of transparent poly(aryl ether ketone) films with low dielectric constant

The objective of this study is to prepare a new poly(aryl ether ketone) (PAEK) with low dielectric constant, high transparency and heat resistance by introducing fluorine atoms and phenolphthalein (PHPH) groups into the polymer backbone. The chemical structure of PAEK random copolymers was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR) and X-ray diffraction (XRD),, and the molecular weight of PAEK was determined by gel permeation chromatography (GPC). It is found that these random copolymers are soluble in common organic solvents, especially low boiling point solvents, such as CHCl3, tetrahydrofuran (THF) and dimethylacetamide (DMAc). Transparent, uniform and flexible films were prepared by casting from DMAc solvent. The PAEK copolymers exhibit high glass transition temperature (163-220 & DEG;C by differential scanning calorimetry (DSC) and 168-227 & DEG;C by dynamic mechanical analysis (DMA)) and thermal stability with 5% weight loss temperatures of 461-525 & DEG;C. The PAEK films show good mechanical properties with tensile strengths of 50-62 MPa. The dielectric constant (k) is only 2.31-3.08, and the loss tangent is only 0.003-0.009 at 1 MHz. All films exhibit excellent optical transparency, their UV cutoff wavelength is shorter than 386 nm, and the transmittance at 450 nm is higher than 80%.