Transparency and high heat resistance of cardo based poly(arylene ether)s for flexible plastic substrates

Abstract

New poly(arylene ether)s (PAEs) with both transparency and heat-resistance were prepared by the poly-condensation of 4-fluoro-4'(((fluorobenzoyl)phenyl)-oxy)diphenyl sulfone), an ordered-sequence aromatic dihalide, and cardo typed aromatic diols that contain fluorene, adamantane, or cyclohexane moiety. The resulting polymers were found to be amorphous by X-ray diffraction, and their glass transition temperatures ranged from 194 to $245^{\circ}C$. Based on the TGA data, they exhibited excellent thermal stability, showing 5% weight loss at 444-$496^{\circ}C$. They had low thermal expansion coefficients of 58-74 ppm at the temperature range of 50-$200^{\circ}C$ as well as good mechanical properties with moduli of 1,785-2,350 MPa, except for the PAE that contains the cyclohexane moiety (86 ppm at 50-$160^{\circ}C$; 1,070 MPa). The optical transmittance of the PAE films (ca. 40 ${\mu}m$ thick) was more than 70% at 450-800 nm and they also exhibited a very high refractive index in the range of 1.714-1.752 at 589 nm. In addition, their films showed a low water uptake of approximately 0.65% regardless of their chemical composition. Therefore, the newly developed PAEs show strong potential as plastic substrates for flexible devices for displays, solar cells and e-paper.