Cardo fluorene based semifluorinated co-poly(arylene ether)s: Synthesis, characterization and dielectric properties

• New semifluorinated co-poly(arylene ether)s (Co-PAEs) were prepared.
• Co-PAEs showed low dielectric constant (<2.5) and high thermal stability.
• FESEM images indicated formation of nano-porous polymer membranes.

Three new co-poly(arylene ether)s (PAE) containing cardo fluorene moiety in the main chain and pendent trifluoromethyl group have been synthesized by one pot high temperature polycondensation reaction using two kinds of bis-hydroxy compound, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl)fluorene (DMHF), bisphenol A (BPA) and three different bis-fluoro monomers. The structures of the resulting co-PAEs were investigated by FT-IR and NMR spectroscopy. All the polymers showed good solubility in common organic solvents and high weight average molecular weight up to 443,000 g/mol. Flexible, transparent and mechanically strong films were obtained after solution casting from N,N-dimethylacetamide (DMAc). The polymers exhibited reasonably high thermal stability (Td10, in the range of 459–485 °C) and high glass transition temperature (215–228 °C). The PAE membranes also revealed good optical transparency (λcut-off = 350–370 nm) along with very small water absorption (0.38–0.49%) after 72 h immersion in water. Furthermore, the PAE membranes showed low dielectric constants with the values in the range of 2.25–2.42 at room temperature and at 1 MHz frequency, measured from their capacitance.

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