A hyperbranched aromatic fluoropolyester for photonic applications

A highly fluorinated hyperbranched aromatic polymer was prepared by a mild one-step polyesterification of an AB₂ type monomer at room temperature using dicyclohexylcarbodiimide and 4-(dimethylamino)pyridium 4-toluenesulfonate as the condensation agents. It was then postfunctionalized with thermally cross-linkable aromatic trifluorovinyl ethers to enhance its thermal and mechanical properties for optical waveguide applications. The cross-linked polymer exhibited low optical loss (0.58 dB/cm at 1310 nm) and high thermal stability with less than 5 wt% loss at 470°C. The degree of branching, as determined by quantitative ¹³C NMR spectroscopy, was found to be 0.50.