Fluorinated Polymers Derived from Tetrafunctional Cyclic Siloxanes Possessing Low Optical Loss and High Thermo-Optic Property

We have prepared UV-curable fluorinated polymeric materials based on tetrafunctional cyclic siloxanes substituted with perfluoropolyether structure in order to have low optical loss, low birefringence, high thermo-optic coefficient, and good thermal stability. Perfluoropolyether structure with hydroxyl as one end and allyl as the other was prepared by reaction between fluorinated diols and allyl bromide. Then it was reacted with cyclic siloxane with platinum catalyst in a fairly high yield. The terminal hydroxyl was converted to acryl by reaction with acryloyl chloride. Transparent and stable films were obtained from the fluorinated monomers by UV irradiation. The photo-cured film was found to be thermally durable up to 300°C, where 2% weight loss occurred. The polymer films showed −1.59 × 10−4/K of thermo-optic coefficient, 0.0002 of birefringence, and 0.121 dB/cm of optical loss, which were measured by prism coupler at 1550 nm of laser source.