The copolymerization of aryl bis‐ and tris‐trifluorovinyl ether monomers yields aromatic perfluorocyclobutyl (PFCB) polymers, via thermally initiated step‐growth cycloaddition chemistry. PFCB polymers and their copolymers enjoy a unique combination of attributes well suited for applications in photonic technologies, such as broad tailorability of refractive indices and thermo‐optic coefficients, low transmission losses at 1300 and 1550 nm, high thermal, mechanical, and optical stability, and excellent melt and solution processability. Planar PFCB structures can be processed by direct micro‐transfer molding, which is a first step towards rapid soft‐lithographic fabrication of polymer planar lightwave circuits. Copolymerization chemistry and processing parameters and characterization, including thermal (Tg = 120–350 °C) and optical properties (refractive indices from 1.443 to 1.508 at 1550 nm; thermo‐optic coefficients dn/dT = –7×10–5 K–1 to –1.5 × 10–4 K–1), birefringence (< 0.003), and temporal stability of refractive index, are described.
Bis‐ortho‐diynylarene (BODA) monomers, prepared from common bisphenols in three high yielding steps, undergo free‐radical‐mediated thermal polymerization via an initial Bergman cyclo‐rearrangement. Polymerization is carried out at 210 °C in solution or neat with large pre‐vitrification melt windows (4–5 h) to form branched oligomers containing reactive pendant and terminal aryldiynes. Melt‐ and solution‐processable oligomers with weight‐average molecular weight Mw = 3000–24 000 g mol–1 can be coated as a thin film or molded using soft lithography techniques. Subsequent curing to 450 °C affords network polymers with no detectable glass transition temperatures below 400 °C and thermal stability ranging from 0.5–1.5 % h–1 isothermal weight loss measured at 450 °C under nitrogen. Heating to 900–1000 °C gives semiconductive glassy carbon in high yield. BODA monomer synthesis, network characterization and kinetics, processability, thin‐film photoluminescence, and thermal properties are described.
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