Fluorous Dispersion Ring-Opening Metathesis Polymerization

We herein report the development of a fluoropolymer dispersion ring-opening metathesis polymerization to polymerize a heavily fluorinated (>60 wt % fluorine) norbornene without the utilization of expensive fluorinated solvents. A fluorinated block copolymer was synthesized and used as a stabilizer, the addition of which allowed for a complete monomer conversion within minutes to yield fluorous polynorbornenes with predetermined molecular weights and low molecular weight distributions (D̵s) over a wide range of monomer/catalyst ratios. The products were obtained as spherical particles, the size of which could be controlled over the range of 0.1–7 μm, and the block copolymer stabilizer was found to occupy a particle surface area of 15.5 nm2 per molecule. The highly fluorinated polymers were shown to have a very low refractive index, and rheological studies showed a well-defined relationship between zero-shear viscosity and the degree of polymerization, allowing for the determination of critical entanglement molecular weights.