Fluorinated polymers possess a unique set of properties, ranging from extremely low surface energy, low dielectric constant and refractive index, high chemical resistance, and high thermal stability, the combination of which often make fluorinated polymers irreplaceable with their non-fluorinated counterparts. Many of the unique properties of fluorinated polymers, including their low solubility, become more conspicuous with increasing fluorine content, and precision synthesis of polymers containing majority fluorine content by weight thus remains a formidable challenge. We herein report a dispersion ring-opening metathesis polymerization (ROMP) of norbornenes with high fluorine contents (&gt; 50 wt. %) in the form of perfluoroalkyl chains. Using amphiphilic block copolymers bearing fluorinated blocks as steric stabilizers, the dispersion ROMP could be conducted using common organic solvents as the dispersing medium to afford highly fluorinated polynorbornene homopolymers with controlled molecular weights and low molecular weight distributions. Polynorbornenes with fluorine content of over 60 wt.% and molecular weight of over 500 kDa could be prepared in multigram scales using the polymerization, allowing for the studies into the material’s viscoelastic properties. The use of block copolymer dispersants led to the formation of fluoropolymer nano- and microparticles, the growth kinetics of which could be controlled by varying the concentratino of stabilizers. Furthermore, the dispersion ROMP could be extended to metal-free ROMP, allowing for the preparation of heavily fluorinated polynorbornenes using a visible light source and without the use of transition metal catalysts.

Synthesis of highly fluorinated polynorbornenes through dispersion polymerization

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