Chain Polymerizations Synthesis of Fluoropolymers

Fluoropolymers are usually obtained through heterogeneous (emulsion or suspension) polymerization techniques in aqueous systems. As a consequence of the 

In this context, dense C02 represents a sustainable alternative to such volatile organic compounds (VOCs), as demonstrated implicitly by the huge investments made over the past few years, both in the USA (i.e., the cooperation of DuPont with University of North Carolina) and in the European Union (European Research Grants Superpol and Ecopol), in investigating the use of scC02 for the production of fluorinated polymers. 

Poly(vinylidene fluoride) (PVDF) is the second most important thermoplastic within the fluoropolymer family after PTFE. Although, both the thermal and chemical stability of PVDF are somewhat lower compared to PTFE, the hydrogenated polymer can be more easily processed with conventional equipment, and it offers an advantageous compromise between quality and price. When the 

Other groups [99, 100] investigated the possibility of carrying out a surfactant-assisted polymerization of VDF in scC02, using diethyl peroxydicarbonate (DEPDC) as a free radical initiator, with the aim of testing several perfluoropolyether compounds synthesized by Solvay Solexis as stabilizers. When ammonium carboxylate derivatives were used, an effective stabilization of the polymer particles was obtained, and the polymer was collected from the reactor with yields of up to 63%. This corresponded to a solid content in the reactor of 220 g I in the form 

TFE and VDF may be copolymerized with suitable comonomers in order to obtain macromolecular materials with improved end-use properties. One fluori-nated monomer that was copolymerized under mild conditions (308 K and 9-11 MPa) was perfluoropropyl-vinylether (PPVE) (CF3CF2CF2OCF=CF2). The copolymer was obtained in the form of a free-flowing powder, with almost quantitative yields moreover, its composition could be altered by changing the molar ratio of the comonomers in the feed. Interestingly, chains were synthesized with molecular weights greater than that of the commercial product with a concentration of carboxylic acid or acid fluoride end groups similar to those detected in polymers prepared in CFCs [101], 

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