Microemulsion Polymerization for Producing Fluorinated Structured Materials

摘要

When perfluoropolyether microemulsions are used during polymerization of fluoropolymers, the structure of the reaction environment can be strictly controlled. In particular, the number and size of polymer particles in latexes can be set freely, yielding a number of advantages. First, as a result of radical segregation, terminations can be decreased without reducing polymerization rate: in this way high molecular weights are easily obtained also with poorly reactive monomers. Moreover, in combination with a reversible chain transfer mechanism based on iodine, particle segregation allows establishing pseudo-living polymerization conditions. In this situation formation of long branches in the polymer can be controlled by using bifunctional molecules that are able to link two different polymer chains to each other during polymerization. This is the so-called "branching and pseudo-living" technology. Finally, by co-coagulating latexes of different polymers prepared by microemulsion polymerization, very small particles and, thus, high interface areas are generated. In this way properties of different polymers, such as fluoroelastomers and fluorinated semicrystalline polymers, are matched effectively, generating new nanocomposite materials that exhibit outstanding properties. In this paper these results are reported and an overview of some novel sophisticated fluoropolymers obtained in microemulsion is given.