Trifluorovinyl ether monomer

This chemistry was also performed on one trisphenol, 1,1,1 -tris(4-hydro-xyphenyl)ethane (THPE). The resulting tris(trifluorovinyl ether) monomer forms a thermoset polymer upon curing. 

Figure 3.3. Synthesis of trifluorovinyl ether monomers and perfluorocyclobutane aromatic ether polymers.

After isolation, the intermediate products were reacted with zinc in acetonitrile or a glyme solvent to provide the trifluorovinyl ether monomers. This reaction with zinc is also sensitive to the presence of protic substances in the reaction mixture, and forms the same tetrafluoroethyl ether by-product in an undesirable side reaction. The reaction of the 2-bromotetrafluoroethyl ether reactants with zinc involves the formation of zinc organometallic species as an intermediate, and this species is sensitive to hydrolysis by water or acidic substances (Figure 3.6). 

A more important use of HFPO is as an intermediate for the syntheses of a wide range of trifluorovinyl ether monomers that are used as comonomers in fluorinated plastics and elastomers. The general synthesis of this class of monomers is exemplified by the synthesis of perfluoromethyl vinyl ether (IV, PMVE) (Eq. 13.6). 

TABLE 13.1 Some Commercial Trifluorovinyl Ether Monomers Based on HFPO... 

He et al. have prepared phosphonated aiyl trifluorovinyl ethers containing flexible oligo(ethylene oxide) units and subsequently homopolymerized these monomers by thermal cyclopolymerization in bulk at 180 °C. The resulting polymer was treated with bromotrimethylsilane to obtain the phosphonic acid derivative. The phosphonated trifluorovinyl ether monomers were also copolymerized with tetrafluoroethylene via free radical pol3Tnerization in an autoclave at 70 °C using l,l,2-trichloro-l,2,2-tri-fluoroethane as solvent. Moreover, radical terpolymerizations of the same trifluorovinyl ether monomers were performed with mixtures of... 

To date, this method has become the most popular protocol to synthesize trifluorovinyl aromatic ether monomers. A variety of mono-, di-, and trifunctional trifluorovinyl ether monomers have been prepared simply by choosing the appropriate phenolic starting materials (Scheme 14.4), such as 3-trifluorovinyloxy-a,a,a-trifluorotoluene (2) [27], l,3-bis(trifluorovinyloxy)benzene (11) [27], 4,4 -bis (trifluorovinyloxy)biphenyl (6), [4] and l,l,l-tris(4-trifluorovinyloxyphenyl)ethane (14) [4]. Other monofunctional monomers include p-bromo(trifluorovinyloxy)... 

In this chapter, various synthesis routes for trifluorovinyl aromatic ethers are discussed. PFCB polymers are prepared via thermally activated [2+2] cycloaddition of aryl trifluorovinyl ether monomers. The cyclodimerizaton proceeds in a stereorandom fashion giving a roughly equal distribution of cis- and trans- stereoisomers. The PFCB technology can serve as a versatile materials platform for many industrial... 

Babb, D. A. Snelgrove, R. V. Smith, D. W., Jr. Mudrich, S. F. Novel Step-Growth Polymers from the Thermal (2p - -2pj Cyclopolymerization of Aryl Trifluorovinyl Ether Monomers-, ACS Symposium Series ACS Publications, 1996 pp 431 41. 

As mentioned earlier, exothermic polymerization of traditional trifluorovinyl ether monomers reach a measurable rate (DSC at 10 C/min) near 140°C and polymerizations are typically carried out at temperatures between 150-210°C. In contrast, the exothermic polymerization event for the crosslinking of TFVE functionalized silicones was delayed somewhat as expected due to the concentration of TFVE groups vs. traditional neat di- and trifunctional monomers. For example, DSC analysis (10°C/min) of reactive oligomer 11 exhibits an exothermic onset at 172°C and peak at 251°C. Selected thermal properties are summarized in Table 5. 

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