Novel polymers containing alternating perfluorocyclobutane and aromatic ether subunits are prepared from aryl poly(trifluorovinyl ether) monomers via the thermal [2π + 2π] dimerization of the trifluorovinyl ether functionality. A model study is described, which probes the nature of the perfluorocyclobutane rings formed during the polymerization reaction. The bifunctional monomer 4,4′‐bis(trifluorovinyloxy) biphenyl and the trifunctional monomer 1,1,1‐tris(4‐trifluorovinyloxyphenyl)ethane are prepared and polymerized to provide thermoplastic and thermoset polymers, respectively. Characterization of the mechanical and dielectric properties of these new polymers is presented. © 1993 John Wiley & Sons, Inc.

The synthesis and characterization of siloxane-containing perfluorocyclobutane (PFCB) aromatic polyethers, a new class of fluorosiloxane polymers possessing a well-defined linear structure of alternating disiloxanyl-p-phenylene (cis/trans)-1,2-disubstituted perfluorocyclobutyl ether linkages with known fluoroolefin end groups, is described. The unexpected formation of an aryl Grignard reagent from 4-[(trifluorovinyl)oxy]bromobenzene (2) allowed for the high-yield synthesis of 4-[(trifluorovinyl)oxy]phenyldimethylsilane (3) which was dehydrogenatively hydrolyzed in situ and condensed to bis[1,3-[4-[(trifluorovinyl)oxy]phenyl]]-1,1,3,3-tetramethyldisiloxane monomer (4). Thermal cyclopolymerization in the bulk produces poly(1,1,3,3-tetramethyldisiloxanyl-p-phenylene-1-oxaperfluorocyclobutylene-2-oxa-p-phenylene) (5) as a clear, flexible, and thermally stable elastomeric film. Copolymerization of 4 with a trifunctional PFCB monomer gives a toughened thermoset with good thermal stability. Monomers and polymers were characterized by 1H, 13C, and 19F NMR and FTIR spectroscopy. Number-average molecular weights were determined by gel permeation chromatography and, when possible, quantitative 19F NMR end group analysis. Synthesis, characterization, thermal analyses, and current scope of PFCB polymer chemistry are discussed.

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