Perfluorocyclobutane Aromatic Polyethers. Synthesis and Characterization of New Siloxane-Containing Fluoropolymers

Abstract

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.

Synthesis of novel fluorinated polymers: facile carbon–carbon bond formation aided by fluorine substituents

“…6 The anionic polymerization was conducted with several anionic initiators and was shown to afford homopolymers with the highest molecular weight of 1.9Â10 4 with an extremely narrow molecular weight distribution and a low yield when initiated with cesium tert-butoxide and allowed to proceed at 60 1C for 72 h in toluene. Poly(trifluorovinylbenzene) was produced by the initiation of diethyl(ethyl cyanoacetato)aluminum with 7% as the highest yield.…”

Science and technology of perfluorocyclobutyl aryl ether polymers

“…[17][18][19] The aryl TFVE-functionalized compound 11 can be easily prepared from inexpensive 4-bromophenol in high yield utilizing the aforementioned alkylation-reduction methodology. The reactive intermediate is prepared from 10 using well-established Grignard or organolithium halogen-metal exchange chemistry with the fluorinated olefin intact.…”

“…Condensation of aryl TFVE dimethylchlorosilane [R ¼ Si(CH 3 ) 2 H] via dehydrogenative hydrolysis/methanolysis yielded the first siloxanecontaining aryl TFVE monomer for the preparation of PFCB aryl ether fluorosilicones (12). 19 Disilanol monomers containing PFCB aryl ether rings have also been prepared to produce fluorosilicones via condensation polymerization. 20 Similarly, silicon-enriched PFCB aryl ether network polymers (23) were prepared by Kim and Scheme 1.…”

“…12). 149 More recent work encompassed the preparation of improved thermally stable, solution processable linear POSS PFCB aryl ether polymers with POSS appended to the chain ends (19) 28 and as pendants (35). 150 Blending PFCB aryl ether polymers 5 or 6 with fluorinated POSS has also enhanced the water and oil repellency of the homopolymer.…”

“…26 Harris and Choi 27 showed the construction of imide-functionalized PFCB aryl ether polymers (15) can be prepared starting from the amine aryl TFVE monomer (R ¼ NH 2 ). The ability to couple the aryl TFVE carboxylic acid of 11 (R ¼ COOH) with primary alcohols was used for the preparation polyhedral oligomeric silesquioxanes (POSS) PFCB aryl ether copolymers (19). 28 Similarly, Jen has shown coupling with the aryl TFVE carboxylic by anchoring chromophore-functionalized oligomers via postesterfication to afford polymer 21 and other analogous dendrimers.…”