TFVE monomer

A new synthetic strategy for incorporating a wide variety of NLO chromophores into PFCB polymers has been developed by Ma et al. [ 100]. The chromophore loading can be tuned by varying the ratio of chromophore-substituted di-TFVE monomer and the tri-TFVE inert monomer. The obtained mixture is then prepolymerized at 150°C, spin-coated to obtain high-quality films, and efficiently cross-linked at 180-250°C. All resulting NLO PFCB (Fig. 4.11) thermosets possess excellent solvent resistance,... 

Scheme 6.23 Thermal [2h-2] cyclodimerizatlon of aryl TFVE monomers. Taken from Ref. [98],...

Condensation of aryl TFVE dimethylchlorosilane via dehydrogenerative hydrolysis/methanolysis yielded a siloxane containing aryl TFVE monomer for the preparation of PFCB aryl ether fluorosilicones [99], Rizzo et al. prepared two disilanol monomers containing perfluorocyclobutane rings, l,2-bis[4-(dimethylhydroxysilyl)phenoxy]-1,2,3,3,4,4-hexalluo-rocyclobutane and l,2-fiw[3-(dimethylhydroxysilyl)... 

Herein we review details on synthesis of the TFVE monomer CF2=CFOCF2CF (CF3)0CF2CF2—S02N(Na)S02Cp3 9, its copolymers with TFE10, and some physical properties of these polymers. Electrochemical characterization of earlier versions of these polymers has been reported previously [21-24], as well as some preliminary reports on their preparation and properties [14, 25-30]. 

TFVE monomer could only be added after 3 h of polymerization. 

Our ongoing strategy to develop new fluorosilicone materials has been to combine the well known preparative chemistry of silicon containing compounds with the relatively new development of perfluorocyclobutane (PFCB) aromatic ether polymers. PFCB materials are prepared by the thermal cyclodimerization of trifluorovinyl ether (TFVE) monomers." " Recently we developed a synthetic... 

Focus was then shifted to well established hydrosilation techniques " using readily available olefin functionalized phenols. The highly active Pt(0) complex, Pt2[(CH2=CHSiMe2)20]3 (Karstedt s catalyst), " was used under standard conditions and the siloxane bisphenol adduct of 2-allylphenol and tetramethyldisiloxane (Figure 3) was obtained as the pure p-adduct. The corresponding bis-TFVE derivative was then easily prepared by our standard method. When heated at 210°C, this new monomer provided the first siloxane containing PFCB polymer, as well as the first orr/io-substituted example. Moderate degrees of polymerization (Mn = 16000) and a Tg = -16 C were measured. 

Figure 10. Hydrosilation Polymerization of TFVE Di-olefin Monomers.

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. 

Thermal stability in nitrogen exceeded 400°C in most network cases which is characteristic of both siloxane and PFCB containing materials. Not shown here is the thermal oxidative stability for thermosets 11 -14 . In contrast to the TFVE reactive polymers prepared from mono-olefin TFVE derivatives, networks 11 -14 prepared from TFVE functionalized di-olefin monomers do not contain oxidatively unstable benzylic carbons. 

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