Aromatic hybrid fluorosilicones, such as perfluorocyclobutane
aromatic poly
ethers, have higher thermal stability than typical polysiloxanes. While these poly
ethers decompose by homolytic
cleavage of the oxygen–perfluorocyclobutane bond, the enhanced thermal stability of the poly
ethers may, in part, arise from this oxygen through the anomeric effect. To determine the effect of the
ether oxygen on thermal stability, two perfluorocyclobutane
aromatic units, one with and one without the oxygen, were modeled. To confirm the results experimentally, a series of hybrid fluorosilicones based on the latter were synthesized by thermocyclodimerization of 1-bromo-4-(trifluorovinyl)benzene, metal–halogen exchange, and condensation with one of 1,3-dichlorotetramethyldisiloxane; 1,7-dichlorooctamethyltetrasiloxane; or chlorine-terminated poly(dimethylsiloxane). The degradation temperature (
T1%) was lower (
![not, vert, similar](http://www.sciencedirect.com/scidirimg/entities/223c.gif)
240 °C) than the comparable poly
ethers (
![not, vert, similar](http://www.sciencedirect.com/scidirimg/entities/223c.gif)
430 °C). These results demonstrate the importance of the
ether oxygen to the stability of perfluorocyclobutane
aromatic poly
ethers through a number of effects including the anomeric effect and enhancing the strength of the silicon-
aromatic bond.