Siloxy-terminated fluoroelastomers were prepared through two-step reactions:(1) pentafluorophenol ester-terminated fluoroelastomer was synthesized by Steglich reaction using liquid carboxyl-terminated fluoroelastomer and pentafluorophenol as raw material; (2) the siloxy-terminated fluoroelastomer was prepared by substitution reaction with -aminopropyl triethoxysilane.The chemical structure of liquid carboxyl-terminated fluoroelastomer

pentafluorophenol ester-terminated fluoroelastomer and siloxy-terminated fluoroelastomers was characterized by FTIR

1H-NMR

19F-NMR and GPC.The carboxyl content measurement of pentafluorophenol ester-terminated fluoroelastomer was carried out by automatic potentiometric titration

and the conversion reaction is above 99.9%

which indicates that the reaction was completely conducted.The Siloxy-terminated fluoroelastomer can be cured at room temperature according to the mechanism of moisture-cure.Cured siloxy-terminated fluoroelastomer films with low Tg is usually obtained from higher molecular weight of fluoroelastomer.The cross-linked films obtained from higher molecular weight of fluoroelastomer have better tensile strength and elongation at break.The cured films have excellent chemical resistance

such as acid resistance

jet fuel oil resistance and cyclohexane resistance.And the cured films with higher molecular weight have better chemical resistance than those of the lower molecular weight.The observed contact angles were 91~114 for water and 89~111 for glycerol

which indicates that the cured films have good hydrophobic and hydrophilic properties.It is seen that the initial temperature (T5) of cured films appears in the range of 215 to 280 ℃ and the char yield at elevated temperature of 800 ℃ remains at 23.44%~38.69%.