| abstract |
A composition curable to a thermally reversible rubber comprises (i) a strong acid catalyst having a pKa of less than about -9, (ii) at least one polycyclosiloxane containing at least one polyfunctional siloxane unit, and (iii) at least one polysiloxane selected from the group consisting of a linear polydimethylsiloxane; a polydimethylcyclosiloxane containing from about 6 to about 50 silicon-oxygen bonds; a linear or cyclic block copolymer of polydimethylsiloxane and a non-siloxane organic polymer; and a linear or cyclic random copolymer of a siloxane of the formula Si(R)(R1)O wherein R and R1 are different and are selected from the group consisting of hydrogen, C1-C18 hydrocarbon and C2-C18 hydroxyalkyl, wherein the catalyst comprises from about 0.05 to about 0.5 wt % of the composition, and the concentration of polyfunctional siloxane units is at least about two times the catalyst concentration in the composition, but no more than about 0.27 molar. Novel compounds useful as the polycyclosiloxane component of the composition are also provided. |