| abstract |
A polydimethylsiloxane which has both low reactivity endgroups and high reactivity endgroups. These polydimethylsiloxanes are useful for making sealants with reduced modulus. An example of these polydimethylsiloxanes is one having low reactivity endgroups of the formula n n ZR.sub.2 SiO-- n n where Z is alkoxy, acyloxy, or N-methylbenzamido, and R is methyl or vinyl and high reactivity endgroups having a formula n n Y'.sub.h Y.sub.b R".sub.(3-b-h) SiO-- n n in which b is 1, 2, or 3, h is 0 or 1, b+h is 2 or 3, R" is a monovalent hydrocarbon radical, and each Y is an acyloxy groups or N-methylbenzamido, and Y' is an alkoxy groups. |