. . . " chain, or cyclic alkyl groups having 3 to 5 carbon atoms, phenyl group and Z groups, Z is a group selected from the following: trimethyl siloxy, pentamethyl disiloxanyl, heptamethyl trisiloxanyl, nonamethyl tetrasiloxanyl, bis(trimethylsiloxy)methyl siloxanyl or tris(trimethylsiloxy)siloxanyl a is an integer from 0 to 10, the total of a values is at least 2, n is an integer from 0 to abou" . .