' are the same or different and are a value of 0 or greater, provided that at least one of m', n', or p' is a value of at least 2; z is a value of 0 or greater; each R4 is the same or different and is a substituted or unsubstituted divalent hydrocarbon residue; each R5 is the same or different and is a substituted or unsubstituted divalent hydrocarbon residue; each R6 is the same or different and