er form an epoxy group and Q is ##STR61## and n is 0 and p is 0 and r is 1 or n is 1 and p is 1 and r is 1 or Q is a bond between O and Q and n is 0 and p is 0 and r is 1 and p is 0 and r is 1, or Q is ##STR62## and n is 0 and p is 0 and r is 1, or Q is ##STR63## and p is 1 and n is 1 and r is 0 and t is 1 or p is 0 and n is 1 and r is 0 and t is 0, and R1 and R2 are each independently selecte