90  US 7,858,289 B2  89  OH  (RB-6)  OH  OH  Mw 8000  Mw/Mn 1.4  (RB-5)  oyo~ 0  Mw 15000  Mw/Mnl.4  -continued  OH  (RB-4)  OH  Mw2000  Mw/Mnl.4  (RB-3)  OH  oyo~ 0  Mw 1500  Mw/Mnl.4  (RB-2)  -continued 