157  US 9,360,753 B2  158  -continued  -continued  Polymer 7  ~  0  O  ~  ¢0  OH  Polymer 8  Polymer 6  Mw~9,900  Mw/Mn~ 1.86  Polymer 7  Mw~7,900  Mw/Mn~ 1.79  Polymer 8  Mw~7,800  Mw/Mn~l.78  ~  0.20  0  O  ~~  ¢  o  ~o  ~I  0  OH  HN-{  0  Polymer 9 