US 10,921,710 B2  23  24  (5)  -continued  Herein  RA  is as defined above. R 3  and R 4  are each  independently hydrogen or hydroxyl. Y is a substituent  group containing a lactone structure different from formula  (1) or a substituent group containing a sultone structure. Z  is hydrogen, a C$_{1 }$-C$_{15 }$ fluorinated hydrocarbon group, or a 15  C$_{1 }$-C$_{15 }$ fluoroalcohol-containing substituent group.  Examples of the recurring units having formula (3) are  given below, but not limited thereto. Herein  RA  is as defined  above.  Examples of the recurring units having formula ( 4) are 65  given below, but not limited thereto. Herein  RA  is as defined  above.  tto  H  H 