Sep. 10,2020  21  US  2020/0285149  Al  [0079]  Examples of the monomer from  which recurring  units (a2) are derived are shown  below, but not limited  thereto. Herein  RA  and R$^{42 }$are as defined above.  0  0  0  0  0  0  I  oy  R41  JR"  0  ’-R41  0  0/  XR’  0  0  XR"  0  0  XR"  0  0  }Gyo,R"  0  XR"  0  0  XR"  oy  0  0  0~ 0 /R"  0  0  0  0  0  0  0  X  R"  0  0/  £:  ..  0  0  XR"  XR"  0  0  0  0  $^{0 }$\  0  0  R41  -continued  0R42 