Jul.  30,  2020  27  US 2020/0241417 Al  [0073]  In another preferred embodiment, the base polymer  may further comprise recurring units ( d) selected from units  derived from indene, benzofuran, benzothiophene, acenaph› thylene, chromone, coumarin, and norbonadiene, or deriva› tives thereof. Suitable monomers are exemplified below.  [0074]  Furthermore, recurring units (e) may be incorpo› rated in the base polymer, which are derived from styrene,  vinylnaphthalene, vinylanthracene, vinylpyrene, methyl› eneindene, vinylpyridine, and vinylcarbazole.  [0075]  In a further embodiment, recurring units (f) derived  from an onium salt having a polymerizable unsaturated bond  -continued  XR’ XR"  0  0  0  0  "(( C(  0  0  -continued  I~  I  XRA  ~  hi O  0  oyy  ,,  ~-"o  0  I  \_[  0  0  0 