Such other ethylenically unsaturated monomer may be represented by the formula: ##STR23## wherein R1 is a hydrogen atom, a halogen atom or a substitute or unsubstituted C1 -C10 aliphatic hydrocarbon group, and R2 is a hydrogen atom, a halogen atom, a substitute or unsubstituted C1 -C10 aliphatic hydrocarbon group, a substituted or unsubstituted monovalent aromatic hydrocarbon group, an alkenyl gro