A compound has formula (I): wherein in formula (I), Z is a y valent C1-20 organic group, A1 and A2 are each independently ester containing or non-ester containing and are fluorinated or non-fluorinated, and are independently C1-40 alkylene, C3-40 cycloalkylene, C6-40 arylene, or C7-40 aralkylene, and A1 contains a nitrile, ester, or aryl substituent group alpha to the point of attachment with sulfur, L is a heteroatom or a single bond, X1 is a single bond, —O—, —S—, —C(═O)—O—, —O—C(═O)—, —O—C(═O)—O—, —C(═O)—NR—, —NR—C(═O)—, —NR—C(═O)—NR—, —S(═O)2—O—, —O—S(═O)2—O—, —NR—S(═O)2—, or —S(═O)2—NR, wherein R is H, C1-10 alkyl, C3-10 cycloalkyl or C6-10 aryl, Q− is an anionic group, G+ is a metallic or non-metallic cation, and y is an integer from 1 to 6. A polymer having end groups comprising the reaction product of the compound of formula (I), and a method of making a polymer, are also disclosed.