In some aspects, the present disclosure provides a hydrolytically stable iodinated multi-functional compound comprising: a multi-functional compound having functional groups that are reactive with a reactive group of a multi-arm polymer; an iodinated polyol having reactive moieties including two or more hydroxyl groups, and one or more iodinated aromatic groups; and a linker between a reactive moiety of the iodinated polyol and a functional group of the multi-functional compound, where the linker includes a carbamate linkage or a carbonate linkage.