Radiopaque monomers, polymers, microspheres, and methods related thereto

A method of embolization, comprising:

• injecting an embolic composition into a blood vessel of a patient, the composition comprising:
• a polymeric microsphere comprising a polymerized monomer having a structure according to Formula I:
• wherein n is 0-12 and wherein R is either an oxygen-containing moiety or a nitrogen-containing moiety;
• wherein the polymeric microsphere is non-resorbable within a body of the patient,
• wherein the polymeric microsphere is radiopaque, and
• detecting a location of the polymeric microsphere more than about 24 hours, more than about 48 hours, more than about a week, or more than about a month after introduction of the polymeric microsphere structure.