Radiopaque iodinated ethers of poly(vinyl iodobenzyl ether)s: Synthesis and evaluation for endovascular embolization

Leachable-free radiopaque iodinated polymers were designed as long-lived embolization materials visible by X-ray tomography. This is a definite improvement over liquid embolics incorporating either radiopaque inorganic particles or iodinated polymers having hydrolysable ester bonds. Grafting 4-iodobenzyl or 2,3,5-triiodobenzyl groups to poly(vinyl alcohol) (PVAL) yields iodobenzyl ethers of PVAL having iodine contents in the range 40–70 wt %. Their solubility in solvents accepted for medical devices (DMSO and NMP), viscosity of concentrated solutions, precipitation behavior, radiopacity, and stability with respect to sterilization and hydrolysis were assessed. The solvent NMP allows the preparation of concentrated solutions of suitable viscosity for their application as liquid embolics. Precipitation in water yields a cohesive mass of material that can plug vascular malformations. A rationale to the properties is given in terms of the Hansen contributions to the Hildebrand solubility parameters. Iodobenzyl ethers of PVA resist hydrolysis whereas their corresponding iodobenzoyl esters leach iodinated fragments.