Expanding the Alternating Propagation-Chain Transfer-Based Polymerization Toolkit: The Iodo-Ene Reaction

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Thiol-ene and phosphane-ene polymerizations are established radical-mediated reactions.
• Iodo-ene reactions offer a new pathway for polymer synthesis.

Purpose of the Study:

• To explore radical-mediated iodo-ene reactions for polymer synthesis.
• To characterize the properties of resulting polymers, particularly radiopacity.
• To investigate the polymerization mechanism and kinetics.

Main Methods:

• Radical-mediated polymerization of perfluoroiodide- and vinyl-bearing monomers.
• Thermal polymerization of a diiodo/tetraene formulation.
• Visible-light photopolymerization of model iodo-ene monomers.
• Mid-infrared (mid-IR) spectroscopy for monitoring functional group consumption.

Main Results:

• A cross-linked, homogeneous polymer with high iodine content was synthesized via thermal polymerization.
• The synthesized polymer demonstrated approximately seven times greater radiopacity than aluminum.
• Photopolymerization kinetics showed perfluoroiodide consumption exceeding vinyl, influenced by irradiation intensity.
• Excess vinyl stoichiometry favored ideal alternating propagation and chain transfer (APT) mechanism.

Conclusions:

• Radical-mediated iodo-ene reactions are viable for creating novel polymers.
• High iodine content in these polymers leads to exceptional radiopacity.
• Polymerization mechanisms are sensitive to monomer stoichiometry and reaction conditions.