Enhanced photopolymerization rate & conversion of 1-vinylimidazole in the presence of lithium bistriflimide

• LiTf2N is highly soluble in Vim, producing a coordinated ionic liquid monomer.
• Photopolymerization rate & conversion of Vim are greatly improved with LiTf2N.
• LiTf2N can be recovered from poly(vinylimidazole) in certain aprotic solvents.
• Coordinated ionic liquid monomers eliminate the need for synthetic reactions.

The high solubility of lithium bistriflimide (LiTf2N) in 1-vinylimidazole can be utilized to significantly improve overall monomer conversion and photopolymerization rate. We observed that LiTf2N was miscible with 1-vinylimidazole in stoichiometric equivalence corresponding to a final mixture that is >75% by mass LiTf2N. The rate and conversion of vinyl groups was dynamically monitored using ATR-FTIR. In comparison with the 1-vinylimidazole control, all samples containing LiTf2N exhibited increased monomer conversion and all except the 1:1 sample displayed a more rapid initial reaction rate. The specific effects of the rate and conversion vary with the molar ratio of 1-vinylimidazole to LiTf2N and may be a consequence of coordination complexes between 1-vinylimidazole and the Li+ cation. These results may warrant further investigation into the utility of coordinated, polymerizable ionic liquids that are readily formed from polar organic monomers and LiTf2N.

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