Enhancing the pre-polymerization coordination of 1-vinylimidazole in bulk solution with ionic liquid additions
Recent experimental investigations have found that the photopolymerization of 1-vinylimidazole (VIm) can be significantly accelerated with the addition of lithium bis(trifluoromethylsulfonyl)-imide (LiTf2N). However, a clear explanation for this phenomenon is lacking, and the underlying molecular level interactions in such a system are unknown. The two components, VIm and LiTf2N, are soluble over a wide range of concentrations at ambient temperature, and if the fundamental behavior of this mixture can be clearly quantified, there are significant opportunities for tuning the polymerization dynamics, polymer structure, and properties. In this work, molecular dynamics simulations are used to model the underlying pre-polymerization structure of VIm/LiTf2N mixtures at several different concentrations. It is found that the Li+ enhances the site-site interactions of key sites involved in the polymerization, and this is suggested to play a major role in the experimentally-observed enhancement of the polymerization behavior.