Improved Photopolymerization Kinetics of Acrylate and Amide Monomers in the Presence of Bulky Organic Salts

As radical reactions are commonly used in the manufacture of polymers and polymer products, interest has increased in new methods of radical polymerization.  Among these techniques is the process of photopolymerization in which the reaction proceeds through the production of radicals from a photoinitiator.  Previously, ionic liquids (ILs) have been found to increase the polymerization rate of multiple vinyl monomers including styrene and methacrylates.  In our study, coordinated ionic liquids were synthesized containing the anion bis(trifluoromethylsulfonyl)imide (Tf₂N) and Li⁺ cations coordinated to the polar vinyl monomers methyl methacrylate, hydroxyethyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, and acrylamide.  The resulting substances were photopolymerized and the monomer conversion measured using real-time Fourier transform infrared spectroscopy (FTIR).  In addition, salt extraction tests were performed on the resulting polymers and the material properties were examined using differential scanning calorimetry (DSC).