Synthesis and photoinitiated polymerization of new ionic liquid methacrylates

Abstract

Synthesis of new ionic liquid methacrylates and dimethacrylates is described comprising ammonium structures and various anions (bis(trifluoromethylsulfonyl)imide (NTf2), tris(pentafluoroethyl)trifluorophosphate (FAP), triflate (TFl), and trifluoroacetate (TFAc)). The structure of the anion has a stronger effect on both melting behavior and photopolymerization kinetics compared to the cation pattern. Photo‐differential scanning calorimetry investigation shows significant differences in the polymerization rate and final conversion depending on both the polymerization technique (bulk or solution polymerization using an ionic liquid as solvent) and the ionic liquid monomer under consideration. The results show that NTf2 or FAP should be preferred as anion over TFl and TFAc in the crosslinking photoinitiated polymerization because NTf2 and FAP result in both faster polymerization and higher final conversion. Interestingly, the presence of an ionic liquid methacrylate comprising the same anion as the ionic liquid dimethacrylate during the photoinitiated polymerization of the ionic liquid dimethacrylates results in an increase in final conversion that may be caused by lower crosslink density of the network formed, and therefore, higher mobility during the crosslinking process.