Michelle Jia Qi Lua, Hong Tho Le, Atsushi Goto
Polymerizable deep eutectic monomers (DEMs) were obtained using halogen bonding (XB). An electron-donating solid vinyl monomer (N-vinyl-ε-caprolactam (NVCL)) and electron-accepting solid halogenated additives were mixed to form monomer-additive complexes via XB, and the resultant complexes form deep eutectic liquids at room temperature, which are the first DEMs of vinyl monomers using XB. The obtained DEMs served both as monomers and reaction media, eliminating volatile organic compounds in the polymerization process. The free radical photo-polymerization of the DEMs was conducted under UV light (365 nm). Interestingly, the DEMs self-initiated the polymerization under UV light irradiation without the addition of a radical initiator, yielding polymers with number-average molecular weight (M n ) values of 3900-52 000 with 55-100% monomer conversions for relatively short polymerization times of 0.5-1 h. Notably, the polymer obtained in the DEM system exhibited enhanced emission, which could be due to the role of XB in restricting the intramolecular motions of the emitting monomer units in the polymer. The present work expanded the scope of DEMs beyond hydrogen bonding that is currently predominantly used for forming DEMs and highlighted the potential applications in creating novel emissive polymeric materials.