N-Aryl glycines as versatile initiators for various polymerizations†
The design and development of versatile initiators for various types of polymerization reactions, i.e. thermal-/photo-crosslinked/controlled polymerizations, is highly interesting to fabricate high-performance polymer materials. Herein, we synthesized two N-aryl glycine-based initiators, N-(1-naphthyl)glycine (NNG) and N-(1-pyrenyl)glycine (NPYG), and investigated their ability to trigger thermal- or light-induced polymerizations. Relevant photochemical mechanisms to generate reactive species were studied by steady state photolysis, fluorescence, and electron paramagnetic resonance spin-trapping techniques. The synthesized N-aryl glycine-based initiators can act as monocomponent photoinitiators or be incorporated into multicomponent photoinitiating systems for free radical or cationic crosslinked photopolymerization under diverse blue LEDs. Moreover, NPYG was also capable of initiating reversible addition–fragmentation chain transfer polymerization under either thermal- or light-induced reaction.